Purpose

Aristotle to Darwin

This first section introduces the notion of teleology as it is applied in daily life. It then examines the early history of teleological study, essentially as it appears in the works of Aristotle, then up to the time of Darwin.

Teleology everywhere

When we look closely at nature it becomes evident that almost everything has a function or purpose. The simplest living organism is a masterpiece of design that is more exquisitely crafted towards functional ends than any human artifact. Philosopher Aristotle famously declared that ‘Nature does nothing in vain‘ . . . and how could we possibly disagree?

Purpose, as functional design in nature, is easy to observe and readily understood. We all know why animals have eyes and ears and fish have fins. In daily life we assume without question that birds have wings to fly, spiders build webs to catch flies, and plants have colored flowers, scents, and nectar to attract insects and birds. Almost every part and process of our own bodies has a clear purpose. In fact, we feel triumphant when we find something in the body that doesn’t have a purpose . . . ahah . . . the appendix . . . and mens’ nipples!

It is only when we delve into the source of all this intricate and fine-tuned functional complexity that suspicion about purpose in biological systems begins to surface.

From the dawn of the Scientific Revolution up to the present day the idea of purpose in nature has been under challenge. So what is the problem – why does science currently take such a dim view of nature’s patent purpose?

It all seems to stem from two related questions. First, ‘Who, or what, is the designer that inserted all this goal-directed design into living things . . . and what is the designing mechanism‘? Associated with this question about nature’s designer is a more complex problem that still baffles scientists and philosophers: ‘How can something that lacks intelligence and consciousness, like a tree or a worm, possibly be said to have purposes (or to demonstrate design)?‘

These two questions boil down to a single metaphysical question (a question about the nature of reality). For the scientist this is a question about our scientific ontology (what actually exists). Is purpose in nature real or only apparent: is it part of the fabric of the world or something that our minds impose on the world?

This first section examines Aristotle’s contribution to the debate. The second section considers the subsequent impact of Darwin’s theory of natural selection.

For summary purposes, in this and the next section the major theories about teleology – where it comes from (or not) – are stated as general principles; there are eight in all.

Order, agency, & the pre-scientific mind

The problem of purpose and design in nature relates to a broader scientific endeavor, that of accounting for the order we see in the world.^[4]

There is no self-evident reason why there should be order in the objects and events around us rather than chaos. If everything around us is a product of accident and chance, as we might expect, then why isn’t it all random and disordered? But then, if the world were chaotic it would be unknowable. When we examine nature closely it is not chaotic at all: instead, we have objects as miraculously ordered, integrated, and complex as trees, birds, and human beings. So where does this order come from and why should it be there at all?

Our hunter-gatherer ancestors of pre-history were mostly animists, believing the world to be inhabited by spirits of various kinds – in rivers and springs, trees, forests, and mountains; these spirits and gods made thunder when they were angry, and demanded propitiating sacrifices. Later civilizations assumed that the Gods sent rain to water crops, plagues to punish, and so forth. In the course of human history these spirits seem to have gradually withdrawn from the world, moving first from the lowlands to maintain tops (the Greek gods), then into the sky, and finally departing the confines of space and time altogether. An uncomfortable question now arises. What if there are no spirits and gods . . . who, or what, is then in control of everything?

The concern with order and disorder was a central problem in antiquity. Order and Chaos in the belief system of the ancient Egyptians of the Old Kingdom (c. 2375 BCE) were represented as a symbolic ritual battle between the opposing physical and social forces of Ma’at (order, harmony, truth, balance, and justice) and Isfet (disorder, confusion, lawlessness, and evil). Greek mythology described chaos as a formless and empty void out of which the gods forged the orderly and familiar material world of daily experience.

But it is not just living things that exhibit order and pattern: matter is organized into the different elements and chemicals as neatly presented to every chemistry student in the Periodic Table. Rocks form layers in the earth’s mantle. Stars follow regular and predictable motions in the heavens, the Sun rises each day, and the seasons come and go inexorably, again and again. That there is structure and order is undeniable, but how do we account for it – how did it come to be?

Throughout history, we have found a simple answer to the question of order, design, and purpose in nature and the world. An object like a spear is designed to fulfill a specific purpose, to kill animals – but a spear requires a spear-maker, a designer. By analogy, the order we see in nature is the work of a master designer who is much more powerful and skillful than any human being, in fact, it is a designer with super-human and supernatural powers. That designer must be God(s).

Sources of order & purpose 1 – Theism – The order, design, and purpose we see in the world around us was imposed by its Maker – God(s)

But by what means did God(s) impose this order and – even more worrying – what if there were no gods, what then?

In the West, ancient Pre-Socratic thinkers (c. 624-469 BCE), the first recorded proto-scientific naturalistic (non-supernatural) philosophers, looked for answers in nature itself. Order must have emerged in some way from the world’s fundamental elements: Earth, Air, Fire, and Water. These four fundamental ingredients of the universe were accepted by Plato. Aristotle added a fifth, the aether, a substance that held the stars in their circular motion.

The presocratic philosopher Heraclitus had referred to the rational order of the universe as the ‘logos’ while philosopher and mathematician Pythagoras (570-495 BCE) used the word ‘Kosmos’ (Greek κόσμος) and, like other ancient Greek philosophers, he wondered how this orderly structure had arisen.

Also, from the presocratic philosophers came the idea of nous, which can be interpreted as a ‘mind’ factor imposing the orderliness that gives cohesive unity – an identity that is distinguishable and definable. This was different from the later Greek soul as ‘that which gives life and animates’. Roman commentator Cicero pointed out in The Nature of the Gods that ‘the first human thinker to claim that the orderly disposition of the universe as designed and perfected by the rational power of an infinite mind’ was Anaxagoras. This nous was not a Creator producing something from nothing, ex nihilo, but more a shaper, fashioner, artificer, or architect fashioning the primal chaos. This was a planning or organizing principle that was present in all things.

Today we pass quickly over the order of the universe as the inevitable consequence of incidental scientific laws or physical constants. We don’t pursue the question of why these laws and constants exist, or how they came to be the way they are. We accept that order is ‘just there’, without purpose, intention, design, ends, or goods.

Both Plato and Aristotle believed that Anaxagoras’s cosmology was incomplete. Their universe included not just order, but purpose – they claimed that the world was teleological – not just ordered, but ordered to achieve ends.

It was Socrates (470– 399 BCE) who, according to his student Xenophon’s Memorabilia, first formalized an argument that used cosmic structure as evidence for a grand designer or God, this being the oldest recorded articulation of the famous proof for the existence of God, the Argument from Design or, as we know it today, Intelligent Design.

Philosopher Plato (c. 428– 348 BCE) was a deist. He refused to believe that something as complex as a human being could have arisen by blind chance. How could the objects of the universe, especially living organisms, spontaneously self-assemble – there just had to be some organizing principle – and Plato called this principle the Demiurge which he construed as a transcendental supernatural force like a God.^[30]

The Demiurge wanted everything to be good . . . so far as that was possible, and so he took over all that was . . . in discordant and disorderly motion – and brought it from a state of disorder into one of order, because he believed that order was in every way better than disorder

 

Timaeus 30a^[38]

Like prehistoric hunter-gatherer animists, who believed that spirits inhabited everything, the famous ancient Greek physician Hippocrates (c. 460-370 BCE) – of the doctors’ Hippocratic oath – believed in a vital force, inner spirit, or mystical pneuma (breath) that existed in our bodies over and above the physical matter. This was our source of energy and purposive drive – it was what distinguished a living body from a corpse, and living matter from inanimate matter.

Vitalism (both ancient and modern) proposes some kind of intelligence or mind-like substance influencing or inhabiting minds and the world. This supernatural force has been given many names including anima, pneuma, élan vitale, entelechy, panpsychism, nous (attributed to Anaxagoras (c. 500-428)), soul, and so on – but always as a non-physical supernatural entity inhabiting body, mind, or object – like a soul or spirit, and often assumed capable of existing independently, departing the body at death to persist in a separate mystical realm.

Sources of order and purpose 2 – Vitalism – The purposive energy of living organisms exists as an inner (supernatural) force that is independent of physical matter

Vitalism is now discredited – partly because of the implausibility of such forces, but mostly because they simply cannot be detected and studied.

Aristotle’s telos

Aristotle, like his predecessors, wondered how the order in the world had arisen and he noticed how structure in nature was always reaching for goals. Humans of course were always after something – food, drink, power, the Good Life, happiness, virtue, excellence, sex, and so on. But Aristotle was convinced that it wasn’t just humans that were purposive, it was everything in nature.

Following in the steps of his predecessors Aristotle continued the investigation of goals or ends as telos (Greek τέλος, telos , τελε-, end or purpose, and -λογία, logia) as a branch of learning. This tradition continues today as ‘teleology’ a word derived from the Latin form teleologia coined in 1728 by German philosopher Christian Wolff.^[19]

In true scientific fashion Aristotle began by reviewing the work of his predecessors. He notes that Empedocles (495-430 BCE) thought that the order we see in nature is simply a matter of luck or chance, arising randomly and therefore for no particular reason.

Sources of order and purpose 3 – Chance – purpose in nature arises in a random way by chance or luck

This Aristotle denied. The biological begetting of like from like, of functional complexity, generation after generation, was clearly not a matter of chance.

. . . all natural things come to be as they do either always or usually, whereas no result of luck or chance comes to be either always or usually . . . if then, these seem either to be coincidental results or to be for something, and they cannot be coincidental or chance results, then they are for something

 

Phys ii,198b34-199a5

By contrast the atomists like Democritus (c. 460–370 BCE) were materialists. They postulated a world made up of tiny indivisible atoms united to form the structured world we see around us, all as a consequence of inexorable deterministic natural laws. They, like many scientists today, saw no need to postulate unnecessary objects like purpose or final cause. Atomists, like the scientists of the Scientific Revolution, were content with a metaphysics of the world as matter in motion.

Sources of order and purpose 4 – Necessity – purpose in nature is nothing more than the playing out of material and efficient causal determinacy

So how do purpose and design differ from mere causation?

Aristotle acknowledged material deterministic causation but insisted that if this were so there would be at least as many useless aspects to nature as useful: telos was still needed to provide a complete scientific explanation (what he called a demonstration). Natural teleology was a special kind of causation in which determinate changes were ‘for the better‘ or ‘for the best‘ – independently of human minds.

Aristotle, having examined all the prevailing theories of purpose and order, reached a new and different conclusion.

Intrinsic & extrinsic teleology

God was an extrinsic or external source of purpose and order.

Aristotle believed in God, but as an unknowable eternal and uncreated Unmoved Mover of the universe, perhaps similar to a physical force existing beyond space and time and therefore without human-like characteristics, and certainly without human-like desires or wishes. To think that such a being would be concerned with human affairs was human arrogance.

So, Aristotle looked for the source of order, not in some transcendental spiritual realm as Plato had done, but in the physical and material world of here and now. He disagreed with Plato by claiming that the source of the order we see in any organism is derived from within (intrinsically or imminently). Order, he proposed, derives from an organism’s ‘nature’ which acts like an inner craftsman – it was not imposed from outside by some intelligent agent like Plato’s Demiurge. He made this point by stating that ‘If the art of shipbuilding is in the wood, then we would have ships by nature’ (Phys. ii.8) the point being that the telos of a ship is imposed by humans from outside as an extrinsic teleology while the telos of an organism, its capacity to produce likeness again and again, is derived from within ‘by nature’.

Natural teleology

Aristotle outlines what he means by telos in Book 2 of his Physics (Phys ii.8).^[3] His scientific curiosity acknowledged the deterministic character of natural processes – the linkage of cause and effect, and the high probability of particular outcomes given particular prior conditions. His telos in biology referred to the way that the development of living organisms followed a more or less predetermined path culminating in reproductive maturity as an end point, or goal.

