Do We Need Purposes in Biology?

Emily Dickinson often had a rather chilly view of things. Around the end of the Civil War, five years after Charles Darwin had published his Origin of Species, she wrote this short poem about the life of worms:

Our little Kinsmen—after Rain
In plenty may be seen,
A Pink and Pulpy multitude
The tepid Ground upon

A needless life, it seemed to me
Until a little Bird
As to a Hospitality
Advanced and breakfasted.

As I of He, so God of Me
I pondered, may have judged,
And left the little Angle Worm
With Modesties enlarged.

Notice how, right at the beginning, the poet identifies us humans with worms. Things only go downhill from there! The worms are gobbled down by a bird, and much the same seems to be said of our relationship with God. I doubt the suggestion is that God likes a good human flank steak. Instead, the point is this: As we see the worm has a purpose, so God sees that we have a purpose; but just as the purpose of the worm has no connection to the worm’s wellbeing, so our purpose seems not to have much to do with our wellbeing.

Now, I don’t want to go into a detailed discussion of the full meaning of the poem. (What does Dickinson intend by “modesties enlarged,” for instance? Does that give us a break?) Rather, I want to pick up on the structure of Dickinson’s reasoning. The worm’s existence has