Aristotle had observed that like begets like (humans do not give birth to birds) in a predictable or deterministic way so, in this sense, natural development was ‘for’ something. From this perspective questions about purpose in nature were both legitimate and meaningful, they were not silly subjective questions . . . they had rational and factual answers, so: ‘Why does an acorn exist – what is it for? – answer, ‘to become an oak tree‘. ‘Why does a boy or girl exist?’ – answer, ‘to become a man or woman’.

Some difficulty remains in interpreting, through the haze of translation from the ancient Greek, precisely what Aristotle was trying to say about telos and what his conclusions might mean for today’s biology – but here are some other quotes:

‘Organisms other than man . . . make things neither by art nor after enquiry or deliberation . . . if then it is both by nature and for an end that the swallow makes its nest and the spider its web, and plants grow leaves for the sake of the fruit and send their roots down (not up) for the sake of nourishment, it is plain that this kind of cause is operative in things which come to be and are by nature.’ . . . ‘ And since nature is twofold, the matter and the form, of which the latter is the end, and since all the rest is for the sake of the end, the form must be the cause in the sense of that for the sake of which’.

Physii.8,199

 

Loosely paraphrased in modern language as:

 

‘Non-human living organisms do not have conscious intentions but still demonstrate purposes as part of their intrinsic nature. It is in terms of what structures and processes are ‘for’ that we explain biological systems’

Aristotle’s hylomorphism (physical objects are a combination of matter and form) challenges both ancient and modern science with the obscurity of the notion of ‘form’.^[8] Scientists of the Scientific Revolution, up to the present day, have found the notion of ‘form’ not only obscure but unnecessary: mostly because ‘form’ has no material or empirical presence.

For Aristotle ‘form’ was the essential nature or intrinsic characteristics of an object or entity – that which made it what it was. An acorn is not just the physical material of the seed itself, but also the specific organizational and other immaterial conditions that make it an acorn. ‘Form’, as thus constituted, is our human interpretation of an entity. Acorns are, in a strong sense, human constructs: they clearly exist in physical reality, but the notion of ‘acorn’, with all its human associations, is a human notion. This presents a dilemma. As a distinctly human notion perhaps it should be rejected from science. But without a notion of ‘acorn,’ science has nothing to hold on to or work on – we have no alternative but to accept this ‘form’.

Philosopher Lennox says ‘We may think of the form of an organism as a set of organizing principles, or a set of goal-directed dispositions, to organize its matter in such a way that the organism is capable of performing particular soul functions (in the particular way) distinctive of its kind’^[7] and philosopher Denis Walsh that, for Aristotle, organisms are ‘. . . the very paradigm of purposive, goal-directed systems’. They are what, today, we would likely call ‘biological agents’.

Aristotle’s ‘form’ is an acknowledgment of human presence in all science.  In modern terms ‘form’ might equate to ‘information’ communicating a particular identity or function. Emergent properties as novel properties arising from unique combinations of matter can be seen as analogous to Aristotle’s forms because they are human interpretations of new characteristics emerging from the arrangement and interactions of simpler components. In cognitive science ‘forms’ may be equated to ‘mental representations’ as internal structures or patterns that our minds create to process information about the world.

‘Where a series has a completion, all the preceding steps are for the sake of that’
Phys ii.8,199a 8-15

‘For those things are natural which, by a continuous movement originated from an internal principle, arrive at some completion’

Phys i.8,199b15

‘In natural products the sequence is invariable if there is no impediment . . . It is absurd to suppose that purpose is not present because we do not see an agent deliberating’

Phys ii.8,199b 27-9

In his work De Anima Aristotle draws attention to the close similarity between the telos in nature and human conscious intention: ‘For nature, like thought, always does whatever it does for the sake of something, which something is its end‘.

Ends or limits (as resting places or completions but not necessarily total finality) provide points of stability around which to structure our thoughts. Ends are not confined to the goals of human intention but in living organisms, they are an underlying requirement for meaningful and comprehensive explanation: the explanations of these ‘ends’ are what makes the biological world intelligible. Further, they are ends that do not necessarily imply conscious intention.

From what has been discussed so far it is clear that Aristotle had denied that purpose can only be understood in relation to intelligent deliberation, whether that of humans, or divinities and the supernatural. He had also ruled out the possibility of luck or chance as a source of purpose, and he had noted that the deterministic necessity of natural law does not provide a satisfactory explanation of the purpose we see in living organisms.

We get a better insight into telos by looking at the four major ways Aristotle believed that we provide explanations of why things should ‘be‘. These are known as his four causes.

Aristotle’s four causes – the four major kinds of explanation

Aristotle tried to answer fundamental questions about the world by starting from the simplest possible first principles since this, he believed, was the path to reliable knowledge (epistêmê). So, for example, he asked How can we account for change (kinesis) in the world: why does anything happen at all? and ‘Why does this object exist, what is its reason for being?‘ He was deeply aware of the need to satisfy human curiosity. ‘Knowledge is the object of our inquiry, and men do not think they know a thing till they have grasped the ‘why’ of it (which is to grasp its primary cause).'(Phys. ii.5) In this he was following his mentor Plato, who had stated ‘ . . . philosophy begins in wonder’. (Theaetetus 155c-d, tr. Jowett).

Aristotle wanted to provide compelling scientific or naturalistic explanations (his ‘demonstrations’) for phenomena in the world, and he proposed a toolbox of four ’causes’ (aitia) each being ‘something without which the thing would not be‘. This was a key part of his metaphysics – his ‘science of being’.

Aristotle’s account of change included his four causes combined with the notions of potentiality and actuality.

These thinking tools, Aristotle suggested, provided the major explanatory resources needed to investigate the natural world. They were scientific first principles. They were not causes, as we understand them, but ‘be-causes’ or modes of explanation that provided reasons, or grounds, for existence and change.

1. What is it made of? (material cause) – ‘that from which’ – explanations given in terms of substance, matter, or parts

2. What is it? (formal cause) – ‘that which makes it what it is’^[6] – Greek eidos. This has several slightly different senses: firstly, something’s shape, arrangement, structure, or appearance; secondly, its essential character or kind communicated by a definition; thirdly, biologically an inner species-specific capacity for functional organization passed from generation to generation (like today’s developmental information contained in the genetic code)^[32]

3. What produced it? (efficient cause) – ‘the maker or mover’ – a mechanism of change equivalent to today’s ’cause’ as ‘what happened before’ (the initial trigger of change, a mechanical interaction like one billiard ball hitting another, or parents producing a child)

4. What is it for? (final cause) – ‘that for the sake of which’ – Greek telos. The purpose (fulfillment, goal, destiny, outcome) for something, the end to which it is directed.

Put simply, his ’causes’ answer the questions: what is it made of, what is its defining structure or characteristic(s), what is its method of production (how did it arise), and what is it for, what is its end? Not every answer required all four be-causes.

As an example we can use all four ’causes’ to explain a table as follows. The carpenter (efficient cause) selects a particular wood (material cause) to fashion into a particular kind of object, a table (formal cause) so that he has somewhere to sit and eat (final cause). Aristotle believed that material and efficient causes alone do not provide a complete explanation: it is the formal cause that gives an object structure and meaning and in the case of an organism the formal cause is its defining structure or organization.

The four causes also divide neatly into two pairs. The material and efficient causes capture an analytic bottom-up physical and material perspective on the world and change. Formal and final causes offer a synthetic, integrating, unifying, agential and purposeful perspective. The Scientific Revolution (depicting a mechanistic world of matter in motion) abandoned formal and final cause (as beyond experiment and observation), uniting non-human life with the material and efficient. By restricting purpose and agency to humans, and without the benefit of the theory of evolution, it distanced humans from their continuity with the community of life.

A modern example of the application of Aristotle’s four causes might be the way that biologists have argued about the best way to define the gene: should it be structural (material cause), positional (formal), historical (efficient), or functional (final)?

A strength of Aristotle’s four ‘becauses’ is that they are both static and dynamic . . . they include both past and present. They incorporate both structure and function.  By considering potentiality, actuality, and the temporal sequence of efficient cause they allow for history, development, purpose, and agency. They explain the way things are now, but also account for change by explaining how they came to be. And their meaning allows some flexibility of interpretation (Aristotle pointed out that the Greek word aition as ’cause’ had various senses).

Formal cause (see short discussion at ^[6]) is associated with the idea of ‘essence’, regarded by many today as an unnecessary or mistaken assumption about existence and referred to as ‘essentialism’: the idea that something may be defined using necessary and sufficient conditions. Aristotle distinguished between the essential defining or key characteristics that determine what an object is, as opposed to accidental properties that are peripheral.

For Plato the essence of an object (what particular things have in common – say the ‘catness’ of cats) was its Form as an abstract and eternal transcendental idea outside space and time. Aristotle thought that these ideas (also called universals) were not transcendental but in some way associated with the physical objects themselves. It is easy to deny both claims; but remember, without these abstract universals it would be impossible to do science.

The idea of formal cause may be confronted by considering what it is that makes you you – bearing in mind that, it is sometimes said, every molecule in the human body is replaced in seven years? What is the material difference between a living body and its corpse?

Aristotle’s biographer Armand Leroi, an evolutionary biologist working at Imperial College, London, presents Aristotle’s causes in a schema that represents today’s biology in a very general way by equating material cause to biochemistry and physiology, formal cause to genetics, efficient cause to developmental biology and neurophysiology, and final cause to evolutionary biology and the study of function and adaptation.^[8] Leroi concludes that Aristotle totally transformed the transcendental world of Plato ‘ . . . by the time he was done, matter, form, purpose and change were no longer the playthings of speculative philosophy but a research program’.

Aristotle also noted that teleology has two parts, the ‘of which’, aim, or function (say, of an eye ‘to see‘, of a heart ‘to pump blood‘) and the ‘for which’ or beneficiary, the organism deriving the benefit. Today we would, in a general sense, regard the genetic code as the ‘inner nature’ or, to use Aristotle’s analogy, the ‘inner craftsman’ that provides the critical information whereby ‘like begets like’. We recognize ‘like’ organisms by their intergenerational similarity as the formal cause that gives them structure and meaning.

Sources of order and purpose 5 – Natural teleology – Telos – ‘that for the sake of which’. An inner nature, capacity, or principle of change that exists in living organisms as a function or purpose: the realization of pre-existing inner potential. Natural teleology has both a function (aim) and a beneficiary

Natural teleology can be expressed in a more formal philosophical way as: ‘. . . the realization of pre-existing internal potential (as formal-efficient and material-efficient causation) through stages framed by conditional necessity’.^[22]

The realization of the form is the end state to which the efficient cause is intrinsically (non-consciously) directed – a condition of completion in respect to capacity or potential. Thus, all change is the realization – the actualization – of potential. The idea of telos was Aristotle’s contribution to this philosophical discussion. It was telos that provided a focus for causal explanation: without it the phenomena under investigation would be simply dissociated facts of the universe.^[29]

Backward causation

It is a characteristic of teleological explanations that they infer something about the future (ends, goals) relative to what is being explained, as though the future is causing something to happen in the present.^[60] This implication of future causation is often treated as a definitive failure of teleology.

So, what is going on here? When we say ‘spiders build webs to catch flies’ we have an eye on the future as well as the past. Are we implying that the future causes spiders to catch flies, or that spiders can anticipate the future?

Future causation has no place in science: the world is the way it is today because of events that occurred in the past, or are happening in the present, not because of what will happen in the future. But in biological systems the future is always there as a ghostly presence.

We humans, as part of our conscious reasoning, use hindsight and foresight to anticipate, but we cannot assume the same for spiders.

Students study to pass examinations. So, are future examinations the actual cause of the studying?

On closer inspection, mental anticipation (the imaginative reconstruction, in the present, of what might happen in the future) is the real cause – a subtle but critical difference. There is no future cause.

Our human concept of purpose is based on our capacity for both backward and forward modes of thinking.  We can anticipate the catching of flies in a web and its implications while a spider, we assume, cannot. But just because only we humans can anticipate (use foresight and hindsight to understand consequences, reasons and purposes) does not mean that only we humans have consequences, reasons and purposes. A spider’s web can be ‘for’ catching flies, even though the spider does not know this. Because humans can anticipate – because they are reason-representers (philosopher Dan Dennett) – does not mean that they are the only creatures with reasons and purposes. What is uniquely human is the ‘anticipation’, not the reasons and purposes themselves. We mistakenly conflate absence of subjective anticipation in many organisms with absence of purpose, treating them only ‘as if’ they had reasons and purpose.

If we infer what something is for from what it does – what its role is in the overall life of the organism – then completed processes and parts unsurprisingly become the starting point of functional scientific explanations and why they have explanatory priority. There is a difference between our forward-looking explanatory order (the order we use for explanations, in which ends come first) and the causal order that gave rise to the biological traits being discussed.^[5]

In sum: the future does not provide the necessitating conditions for its own realization: it does not exert a mysterious causal pull. There is no backward causation in biological systems, and that includes human minds. Final causes are direction-givers and ends, the limits of development necessitated by formal-efficient and material-efficient causation. They are part of the conclusion that is being demonstrated.^[34] Though they are given first in any explanation, they are the last in causal sequence . . . first in order of conception, last in realization.

Identifying final causes (reasons, purposes, functions) aids the search for material, formal, and efficient causes that are parts of a complete causal explanation.

The giraffe’s long neck – an adaptation for reaching – was not anticipated or planned by a mind, nor was it mysteriously caused from the future – but there were reasons for its emergence, and its purpose is abundantly clear.

A pile of bricks and construction materials makes no sense unless we have a concept of a house. Ends are necessarily first in explanation but last in causal sequence.

Commentary

In confronting the problem of order in nature Aristotle had noted the regular character of causal necessity. This was as true of the inanimate world as it was of living organisms. Today we attribute this necessity to physical constants, the ‘laws’ of nature. For Aristotle, who had no knowledge of scientific laws, objects in nature were, in a sense, moving to their appointed places . . . apples falling to the ground, and smoke rising into the sky. But Aristotle knew, as we do today, that this was not the universe striving to reach goals in a human-like way, it was instead the inbuilt nature of things. Scientists today (like Aristotle in his day) study causal effects or ‘ends’ without necessarily assuming the agency of mind or intelligence.

But Aristotle also realized that the telos of animate nature, of living creatures, had additional special qualities. He was aware that the orderly design of crystals, the predictable behaviour of the solar system, the way water assumes the shape of its container, and the way that pebbles are graded by size on the seashore, are a different kind of order from the order we see in biology. Living organisms had something in addition to the physical necessities that are part of the world of crystals, mountains and other inanimate objects. Living organisms had complex organization, they persisted by reproducing their kind, and they could be beneficiaries of purposes that promoted their survival and reproduction – even though these were not conscious needs and interests like those we associate with humans.

So, in the animate world we see adaptations as ends (effects) that have beneficiaries, and in so doing telos becomes natural teleology. Function, design, and purpose arise in nature in the absence of an intelligent agent. Organisms can be beneficiaries even though they are unaware of their benefits.

Science proceeds on the assumption of causal necessity, of the connection between cause and effect (or end). Without ends or telos, explanation is empty, it is simply not possible. And where causal necessities (reasons as functional adaptations) entail beneficiaries, where they are ‘for the better’ then we are entitled to speak of processes being ‘for’ purposes.

Aristotle insisted that telos had nothing to do with the divine and supernatural. The inner capacity or ‘nature’ of organisms is not some mysterious inner supernatural force, but neither is it the mapping of human intention onto nature as a metaphor for human deliberation. An organisms ‘nature’ ensures that like begets like (unless prevented from doing so), it is why human embryos become human beings, acorns become oaks, and, as he expressed it himself, ‘stars do not have feet‘. It is correct that we only appreciate nature’s inherent purposiveness because our human minds ‘see ahead’, but this does not mean that the purposiveness itself is in our minds.

When Aristotle remarks ‘If, therefore, purpose is present in art, it is present also in nature. The best illustration is a doctor doctoring himself: nature is like that‘ Aristotle’s point is that the purposiveness we see in biology arises not from our minds but from a kind of ‘inner administrator’. Today we would say it comes from the information/instructions carried in our DNA. However, that is where the comparison ends. Clearly nature does not have conscious intentions.

The ancient world came very close to a theory of organic evolution. Here is a quote from the Hardie and Gaye translation^[33] of part of Aristotle’s Physics Book 2:

Wherever then all the parts came about just what they would have been if they had come to be for an end, such things survived being organised spontaneously in a fitting way; whereas those which grew otherwise perished and continue to perish, as Empedocles says his ‘man-faced ox-progeny’ did.
Phys ii.8,198b29

And my paraphrase of Hardie and Gaye (I hope you agree):

How do biological structures arise as though they are designed for a purpose? They persist because they are organised by nature in a purposeful way while those that are not organised in a purposeful way, like Empedocles’s man-faced oxen, will die out.

Sicilian pre-Socratic philosopher Empedocles (c. 490-430 BCE) thought that the various body parts we see in the animal kingdom had once all been mixed up but that ‘. . . the human head, by combining with the human body, brings about the preservation of the whole, but by combining with the ox’s body fails to cohere with it and perishes. For those which did not combine on proper principles perished. And things still happen the same way nowadays …’.

Interpretation of this passage about Empedocles is contentious but is discussed by author Armand Leroi who points out that the notion of selection in nature was probably ‘commonplace’ in classical times. Lucretius (99-55 BCE) in De Rerum Natura describes the way ‘The fertile young earth naturally sprouted with life forms, and the organisms thus generated were innumerable random formations. Of these, most perished, but a minority proved capable of surviving — thanks to strength, cunning, or utility to man — and of reproducing their kind‘^[7]. The sixth century Roman commentator Simplicius remarks that many natural philosophers of his day held this view (Physics, 371.33-372.11), so crude versions of natural selection were circulating at least 2000 years before Darwin.

The mechanism whereby purposiveness is acquired will be discussed in more detail in the next article … Darwin and after . . .

The links between teleology, human nature, sustainability and plants will become apparent later.

Citations

[1] https://www.youtube.com/watch?v=3L7uNyQL0H0
[2] Several modern philosophers (see Meyer (1992), Johnson (2005), & Leunissen (2010)) argue that Aristotle’s attention and claims were not so much about deterministic causation (necessity), or the compatibility or reduction of one kind of cause to another, instead his claims stand or fall on the distinction between intrinsic and incidental causation. That is, he opposes the view that the development of animals and plants is in any way accidental: if their development is not coincidental then it this sense it must be for something, it is goal-directed, and natural teleology stands. This might seem like obfuscation and needs some explanation.
Teleology is diminished by comparing it to material necessity and chance. Teleological explanations do not explain away material necessity (Balme 1987c), reduce it to conditional necessity (Johnson 2005), or negatively constrain the realization of function (Lennox 2001a).
Philosopher Mariska Leunissen recognises two kinds of Aristotelian teleology: primary teleology, driven by form, and the realization of pre-existing potential for form ‘for the sake of’ through stages limited by conditional necessity and leading to ends that are needed to perform the vital functions of the organism; a weaker secondary teleology, driven by matter, as the use of materials that are not a part of the organisms vital functioning and not dependent on conditional necessity: they are secondarily co-opted by the formal nature of the organism. This secondary teleology is ‘for the better’ or to help the organism to ‘live well’ rather than being critical – like our hair – and depending on material availability rather than a pre-existing potential for form. But we need to know if the end point is the realization of existing potential for form (driven by form) or the use of available materials by material necessity (driven by matter). Both are goal-directed but the former are formal-efficient in primary teleology and material-efficient in secondary teleology.
[3] Philosophers have differed in their interpretation of Aristotle’s work, the debate too complex to follow up here (see Johnson 2005, Leunissen 2010). I have tried to remain faithful to the original text
[4] Science is, in its broadest definition, the study of order. Orderly structures and processes preceded human minds by more than five billion years. The arrival of order in the universe marked the introduction of mind-independent meaning which arises in matter, not the mind. There are reasons for order in the universe but only minds have reasons. Order begins with meaningful cause and effect where effects have causes as reasons.
For some philosophers (e.g. Dan Dennett) matter in orderly motion is insufficient for meaning. For them meaning only arises when there are agents, like organisms, that can extract and use information from the environment and therefore demonstrate purpose
[5] The materialist explains beneficial outcomes as the results of materially necessitated processes. But for Aristotle beneficial outcomes cannot be a matter of arbitrary necessity as we would expect in a world comprised simply of material and efficient causes. The material necessity operating in organisms can only be adequately accounted for by including formal and final cause.
[6] Aristotle maintained that every physical object is a mixture of matter (what it is made of) and form (its essential or defining properties), a doctrine known as hylomorphism (Gk hulê, hyle – matter, what an object is made of; eidos or morphê – form), a claim that he developed in the Physics. Form, for Aristotle, is what unifies a piece of matter into a single object. Hylomorphism is sometimes referred to as Aristotle’s doctrine of the ‘soul’, not in a theological sense, but as the unity of form and function that constitutes the organizing principle of life . . . the cause of a body’s being alive (De An 415b 8). This is what gives life its vitality, or, what today we would refer to as its agency. The specific combination of body and soul found in each biological kind characterizes what it means to be alive for that sort of living thing.
[7] Lennox, J. 2001. Material and Formal Natures in Aristotle’s de Partibus Animalium. In Aristotle’s Philosophy of Biology (pp. 182-204) Cambridge University Press: Cambridge University.
[8] Aristotle’s mentor, Plato, developed a theory of Forms (sometimes called ‘universals’) as a realm of abstract properties or ideas. Plato’s Forms were the essential characteristics or properties that determined, or defined, what it was to be, say, a human, tree, cat, dog, love, beauty, or the colour green. For Plato, Forms were extra-mental and real phenomena, the purest representation of an object. His Forms had an enduring reality in a universal, eternal, and timeless world of being, while the material objects that these properties so often described were part of a world of becoming, variety, and change. A Form was a distinct and singular thing that has multiple representations of itself (the ‘problem of universals’ e.g. the physical variety that exists under the general concept ‘dog’). To support his claim that Forms are real, Plato pointed out that though no one has ever seen a perfect circle, or a perfectly straight line, everyone knows what a circle and a straight line are. Material objects, he believed, were part of the deceiving world of the senses: they have the natures they have because they ‘participate’ (sic) in the Forms.
Plato’s theory of Forms has attracted various criticisms. If Forms are eternal (they do not exist in space or time) – then in what sense can they be regarded as ‘real’. And, even if they are ‘real’, then where do they actually exist? If they aren’t in the physical world, or minds, then where else could they reside? These questions make Plato’s Theory of Forms, at best, difficult to comprehend. Material objects clearly have properties but, expressed crudely, these properties do not float around independently of the objects they describe.
Aristotle accepted Forms as the essential properties of objects, but he insisted that they were intrinsically linked to them, not existing in a separate realm. Forms are the essential qualities (defining properties, concrete particulars) that an object must have if it is to be considered that object.

Forms today
Following the tradition of the Scientific Revolution (initiated mainly by astronomers and mathematicians) and its debunking of biologist Aristotle, biologists today explain their science, like physical scientists, using Aristotle’s material (what it is made of) and efficient (how it arose) causes which ignores the critical distinction between life and non-life. Aristotle’s formal (essential defining features) and final (what is it for, its purpose) modes of explanation are what most effectively define life. These causes are generally ignored – in principle though not in practice – following the presumption of the Scientific Revolution that they are beyond the reach of experiment and observation. Modern biological science chooses to ignore Forms and purpose in biology as an embarrassment of the past – but this does not mean that these ideas have gone away.
Purpose and function in biology are derived from the objective, universal, and ultimate goal-directedness (agency) that is an inherent part of what it is to be a living organism – and it is this factor that makes biological explanation both meaningful and experimentally verifiable. As Aristotle pointed out, biological agency (final cause) is what most obviously distinguishes the living from the inanimate and the dead.
Form, for Aristotle, is what unifies a piece of matter into a single object (sometimes referred to as a ‘kind’): it is what gives identity and individuality to ‘substances’. Aristotle’s meaning of ‘substance’ is different from today’s meaning and, indeed, what he does mean is obscure – is it ‘essence’, ‘universal’, ‘subjects of predication’ or something else? It seems that, at least in part, Aristotle was looking for the ‘essence’ of each of the objects of our experience. Unfortunately, though the words we use to designate these objects have meaning, that meaning frequently does not satisfy our desire for clear and distinct ideas . . . they do not have the necessary and sufficient conditions (classical categories) that satisfy what we might call an object’s ‘essence’.
This philosophical discussion leads down many paths, but for our purposes we simply note that our minds fragment the world into ‘objects’ (concepts, units of experience) that are meaningful within the evolutionary context of our human umweldt – the world as seen and experienced through our uniquely human sensory apparatus and brains. Our understanding of these objects, most notably the objects of scientific investigation, seem to approach what Aristotle calls forms.
As individuated objects of thought these forms (units of mental experience, things) appear subjective and mental – they are certainly not matter as we usually conceive it – and yet they also include the objects of scientific investigation as well as tables and chairs, cars, trees, human beings, and mitochondria, as well as more obscure things like goals, ideas, love, desire, unicorns, and marriage.
Without the capacity to ‘individuate’ our world of experience, we could not exist. The extent to which these individuals (Forms) exist in our minds, or in the world, is a matter of degree that is decided by our science.
Forms are not matter – and yet science is impossible without them. Their abstraction and resistance to experiment and observation has traditionally been regarded as a hindrance to science, a metaphysical encumbrance best ignored. This may be true in a practical sense, but as part of the apparatus we bring to science they must be taken into consideration. Form is an individuating characteristic because it infers that a thing with many parts comprises a single individual, a unity, and not a plurality.
Our uniquely human experience of the world is constrained by our uniquely human sensory apparatus. The objects of our experience are not only the necessary components of our day-to-day existence, they are also the elements we use to understand and explain the world. Whatever their true nature, we cannot do without them. Forms, as our understanding of the objects of our experience, are uniquely human representations (interpretations) of the world. This does not mean that they are mental constructs, and purely subjective: they are the mental evolutionary products of the interaction between biological agency and the world’. They are ‘real’ to the extent that they have resulted in human persistence on the planet.
The Form of a living organism – its essence, or most efficiently defining characteristic – is its purposive or functional character, its biological agency as stated in the biological axiom. A statue may be shaped like an organism, but it is not an organism because it cannot perform the functions characteristic of organisms. In the case of living organisms, the Aristotelian formal and final causes are the same.
The biologically significant point is that the matter and form of organisms are interdependent concepts: form is enmeshed in matter, but one is material and the other immaterial. Such essences or definitions may be accused of being mind-dependent, abstract, abstruse, and unnecessary metaphysical constructs but they also connect to the world that is beyond minds. Insofar as they connect to the external world in a manner that supports the organisms’s survival, then they are objective and real. Biology rests on the key notions of the organism and the species. It is the universalization of the ‘abstract’ species that makes the science of biology possible

References

See next article for references.

Darwin’s contribution

All things bright and beautiful
All creatures great and small
All things wise and wonderful
The Lord God made them all

Each little flow’r that opens
Each little bird that sings
He made their glowing colours
He made their tiny wings

First two verses of a hymn with words by Cecil Alexander (1818-1895)

                                                       Published in 1848, eleven years before Darwin’s On the Origin of Species in 1859

When Christianity followed in the wake of the Greco-Roman empires, purpose in nature was attributed to the purpose of the Christian God at the time of his Creation of the world. This was an extrinsic teleology. It was God who had fine-tuned the wondrous and intricate complexity of everything. The purposive design so pervasive in nature was a compelling demonstration of God’s intelligence.

The Argument from Design, as evidence for the existence of God, was uncontested. Nothing in biological science could explain the infinite functional complexity of eyes, brains, flowers, and leaves that was so immediately obvious to everyone.  This purpose in nature, so clear to all, was God the Creator’s purpose.

From at least the time of the ancient Greeks only a few people had seriously considered the possibility of species changing as they reproduced again and again over many generations. In Darwin’s (1809-1882) day this idea was called transmutation or transformism but its advocates had little evidence and so they were generally regarded as crackpots.^[20] How could organisms possibly change over the years? There was simply no explanation of how this could be done. Scientific principles of inheritance had not been established at this time so there was no known mechanism to bring about such a change, except possibly for the Lamarckian inheritance of acquired characteristics (e.g. that a blacksmith’s son would inevitably have bulging muscles like his dad) a theory that did not square with the facts.

The Darwinian Revolution

Then in 1859 Charles Darwin (1809-1882) published On the Origin of Species . . ., the central argument of the book being his theory of natural selection which contributed to the English language the memorable phrases ‘survival of the fittest‘ (sourced from Herbert Spencer’s 1864 account as acknowledged by Darwin) and ‘struggle for existence‘.

Darwin’s momentous contribution was to provide a mechanism whereby species could gradually change over time. It was a totally different explanation of the biological world than anything before. Natural selection provided a coherent naturalistic (non-supernatural) answer to the question ‘How could the biological diversity of the world we see today have possibly arisen?’ Darwin gave us a compelling explanation of how the entire community of life, humans included, arose by descent with modification from a common ancestor. The evidence for evolution was overwhelming – drawn from geology, paleontology, biogeography, and anatomy, and subsequently supported by molecular biology and all branches of the life sciences.

What made natural selection so special was that it added a further ordering process to the ordering processes we call the ‘laws of physics’. About 3.5 billion years ago discrete and mindless aggregations of organic matter (proto-organisms) acquired the capacity for self-replication, varying slightly as they did so. This resulted in differential reproduction in respect to the surrounding conditions such that those proto-organisms meeting the requirements of their environments tended to persist under replication: those whose heritable variations made them better suited to their environments tended to be the ones that, over many generations, would persist since it was these that remained to survive and reproduce. Natural selection occurred when self-replicating matter developed the capacity for ‘heritable’ variation that was subject to differential reproduction.

From one perspective this was a mechanical and statistical sorting process like the size-grading of pebbles on the beach by the tide. From another perspective it was a process of temporal physical change operating on semi-autonomous replicating matter. It ‘offered’  these individuals ‘self-correction’ in relation to the surroundings such that some individuals could ‘benefit’ by being able to survive and reproduce. It also created competition – with ‘winners’, ‘losers’, and organic evolution.

Darwin described the process of fitting into the environment as ‘adaptation’ and the process of gradual physical change to produce these adaptations as ‘natural selection’.

Thus, over numerous generations, speciation would occur as organisms gradually changed into new species. Materially, natural selection is an interaction between semi-autonomous replicating matter (an organism) and its surroundings (the environment). It is a rudimentary process of auto-modification using environmental feedback or ‘self-correction’ within the organism-environment continuum: it extracts information from the environment via a feedback mechanism.

Mathematically natural selection acts as a recursive sorting algorithm (used in evolutionary computation).

Darwinism coincidentally drew attention to what amounted to an Aristotelian tripartite material distinction: the set of all matter ordered by the laws of physics; the subset of living matter ordered, in addition, by the sorting algorithm of natural selection; and the further subset of living matter that had the capacity for foresight, hindsight, abstract reasoning, and self-awareness.

Sources of order and purpose 5 – Natural selection.

Evolution is, then, a mechanical sorting process whereby organisms better adapted to their environment tend to survive and produce more offspring. It is also a mindless process generating purposive products.

For many scientists and philosophers the attribution of the word ‘purposeful’ and ‘designed’ to the products of mindless and mechanical natural selection is simply unacceptable.

From ladder to tree

Darwin’s theory deeply insulted the sensibilities of his day, undermining many widely and tenaciously held beliefs.

First, there was the conviction that species were immutable. Each was perfect, a unique creation placed on Earth by God. There was no reason why it should change. The idea that new species could gradually emerge over many generations was considered not only absurd but blasphemous.

Second, and even more insulting to the dignity of humans (the pinnacle of God’s Creation) was the implication that humanity had emerged in a decidedly undignified way from ape-like ancestors. For this suggestion Darwin was mercilessly lampooned in the newspapers by cartoonists who depicted him as a monkey.

Third, Darwin’s theory placed in question the imagery of one of Aristotle and Plato’s most widely-accepted ideas about the structure of the natural world, the scala naturae, the Great Chain of Being or ‘Ladder of Life’ as adapted by Christianity. This was a popular understanding of the whole of the Creation on Earth arranged hierarchically from higher to lower like the rungs of a ladder, and surmounted by its crowning glory the human being, eclipsed only by God.

While contemplating the origins of living organisms Darwin had drawn in his notebooks, not a top-to-bottom ladder, but a tree-like structure where humans, for all their magnificence, were not at the top, but at the tip of a branch. The selective interaction between organisms and their environments had branched into many solutions. Darwin had replaced the popular metaphor of the living world as a hierarchical ladder with that of a radiating and diversifying tree.

Fourth, Darwin’s theory was profoundly disturbing because it undermined a universal human belief dating back into prehistory, the conviction that there was a supernatural and intelligent grand design to the living world, the universe, and everything in it. On the Origin of Species . . . had removed the necessity for God as an integral part of our understanding of nature, and this changed human perception of the world forever.

Darwin argued convincingly that the entire community of life had arisen over many generations by means of an intelligible mechanical process of ‘self-correction’ whereby, over many generations, organisms could ‘fit better’ into their environments. He called this process natural selection. It was a mindless natural process that had taken an extremely long time, and it was a process whose steps we might never know in precise detail.

Before Darwin it was the general belief that everything had been created and placed independently in the universe by God as part of his divine plan. Darwin was a unifier who showed how all matter was related – the organic arising from the inorganic, and living organisms, the community of life, united by common ancestry.

This historical and material commonality was reinforced when, in about 1930, the Steady State theory of the universe was replaced by that of the Big Bang, the entire universe postulated as exploding from a point source out of which all else had ‘grown’ or ‘evolved’. Humans were built from stardust. Perhaps unwittingly, by describing the interdependence, interconnectedness, and intergrading of everything organic, Darwin had reinstated Aristotle’s organismic metaphor of the universe. Upgraded in recent times to something resembling a computer with the organic interconnectedness of a brain.

Immanuel Kant had said there could never be of a ‘Newton of a blade of grass’, seemingly rejecting the possibility of a coherent explanation of the organic world, or maybe even the impossibility of a respectable biological science. It is Darwin’s unifying contribution to our historical account of the community of life that earned him the title Newton of Biology.

The end of teleology?

Many scientists and commentators assumed that Darwin’s revelation had purged biology, once and for all, of both God and teleology. Natural selection was a mindless mechanical interaction between organism and environment that could not see into the future. Birds had wings because wings and their precursors in the past had conferred a selective advantage on those creatures that possessed them. Efficient causation was sufficient to account for organic change.

Why should we expect more than this? Darwin gave us a process narrative of how, during evolution, bird wings arise by a natural physical process. What Darwin showed was ‘how a purely causal process – blind variation and environmental filtering (natural selection) – can produce adaptations as biological structures with functions’^[55] Why add the complication that wings arose ‘in order to’ permit flight . . . that wings are ‘ . . . for flying‘.

If Darwin was correct, it was argued, purpose and design in nature are only apparent purpose and design because they emerge in a naturalistic and causally transparent way. Even something as complicated as the human eye could be explained coherently in terms of a series of small evolutionary steps. Teleology, it seemed, was only mechanical Darwinian adaptation, so true teleology could now be removed from mainstream biology, and returned to its rightful owners . . . intentional agents like humans and God.

Even Darwin’s close friend and advocate Thomas Huxley, in a review of On the Origin . . . written for the London Times newspaper on Dec. 26 1859 declared that Darwin had freed the world of ‘. . . the snares of those fascinating but barren virgins, the Final Causes . . .’^[54]

Another of Darwin’s contemporaries, Karl Marx (1818-1883) in a letter to Ferdinand Lassalle in January 1861 wrote:

‘Darwin’s book is very important and serves me as a basis in natural science for the class struggle in history. One has to put up with the crude English method of development, of course. Despite all deficiencies, not only is the death-blow dealt here for the first time to “teleology” in the natural sciences but their rational meaning is empirically explained.’

Marx, like many others up to and including the present day, assumed that teleology had been put to rest when just the reverse had happened. Darwin had explained how the manifest designed wonder of the natural world had arisen out of an ignorant mechanical process. Explaining how purpose arose in nature did not remove it – it did not explain it away. Explaining how spines evolved as adaptations on desert cacti provides a naturalistic explanation but it does not magically erase the purpose they serve. Similarly, recognizing that the intricate design of a leaf does not need either God or the human mind does not place that design in the human head. The design exists in nature. It is not ‘as if’ or ‘as though’ the leaf is designed – it is not ‘designoid’ – and therefore lacking or incomplete in some way. The leaf is designed to a level of sophistication that humans cannot achieve. The requirement that ‘true’ design is design by an intelligent designer (which, in the absence of God must be the human mind as metaphor) is human arrogance.

Natural selection itself is mindless, unintelligent, and without foresight . . . it cannot possibly have purposes and goals. And yet the products of natural selection, organisms, clearly exhibit purpose as adaptation, that is also functional design, even though they lack awareness of both. The products of natural selection are ‘for’ without foresight‘ (my contribution to the popular alliteration that litters this topic). Darwin had not explained teleology and design away: by providing a naturalistic explanation for their presence he had given them scientific legitimacy and made teleology honest. True, he had removed the ‘intelligent’ from ‘intelligent design’ but he had left the ‘function’, ‘purpose’, and ‘design’ intact. The shocking reality, so difficult for people (including scientists) to accept, was that the entire designed and purposive community of life had been ‘created’ by a non-intelligent process.

The difficult intellectual step here – what philosopher Dan Dennett calls a curious ‘inversion of reasoning’ –  is the acknowledgement that reasons and purposes can exist independently of reasoners. Humans do not put reasons, purpose, and design into nature, but they are the only organism that is aware of them. There are reasons why the Earth orbits the Sun, the spider builds a web, the grass is green, and I have a headache – even though the Earth, the spider, the grass, and I, are unaware of these reasons.

The single major objection to teleology is that nature cannot have reasons, ends, or purposes: only humans can have reasons or purposes because only humans are capable of conscious deliberation. A spider’s web cannot manifest purpose or design because spiders do not have human-like intentions.

There is a subtle distinction here. Certainly, we are in error when we associate web-building with spider foresight but, importantly, we are also in error when, as a corollary, we deny the connection between web-building and catching flies. We make the mistake of assuming that only foresight can provide a reason or purpose for web-building. We assume, in error, that because only humans can understand reasons and purposes, then only humans can have (manifest) reasons and purposes.

Reasons were present in the universe long before humans existed. The organic world is saturated with reasons, but only humans can represent these reasons. Philosopher Dan Dennett has expressed this eloquently by pointing out that organisms are ‘competent without comprehension‘ and ‘reasons do not require reason-representers‘ . . . ‘humans are the only reason-representers‘.^[40]

By providing an explanation for teleology Darwin had not explained it away, he had simply grounded it in natural selection, he had naturalized it. He demonstrated how, in living organisms, organic change is purposive because it creates beneficial functional adaptations – and it does so without consciousness, foresight, intelligence, or deliberation.^[51]

Principle 1 – Reasons, functions, and purposes can exist independently of consciousness

So, natural selection is mindless, but it results in organisms that are ‘competent without comprehension’, and ”for’ without foresight’.

Principle 2 – Humans are the only self-conscious reason-representers

But there is also a subtle distinction between reasons and purposes.

Principle 3 – our understanding of ‘purpose’ is strongly associated with the idea of benefit –  expressed in biological terms as (functional) adaptation

Polysemy

Earlier it was pointed out that the central problem under discussion is not about semantics. However, the conceptual complexity of teleology-related words must be acknowledged – the semantic nuances of words like ’cause’, ‘reason’, ‘purpose’, ‘selection’, ‘adaptation’, ‘function’, and ‘design’ and the extent to which some words tend towards being ‘mind’ words and other words tend towards being ‘world’ words. Darwin and his natural selection bequeathed to us a can of scientific, philosophical, and linguistic worms.

The semantic range of the word ‘reason’ is very broad and seemingly associated with that of the word ’cause’. In everyday language the word ‘purpose’ is broadly defined as the reason why something is done or why it exists, and we tend to use it in relation to reasons that are conscious human intentions. The products of evolution are confusing because they demonstrate purposes in the absence of intentions. Language (and our minds) then stumble in the attempt to represent this state of affairs.

As scientists, should we be advocates of purpose in nature or should we try to get rid of it by becoming teleological eliminativists?

From the days of the Scientific Revolution many scientists and philosophers have insisted that the word ‘purpose’ has no constructive role to play in non-human biology, so it should be used restrictively, applying only to human conscious intentions, thus purging nature of purpose. So, let’s examine more closely the possibility that purpose in nature is a creation of the human mind.

Teleological censorship

If teleological language is non-scientific and superfluous, a projection of human thinking onto nature, then wouldn’t it be best to remove it altogether (teleological eliminativism)? Perhaps it can be replaced by the language of functional analysis. We could change statements about ‘what something is for‘ into statements about ‘what something does‘ or ‘how something works‘^[11] and in this way the purposive aspect can be eliminated and forgotten. Isn’t it simpler and more scientifically acceptable to use a process narrative by stating a fact like ‘The heart pumps blood‘ rather than adding complexity and teleological confusion by saying ‘The heart is for pumping blood‘?

Philosophers, believing they are providing a service to biologists by purging purpose from biological language, have concentrated on the ideas of ‘function’ and ‘adaptationism’ as ways of neutralizing contentious purpose talk. This has led to an elaborate philosophical industry that explores such things as Selected Effects Theory, Generalized Selected Effects Theory, Etiological Theories, Causal Role Theory, Neo-Teleology, teleosemantics, and more.^[48] But functional statements so important in all biology are critical in subjects like evolutionary biology, anatomy, developmental biology, molecular biology, physiology, and much more. If, as is claimed here, purpose in biology is real, then trying to exorcise teleological language is a vain enterprise.

When we replace teleological language with purely descriptive language something important is lost, the meaning is distorted, and the wonder of nature is diminished. If we replace ‘Flowers are coloured in order to attract bees’ with ‘Flowers are coloured and attract bees’ we find that the implied constraining aspect of adaptation as a consequence of ‘self-correction’ has been lost. Flower colour has not arisen in a chaotic way, it is not arbitrary, just happening to exist, it arose by a process of selection – albeit unconscious selection – governed by an evolved program, the genetic code. Many biologists continue to use teleological language while resisting teleology.^[6] Maybe it is time to accept teleology back into the biological fold.

Once we accept the use of purpose-talk in biology such philosophical mental contortions become of academic interest only.

Hard-nosed scientists have tried to avoid the real purposive character of living systems by resorting to what amounts to demeaning euphemism, using terms like: ‘neo-purpose’, ‘apparent purpose’, ‘goal-directed systems’, ‘hierarchically organized self-regulating systems’, ‘cybernetic systems with feedback’, ‘archaeo-purpose’ (Richard Dawkins), and ‘designoid’ (Richard Dawkins).^[5]

The word ‘teleonomy’ was introduced in 1958 by Colin Pittendrigh (a British-American biologist best known for his study of biological clocks) drawing attention to non-conscious goal-directed activity.^[13] Biologist Ernst Mayr pointed out that the ‘in order to’ of biological systems is not the consequence of mental intention but evolutionary function, suggesting the term ‘teleonomic’ be restricted to systems operating on the basis of a program of coded information.^[47] The list goes on.

Certainly, a distinction may be made between purpose as conscious intention on the one hand, and unconscious purpose as purpose that has arisen in non-conscious organisms as a consequence of natural selection. But this distinction only draws attention to the fact that consciousness itself was only made possible by the mindless purposiveness of natural selection.

Teleology did not arrive on Earth abruptly with the human intellect. Human intention is itself simply a highly developed aspect of the telos that pervades all nature. The mind is telos that has become self-conscious. Life and subjectivity ‘bubbled up from the bottom, not trickled down from the top‘ (Dan Dennett again) a point emphasized by the claim that ‘evolution is cleverer than you are‘.^[40] Human subjectivity does not account for or validate natural processes: natural processes account for subjectivity: ‘Human consciousness is an effect, not a cause‘.^[40] Again, in the Laws (10.903c) Plato declares ‘you perverse fellow . . . you forget that creation is not for your sake; rather you exist for the sake of the universe‘ drawing attention to the fact that we are a part of the universe not apart from it.

Deference to consciousness comes, in part, from the belief that everything in nature is a product of ignorant deterministic necessity, while consciousness can make choices, can exert free will. But the relationship between free will and determinism is a complicated and contentious philosophical matter. Can we say that the artificial selection of plants and animals based on human environmental factors is purposeful but the natural selection of plants and animals according to non-anthropogenic environmental factors is not? Does a prosthetic leg have a purpose because it is a consequence of human deliberation, while an actual leg only has purpose in a metaphorical sense?

Biological explanations will remain teleological because so many of them are about reverse engineering as we try to work backwards from functional explanations based on a process of selection. Talk of functions and functional analysis entails consideration of both future effects (teleology) and the evolutionary path of natural selection that gave rise to them (etiology). It is much easier to explain (teleologically) that a spider’s web is to catch flies than to recount the etiology of web-building. Yes, teleological explanations are ‘closer to us’ as shorthand accounts that save us the protracted process of enumerating the conditionally necessary antecedents required for a satisfactory causal explanation.^[28] But just because many organisms lack foresight and hindsight does not mean that they also lack reasons and purposes.

Aristotle & Darwin

Darwin once wrote to a friend that ‘Linnaeus and Cuvier have been my two gods, though in very different ways; but they were mere schoolboys to old Aristotle’.^[26]

Aristotle and Darwin were, in terms of their theoretical impact, the world’s greatest ever biologists, and they had much in common. Aristotle’s biographer Armand Leroi tells us they were both sons of physicians who escaped their fathers’ occupations by retreating into nature. They reaped the benefits of being both generalists and specialists at the same time, becoming familiar with the natural world in both its wide grandeur and dissected detail. Aristotle created biology (if not science itself) from scratch,^[27] and Darwin transformed our understanding of the living world and its history. Both agreed that the functional design we see in living organisms does not require either theism, mystical vitalistic forces, or intelligence.

Aristotle was a deist^[49] who resisted organized theism and was adamant that telos had nothing to do with human deliberation. He did not have a coherent concept of evolution (this was irrelevant to his account of natural teleology) although there were vague notions of selection in nature, even in his day. In noting that ‘Nature makes nothing in vain but always as far as possible for the best in respect to each kind of living thing’ (IA 704b15-18) he had, to all intents and purposes, described what today we would call functional adaptation. He also insisted that the goal-directedness that existed in organisms was not a response to a causal pull from the future, but a necessary application of explanatory over causal priority. His natural teleology claimed that like begets like for intrinsic reasons – the source of purpose in any organism stems from its inner nature.

Darwin then explained how functional adaptation rose out of many generations of mindless mechanistic interaction between organism and environment, combined with differential reproduction. Natural selection was an account of the way that variation was ‘selected’ (and therefore selected ‘for’), but it did not account for the variation itself. Darwin emphasized the long-term interaction of intrinsic (we would say genetic) factors and extrinsic (environmental) factors. In 1868 Darwin wrote ‘The whole subject of inheritance is wonderful‘. But neither man provided an answer to what became known as the ‘riddle of heredity’: that would have to wait until the genetic revolution in the 20^th century culminating in the deciphering of the genetic code in 1952 and what became known as the Modern Synthesis.

Darwin had ambiguous feelings about teleology, making various references to final causes^[31] but regarding the question of design as ‘insoluble‘. In 1874 he concluded a debate about design in nature that he had with American Christian botanist Asa Gray by agreeing that his evolutionary theory reinforced teleology. ‘What you say about teleology pleases me especially, and I do not think any one else has ever noticed the point. I have always said you were the man to hit the nail on the head.‘ He also wrote to his lawyer friend Thomas Farrer ‘(I)f we consider the whole universe, the mind refuses to look at it as the outcome of chance – that is, without design or purpose. The whole question seems to me insoluble,  . . . ‘

Paradoxically Darwin could not concede the Aristotelian goal-directed purposiveness of nature even though he had provided compelling evidence of the way it had arisen. Purpose and design in Darwin’s day was evidence for God – and that the agnostic Darwin could not countenance.^[37]

Aristotle is often regarded as the source of biological essentialism whereby kinds of things have uniquely shared essences that define what it is for them ‘to be’ – akin to the way that species created by God are unique and immutable. These species were referred to as natural kinds. Transitional forms were impossible: any variation would have to be aberrant or accidental. Essentialism is a complex notion with various interpretations^[50] but when Darwin insisted on the importance of variation much of essentialism was abandoned.

Aristotle pointed out that the purposiveness manifested by living organisms arises from their inner nature; Darwin explained how purposive inner natures arise out of the long-term mindless process of natural selection. Then, in the 20^th century, came explanations of the molecular underpinning of this purposiveness as information carried from generation to generation in the genetic code. Today we are trying to provide a coherent account of  ‘information’.

The problem of metaphor

For Aristotle telos was an inner principle of change that did not necessitate the use of anthropomorphic metaphorical language. However, there is no doubt that suspicion about teleology is encouraged by clumsy and obvious metaphorical language – the times when we use consciousness-talk (language used only for human psychological states) in a careless way in relation to non-conscious nature.

Example 1:
When we say that a particular trait is ‘favoured’ by natural selection we are using language usually reserved for conscious intention and applying it to a non-conscious process. Even so, the word ‘favour’ is frequently used by biologists in relation to non-human biology, so it is not exclusively a mind word within consciousness-talk.

A better example would be when we say that a river flowing down a mountain ‘wants’ to reach the sea. Clearly this is the metaphorical ‘as if’ language of human psychological states used in a lazy and mistaken way as applied to non-conscious nature. If this is what we understand by teleology, then clearly such usage can be usefully excised from scientific discourse.

But many cases are not clear cut: they are a matter of interpretation, of polysemy, in a world where none of us is semantically omniscient. There are times when it is a matter of interpretation . . . of perceived implication. So, for example, when we say, ‘Spiders build webs to catch flies‘ are we necessarily implying that spiders have human-like conscious intentions, and can therefore plan and anticipate the future? If so, then the accusation that teleological language is metaphor appears well founded, along with the desire to remove it.

Sources of order and purpose 6 – Teleological eliminativism –  natural teleology (purpose-talk in biology) is metaphor – it is empty. Having no referent in reality, it is both unscientific and unnecessary

Presumably, this is the kind of teleology Professor of Philosophy at Florida State University Michael Ruse had in mind when he pointed out in his book Darwin and Design: Does Evolution have a Purpose? (2003) that when we ask ‘What are eyes for?’ and ‘Is eyesight good?’ we are using ‘as if’ language: we are looking for goals in things that do not and cannot have goals because they are not conscious.

In musing about the most efficient and succinct way to denote the critical mechanism of evolution, Darwin no doubt struggled to find the most apt words to describe the process he had observed in nature that was so similar to human choice.  I have used the inadequate human metaphor of ‘self-correction’, a blatant anthropomorphism. Darwin used the human-intention-sounding word ‘selection’ . . .  a slightly less blatant anthropomorphism, softening its implicit subjectivity by employing the adjective ‘natural’.

Ruse acknowledges the difficulty of removing metaphor from biological language – that a doctor is being teleological when she tells a patient that he is anaemic, and that it is teleological to claim that bodies sweat and shiver to regulate body temperature. He states that purpose-like phenomena like these are ‘not there in reality’ but he recommends we continue using purpose-talk because it is ‘just part of the way in which we map reality in order to make sense of it’. In biology we are simply incapable of giving ‘an unvarnished report on reality’. The design and purpose metaphor is appropriate and fruitful because it gives us a ‘forward-looking kind of understanding’. And in his ‘On Purpose‘ (2018) ‘. . . something we might use to understand the world but is in no sense constitutive of the world‘. He expresses sentiments similar to those of physicist J.B.S. Haldane who declared that teleology is like a mistress ‘ . . . we cannot do without her, but cannot afford to be seen with her in public’. Ruse is not proposing teleological eliminativism (get rid of teleology), more a kind of teleological fictionalism (teleology is a useful fiction, a valuable heuristic device). On this view teleological language is a kind of shorthand that saves the tedious work of describing the developmental history of adaptations.

Professor Ruse keeps good company as he is also following in the steps of Immanuel Kant who addresses teleology in his third critique (1790), the ‘Critique of teleological judgment‘ in which he defines natural teleology as occurring when the parts of wholes are reciprocally both means and ends. Kant concludes that teleological language cannot be avoided. His argument is difficult to follow but it seems that though the design in nature implies a supernatural designer, such matters are beyond our science since faith is not knowledge, and Newtonian physics has no truck with final causes, so talk about purpose in nature can only ever be ‘as if’ talk.

Ruse neatly summarizes the state of play. Both Plato and Aristotle saw design and purpose in the world, Kant saw them as human projection. ‘Plato: God put purpose into the world – external teleology. Aristotle: purpose is part of the fabric of the world – internal teleology. Kant: purpose is heuristic, needed to do science but in itself of no ontological content – mind-given teleology‘.^[53]

Sources of order and purpose 7 – Teleological fictionalism – purpose-talk is a convenient explanatory tool or heuristic device, but it is only metaphor: it has no basis in reality

Based on all these cases we have, at best, only apparent purpose, and apparent design. Real design requires a designer (like God or a human designer), and Darwin had shown that there need be no real designer. And as Darwin had given a material account of how nature can give the impression of purpose without needing either the supernatural, or conscious intention, then there was only one conclusion. Purpose and design in nature is not real, it is our mental creation, an anthropomorphic metaphor. Purpose and real design are the products of human intention.

What is problematic about this account?

Diminishing nature

Well, we can look at this way. Eliminating purpose and design from nature brings living creatures closer to the inanimate world.

So . . . it might be argued. The purpose we ascribe to a chair as an object for sitting on is in our minds, not in the chair itself. The chair ‘just is’. So, we must approach biology in the same way. The purposes we see in nature are purposes added by our minds, so when we say that nature demonstrates design and purpose in its adaptations it is only ‘as if’ this were so. In reality, nature also ‘just is’. Insofar as organisms are the product of mindless mechanical processes then they are of the same status (in relation to purpose and design) as chairs, mountains, the wind, and the sea.

But clearly, we cannot say that nature ‘just is’ in the same way that a chair ‘just is’. Aristotle’s writings agree that the purpose of a chair comes from the human mind not the chair. He would also agree that nature does not have conscious intentions, and that its telos has not been instilled by an intelligent agent. None of the above cases remove the self-evident goals we see in all aspects of nature itself. It is these goals that make organisms very different from rocks.

On the one hand the teleology sometimes attributed to the actual process of natural selection (differential reproduction) can hardly be regarded as manifesting ‘aims’, ‘goals’, or ‘ends’. It is not natural selection that is purposeful, but its products, organisms are a different matter. It is worth repeating, once again, what has already been outlined several times already.

Organisms, are self-evidently purposeful, and not in a slight, incidental way, or metaphorical way. It is the competition between purposive organisms that created human bodies and brains. It is in this sense that natural selection is ‘cleverer than you are’.^[40]

How do we reconcile these two perspectives?

The answer is simple but difficult to grasp because of our traditional ideas and habits of language.

We assume that design must be the consequence of intellect. But clearly this is not so. A leaf is more intricately designed than any human artefact. This is real and natural design that dwarfs any human design. The insistance that design can only emanate from human minds, and that the design in nature is just the product of a mechanical Darwininian process, though true, is grossly dismissive of the process that created us.

There is indeed both purpose and design in nature, but it arose in a mindless way from an ignorant process. The subjectivity attributed to words like ‘purpose’ and ‘design’ and their relegation to ‘as if’ language when applied to nature are part of the long list of human presumptions about their place in nature that aggrandizes humans and belittles other creatures. It forgets that the mind is an effect, not a cause.

This takes us away from metaphor to a bioteleological realism interpretation of the spider’s web case above.

Example 2:
Spider webs manifest the purpose and design that has emerged mindlessly in the course of evolution. Only human minds (with the capacity for hindsight, foresight, and reason) can appreciate this purpose and design

The argument developed here is that the goals of nature are not conscious goals . . . but they are goals nevertheless, and they exist independently of human minds. We are in error when we associate web-building with spider foresight or intelligent design but, importantly, we are also in error when, as a corollary, we also deny a connection between web-building and catching flies. We make the mistake of assuming that only foresight, our minds, can provide a reason or purpose for web-building.  Because we humans, as reason-representers, are the only creatures that can understand nature’s reasons does not mean that these reasons exist only in our minds (Dan Dennett).

Mainstream science today still rejects the reality of purpose in nature because of the occasional blatant metaphor and the concern that teleology entails either an acknowledgement of divine intervention or the insertion of human subjectivity.

This seemingly trivial quibble has substantial consequences for metaphysics, our scientific perception of reality. Cases 1 to 3 suggest that organisms, their structures and functions, ‘just are’, in the same way that chairs and rocks in reality ‘just are’.

But the mode of existence of a living organism is very different from the mode of existence of a rock or chair.

When we say ‘The eye is for seeing‘ we are saying much more than ‘the eye sees‘. We are acknowledging that the ‘for‘ is a consequence of a selection process. Where there is selection, there is selection ‘for‘.  And, in nature, where there is an aim, a ‘for’, and a beneficiary, then there is clearly a purpose.

Darwin demonstrated that selection in nature does not require intelligence because it is ‘natural selection‘. The absence of conscious goals does not mean that teleology is a fiction. As an ignorant and mindless process natural selection can easily be dismissed as inconsequential, not real, but among its products are ourselves. Natural selection itself may be purposeless but its products are not. The purposes inherent in organisms existed in nature long before they were represented in human minds, and they are not apparent, they are real.

Aristotle would point out that teleology is the actualization of the pre-existing potential for form (today we would refer to this as the information contained in DNA) operating through conditional necessity to produce the physical structures and functions necessary for existence.

Unintelligent design

The argument developed in this article is that purpose and design in nature are a fact of the world, not a creation of our minds. Human art is often treated as the paradigm of design – yet how much more complex and intricate are the integrated functional designs we see in natural systems? A process that can produce something as amazing as the human brain deserves our respect. The human body and brain are far more sophisticated in functional design than anything ever produced by humans – and they are generated by a mindless process that is unaware of itself and its creations.

Our foray into teleology has revealed some of its many and protean faces. In the final analysis, we must decide which of the many applications of the word ‘teleology’ is most appropriate for science. Eight of the most popular candidates have been discussed here: theism, vitalism, chance, necessity, natural teleology, natural selection, teleological eliminativism, and teleological fictionalism. It is suggested that biologists follow the path of their mentors Aristotle and Darwin who each made major contributions to today’s scientific understanding of purpose and design in nature.

Deterministic regularities give the universe its order and design. After two millennia, following the analytic path of investigation promoted by the (mostly) naturalistic pre-Socratics, then Aristotle and the empiricists of the Scientific Revolution, we now understand the regularities inherent in nature much better than Aristotle could possibly have imagined. We could amaze him with a present-day explanation of why, to use his own words, ‘stars do not have feet’. The existence of non-conscious constraining physical laws in the universe means that ‘not just anything can happen’ and that outcomes or ends become, more or less, predictable and knowable.

Nature itself designed the community of life. But of course, it did not design with intention as we humans do. We see purpose in all aspects of nature, but it is not the conscious purpose of human deliberation. So . . . is nature’s design and purpose only apparent purpose and design? Do animals and plants have no more real purpose than a chair or the moon? The complex information transmitted between generations of organisms in the molecules of DNA would suggest otherwise.

Aristotle recognized not only the order that exists in inanimate nature, but also the additional unique kind of order we see in living nature, which has both aims and beneficiaries, albeit beneficiaries that are unaware of the benefits they receive. This has nothing to do with metaphorical language and human interpretation . . . it is part of nature itself. This is why Aristotle declared as absurd the idea that nature’s order was a product of the deliberating mind. Darwin was, of course, a modern who had no time for theism or vitalism even though he often described the operations of nature using the language of metaphorical human intention . . . words like ‘design’, ‘adaptation’, ‘selection’, ‘function’, and ‘purpose’.

The human mind has foresight, which most organisms do not possess. But absence of foresight does not equate to absence of purpose. Natural selection is an ordering process (a sorting algorithm) that occurs between living organisms and their environments, resulting in physical changes (adaptations) that our future-oriented minds can understand as beneficial or, as Aristotle said, ‘for the better’. The observation that ‘the purpose of an acorn is to become an oak‘ is not equivalent to the observation that ‘the purpose of a falling apple is to hit the ground’. Apples, when they fall, do not do so in an arbitrary way, they do so in a way that is constrained by the laws of physics. But organisms are, in addition, products of natural selection and therefore display the purpose that has been inserted by the unconscious process of selection ‘for’ something. This is necessity with umph!

Darwinism did not discredit teleology. It is a supreme irony that the expression ‘natural selection’ (which Darwin the atheist-agnostic used to name the process that would transform our understanding of the world) contained within it the very teleology he found ‘insoluble’.

To express the essence of evolution Darwin the biologist, like biologists today, resorted to language reminiscent of conscious intention. ‘Selection’ is the metaphorical language of conscious choice. And yet by the addition of the adjective ‘natural’ Darwin had, we now realize, successfully isolated the unconscious purpose exhibited by organisms themselves. Darwin had expelled intelligence from ‘intelligent design’, even though the design remained. He had given a naturalistic account of the way that natural teleology had arisen.

Neither Aristotle nor Darwin had a scientifically adequate account of heredity, but this did not weaken their cases. Biological purpose arises from the interaction between organisms and their environments over many generations: it is unrelated to human foresight or hindsight. We do not need a new word ‘teleonomy’ to simply recapitulate what Aristotle was at pains to assert himself and the fact that design and reasons emerged from matter in a deterministic way as described by Darwin has no bearing on this.^[4]

Commentary

The discussion above has investigated the idea of teleology and its place in the thinking of the world’s greatest biologists, Aristotle and Darwin. It is now time to summarize what has been a lengthy discussion. The section on bioteleological realism is a concise account of the historical development of the notion of teleology, while the epilogue provides a simple summary of teleology and contemporary. biology.

Bioteleological realism

Aristotle had no doubt that purpose in nature was real, it existed within nature itself; it was not a creation of God, and it was not inserted by the human mind as metaphor or simplification. The ‘beneficial’ effects we see in nature (adaptations) did not arise by either chance or necessity, but by natural design.

Darwin realized that to ascribe purpose to nature might, in the popular mind, imply the activity of God. He therefore remained uncommitted in his public views on the matter while his work, in fact, provided the physical mechanism that was lacking in Aristotle’s purpose.

In examining the work of these two men I have mounted a 21st century defense of Aristotle’s natural teleology as bio-teleological realism, the claim that there are mind-independent purposes in nature.

Darwin described how eyes and legs, leaves and spines, arose in nature in a causally transparent way as adaptations that were ‘for’ walking, seeing, food production, and deterrence. They were also ‘for’ without human or supernatural foresight. He did not explain purpose away, he simply gave it a naturalistic explanation. Purpose was not imposed from outside by humans (as cognitive metaphor) or as a supernatural gift from God: teleology existed in nature itself. The purpose of a prosthetic leg is established by the intentions of its inventor. Legs that occur in nature also have purposes, even though they were created mindlessly by a natural process that has no conscious intentions. Moreover, the idea that purpose in nature demands the foresight present only in humans is simply mistaken. It arises in nature through the adaptive feedback of natural selection; it does not require the foresight we associate with consciousness. Aristotle’s final causes make sense. Nature can be ‘for without foresight’.

The concepts of order, design, and purposeful agency are central to our interpretation, often religious, of the natural world. Investigating the meaning of these concepts has taken us on a historical journey through ancient Greek natural philosophy and the origins of science, religious interpretations of the world and its meaning, the Scientific Revolution, the theory of evolution, and the modern-day philosophy of biology and language.

Our ancient ancestors believed that the world was imbued with spirit, while ancient, medieval, and modern theists believed that God(s) was present in all things (omniscient, omnipotent, omnibenevolent, and omnipresent). Religious belief was usually interpreted in human terms: the universe, its processes and contents, were personified and anthropomorphized.

For Plato, the order we see in the world was superimposed extrinsically on everything by the Demiurge. In contrast, Aristotle’s emphasis was more on the physical world, and especially that of living organisms and the internal formal cause that ensured that like begets like. For Aristotle, the purposeful function and design so evident in all organisms originated from within them as potential to be actualized in the future. This was intrinsic goal-directedness.

Aristotle’s natural teleology did not imply backward causation: it was not anthropomorphic or theistic, nor was it a mere explanatory tool used to back up materialist-mechanist causal explanations. His telos was not conscious planning, or the intention we associate with the human mind, it was more to do with the culmination of processes that follow a predictable path. Final causes ‘ . . . function quite literally as the direction-givers and the ends and limits of developments necessitated by formal-efficient and material-efficient causation . . . This does not mean that final causes have only a heuristic value . . . in demonstrations of the teleological type the final causes are part of the conclusion that is being demonstrated, the practice of Aristotle’s natural science demonstrates the very existence of natural teleology.’^[42]

In the Christian Middle Ages intellectual life was strongly focused on final causes or purposes, about why things occurred (usually a metaphysical or religious question) rather than how they occurred (an empirical or scientific question). Medieval Scholastics blended Platonism with Aristotelianism and Christian theology. Aristotle (known as ‘The Philosopher’) was studied by Thomas Aquinas when theology was preoccupied with the end of things (known as eschatology) which entailed close analysis and interpretation of the biblical text – mostly the Book of Revelations – in a discussion of the afterlife, heaven and hell, the second coming of Jesus, resurrection of the dead, the last judgment, the world to come, and much more. Here was Christian teleology as an answer to the question ‘How will it all end?’ and it presented Christians with the powerful imagery of the Armageddon or Apocalypse as the final mighty clash between the armies of good and evil at the Omega point, the end of time. Needless to say, all this is a long way from Aristotle’s telos. Put simply, Medieval Thomist Scholastics united Christian theology with both the extrinsic Platonic idea of a transcendental Demiurge, the intrinsic teleology of Aristotle, and the Islamic theology of Avicenna and Averroes. All was combined into a characterization of God’s divine plan for his Creation.

In the Early Modern period (c. 1550-1750) teleology was at the heart of a growing intellectual divide as the Western world began its move from a religious to a scientific grand narrative. Eager 16^th century mechanistic scientists wanted to shake off the traditional deference to both the classical intellect and Biblical authority. Aristotle was an ancient and increasingly irrelevant figure to be torn down as part of the process of starting afresh.

With the advent of mechanistic, materialistic, and experimental science came criticism of Aristotle from powerful intellectuals like Francis Bacon (1561-1623), Robert Boyle (1627-1691), Rene Descartes (1596-1650), Thomas Hobbes (1588-1679), the later John Locke (1632-1704), and Baruch Spinoza (1632-1677). Formal and final causes fell out of favour. Treatment of nature in anthropic terms – endowing trees, mountains, animals, and plants, with non-divine agency was frowned on.

All-in-all the Scientific Revolution over-extended its antipathy to non-human and non-divine agency by exorcising purpose (teleology) from living organisms altogether. And, as a result, living organisms, lacking conscious deliberation, took on the character and purposelessness of inert matter.^[52] The living was subsumed to physics and chemistry in an ambience of thought that has persisted to the present day . . . agency as physicochemical process.

Aristotle had made blatant scientific mistakes and errors that appear ludicrous today. He propounded a theory of spontaneous generation, promoted a strongly hierarchical view of the world as a scala naturae, misinterpreted the heavens, and believed the heart was the seat of intelligence, emotion, and sensations. He had, the moderns pointed out, depended too heavily on deductive logic rather than experiment and observation. Though true, this accusation ignores Aristotle’s firm belief in observation. His dissection of organisms and concern for sound procedural principles demonstrated an acute analytic scientific awareness. Leroi, Aristotle’s biographer, suggests that Aristotle ‘invented science from scratch‘^[21] Even as the world’s greatest ever polymath he would, in the fullness of time, inevitably be surpassed by those who stood on his shoulders.

Science continued its investigation of material order and pattern and for most people, scientists included, the design evident in nature still pointed directly to God. Science had nothing to say about the purpose so evident in all of nature.

The influential 19^th century English clergyman William Paley expressed the general view of his day in the book Natural Theology (1802) which asserted that the obvious design we see in the natural world was irrefutable evidence for the hand of God. Just as we attribute the order and purpose of a watch to the watchmaker, so the design and purpose we see in nature was a consequence of the divine Maker of the cosmos.

Then, in 1859, Darwin’s theory of natural selection provided a naturalistic answer to questions like ‘Why do birds have wings?’ Birds had wings because the historical development of wings had conferred a selective advantage on those creatures that possessed them. Like Aristotle’s natural teleology, Darwin’s natural selection did not invoke either theism, vitalism, or anthropomorphism even if he, and later scientists, continued to use anthropocentric language. Aristotle’s ‘inner principle of change’ sounded to many scientists like vitalism, or theism, or both. Darwin had, it was believed by many, drawn both Creationism and teleology to a close.

The ‘survival of the fittest’ was an expression coined by social Darwinist Herbert Spencer in his Principles of Biology (1864), his pithy summary of Darwinian theory. Alfred Russell Wallace suggested to Darwin that Spencer’s phrase was preferable to Darwin’s own incendiary choice of the words ‘natural selection’ to summarize his grand theory. Wallace considered it imprudent to imply that nature can engage in conscious choice. Darwin did not accept Wallace’s suggestion outright, but he did acknowledge the pervasive use of metaphor in describing nature and, eventually, Spencer’s words appeared in the fifth edition of On the Origin . . . which was published in 1869. On p. 72. he states, ‘I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection, to mark its relation to man’s power of selection. But the expression often used by Mr. Herbert Spencer of the ‘Survival of the Fittest’ is more accurate, and is sometimes equally convenient.’ Though perhaps more palatable, Spencer’s words had their own problem, needing a reference to heritability if tautology was to be avoided.

Evolution is now universally accepted within the scientific community but teleology, so full of metaphorical language and religious associations, is generally regarded as an ancient, outmoded, and ambiguous idea promulgated by the mistaken Aristotle. Teleological language, it was assumed, may have some explanatory value, but teleology itself has no foundation in the real world and is therefore of little consequence for modern science (see the quotes at the head of this article). However, it is argued in this article that Baconians of the Scientific Revolution, in their desire to start anew, had over-reacted to religion and the ancient anthropomorphization of nature. This rebellion has remained with us.

What is still not acknowledged is that Darwin did not explain teleology and design away: he gave them scientific credibility.

Aristotle summarized his work in biology by using an uncharacteristically mystical and poetic phrase. From 2000 years ago he passed to us the message that all living things ‘partake in the eternal and divine‘. Darwin would never have made such a statement. We are tempted to smile and allow Aristotle a momentary and moving literary flourish, but this would be a mistake. His scientific investigations began with the examination of change and the paradox of permanence in change. One pillar of his teleology was the observation that though individuals perish, their form persists from generation to generation . . . what today we might call the immortality of our genes. To the Greek mind, and ours, immortality was equated with the divine. The most natural function of living things is to produce others like themselves – and in so doing they are immortal, participating in the eternal and divine. Nothing that is perishable is able to ‘remain the same and one in number’ but through reproduction it ‘remains not the same, but like the same, not one in number but one in form.’ (Anima II, 415a23-b7).

In sum, the intricate design and purpose we see in nature is self-evident, greatly surpassing any human attempts at design.^[39] If this design is not imposed from outside by some intelligent or vital force – and not mapped onto the world in some way by the human mind, then it must have arisen from within nature itself. Species-specific designs are repeated from generation to generation, again and again in a path-dependent way. Design in nature produces functional adaptations that are ‘for the good’ or ‘for the better’ and goals or ends with beneficiaries are acceptably referred to as purposes. None of this entails the supernatural or mind-dependent metaphor. All of this was well known and clearly stated by Aristotle who called it telos . . . but 2000 years would pass before Darwin eventually provided a scientific account of the origin of this intrinsic goal-directedness.

Our confusion arises from what philosopher Dan Dennett has called Darwin’s ‘strange inversion of reasoning‘, our refusal to accept that natural selection is ‘for without foresight‘ (me) producing organic wholes that are ‘competent without comprehension‘ (Dennett) . . . that purpose ‘bubbles up from the bottom, not trickles down from the top‘ (Dennett).

When Richard Dawkins states that biology is ‘The study of complicated things that give the appearance of being designed for a purpose’^[56] he is making a statement that uncompromisingly links ‘purpose’ to ‘conscious intention’. In doing this he ignores the way teleology is firmly embedded in both biological discourse and nature itself, and he joins those who consider the investigation of function in biology as a matter of heuristic convenience. In so doing he restricts the word ‘purpose’ to human intention, downplaying the miraculous purposive achievements of natural selection (including ourselves). In a bid to exorcise from biology any hint of the Argument from Design he has thrown the baby out with the bathwater.^[57]

Because we usually encounter design and purpose as a consequence of human planning (which includes hindsight and foresight) this does not mean that purpose in nature cannot be real. Limiting purpose-talk to situations involving human subjectivity renders natural teleology, by definition, a human construct. This article has argued that teleology did not arrive on earth abruptly with the human intellect and that purpose and design in nature are real; they are part of the fabric of the natural world, not a creation of our minds, and that is why attempts to purge biology of purpose-talk have failed. Though consciousness-talk is, on occasion, used as metaphor in biology this does not mean that there is only apparent purpose and design in nature. Design and purpose in nature are not metaphorical but literal.

To remove teleology from biology is not just the harmless elimination of metaphor, it is a reduction that diminishes our biological understanding of what exists in the texture of the world. It places living matter on a similar footing to inanimate matter in the realm of purpose, design, function, and value (making the distinction between human values on the one hand, and facts of science on the other, appear clear-cut), and diminishes the wonder of what natural selection has created.

This is not just a semantic debate about what we mean by the word ‘purpose’; it is a metaphysical argument about what exists in ‘reality’.

In summary: goal-directed behavior is a property of biological systems, just like any other biological property (it does not imply backward causation, even though explanations proceed from goals); it does not necessarily imply conscious intention; as a behavioral orientation it expresses value in the sense of leading to some outcomes rather than others. For the same reason, it underpins, but does not determine, moral discourse and behavior.

It is OK to ascribe purpose and design to nature, and to use the word ‘for’ in explaining biological function.

© Roger Spencer 19 June 2018

Key points

• The study of purpose is called teleology, and it can relate to anything

• The study of purpose in living organisms is called natural teleology or bio-teleology

• This article argues the case for bio-teleological realism – the view that purpose in nature is best regarded, not as metaphor, but as existing or imminent within living organisms themselves

• If evolution is mostly gradual change that builds on existing forms, then we might expect the ideas that represent this evolution to grade in a similar way. Purpose in nature is such an idea. Purpose emerges with the order and regularity of nature. This order has cause, and a cause is ‘for’ something. But order is not purpose in its most developed form – it is rudimentary, primordial, or archaic purpose. Adaptations of living organisms are ends that arise by design: they are ‘for the better’. Does this then count as purpose? It is argued here, with Aristotle, that absence of deliberation does not necessitate absence of purpose – that the semantic restriction of ‘purpose’ to ‘conscious purpose’ is a human arrogance that diminishes the conscious purpose that evolved out of the purpose already inherent in nature

• We are inclined to think of purpose in terms of conscious human intentions (or possibly the intentions of supernatural beings)

• There are nine major theories about natural teleology and its source: theism, vitalism, chance, necessity, Aristotle’s intrinsic natural teleology, Darwinian natural selection, teleological eliminativism, and teleological fictionalism, and bio-teleological realism

• We tend to explain biological systems more in terms of the future than we do physics or chemistry because organisms are a consequence of natural selection, selection being ‘for’ something, the ‘for’ usually entailing a beneficiary

• We accept intuitively that living organisms affirm existence over non-existence, life over death, and for this reason they have ‘interests’ or functions that make purpose-talk (like ‘plants have scent to attract pollinators’) acceptable when we would not accept a similar statement in physics or chemistry (‘the apple falls in order to hit the ground’)

• Socrates interpreted the complex and finely-tuned purposive design that is pervasive in nature as evidence for an external grand designer or God (The Argument from Design) discussed today as Intelligent Design. Plato referred to this supreme external designer as the Demiurge

• Aristotle agreed that there was purpose in nature but he thought that it derived, not from an external source, but from within living organisms themselves

• Charles Darwin’s theory of natural selection provided a coherent explanation for the diversity of organic life without recourse to external agents. His theory was revolutionary because: it removed the necessary requirement for God and a divine plan for the Creation; it implied that humans were descended from apes; it attacked the assumption of humans being at the pinnacle of life in a Great Chain of Being arranged from high to low; it suggested that the organic world had arisen in a mechanical and ‘mindless’ way

• Natural selection appeared to remove the need for either intrinsic or extrinsic teleology, teleological language being interpreted as the mistaken imposition of human conscious purpose onto the world as metaphor. Plants, for example, do not have conscious intentions. Teleology was therefore regarded as a mistaken metaphysical theory. Biologists were therefore encouraged avoid teleological language by expressing it in a non-teleological form

• In spite of Darwin’s great insight and the awareness of the pitfall of the consciousness metaphor, biologists have continued to use teleological language, noting that natural selection, though unconscious, is very like conscious-purpose-like intentionality. Various names have been suggested the most popular being ‘teleonomy’

• Though teleonomy is an unconscious process its similarity to conscious intention, the fact that it exists in nature itself and is not a product of the mind, and that it has given rise to all the complexity of biological organisation (including the brain and consciousness) warrants the use of purpose-talk which (following common usage) should be accepted as legitimate practice: it is neither metaphor not scientific error

• Today’s problem is how to express the mind-independent reality of teleonomy without using the metaphorical language of conscious intent. How can we avoid the pitfall of interpreting the error of metaphor as proof of the unreality of the phenomenon itself?

• We do not have to assume that the purpose-like character of living systems was inserted by either God or the human mind: mechanical and mindless natural selection is both necessary and sufficient. The problem is that we are constrained by language. Words like ‘design’, ‘adaptation’, even ‘selection’, and ‘purpose’ are all consciousness-talk and therefore metaphor when applied to any non-sentient object. This is not a failure of reality but a failure of language

• If teleology were just a matter of word definition and the ‘the meaning of a word is its use’ then we must accept that in both common parlance and scientific discourse ‘purpose’ is used in ways that do not entail consciousness

• Similarly the teleonomic statement that the purpose of living organisms is to ‘survive, reproduce and flourish’ should be treated as a self-evident biological axiom

• The above biological axiom also has normative weight as a statement of ultimate biological value akin to Aristotle’s final cause

• The implication of this for human ethics is discussed in the article ‘Morality and sustainability’.

Teleology timeline

BCE

Pre-history – Animists believe that spiritual forces inhabit the physical world and animate living organisms
2375 – The Egyptian Old Kingdom societies believe in opposing universal forces, Ma’at as Order and Isfet as Chaos
624-469 – Pre-Socratic natural scientists seek the source of order in the world in the fundamental elements of Earth, Air, Fire, and Water
570-495 – Pythagoras refers to the ordered universe as Kosmos
500-428 – Anaxagorus teaches that the world is the product of an intelligent principle he calls Nous
470-399 – Socrates argues for the existence of God based on the self-evident presence of design, the Argument from Design
460-370 – Democritus claims that the world is composed of indivisible atoms and that these have, by chance alone, combined to form the physical objects of the world
410 – 370 – Hippocrates, founding father of medicine, teaches that the human body is animated by an inhabiting vital force
428-348 – Plato maintains that the order we see in the world is a consequence of an ‘ordering principle’ created by a God-like Demiurge
1728 – The word ‘teleology’ coined by German philosopher Christian Wolff, derived from the Latin form teleologia and the earlier Greek telos
1859 – 24 November – Charles Darwin publishes On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life
1958 – Colin Pittenrigh coins the word ‘teleonomy’ to distinguish between mindless goal-directedness in nature and conscious human intention

First published on the internet – 1 March 2019
. . . 5 June 2021 – minor revision
. . . 20 August 2021 – overall review
. . . 27 August 2021 – minor revision
. . . 5 March 2022 – added Epilogue
. . . 9 April 2022 – added updated Epilogue
. . . 5 August 2022 – Epilogue update
. . . 4 August 2023 – minor edit

The Community of Life
Showing biological divisions, geological ages and major evolutionary events
Courtesy Evogeneao https://www.evogeneao.com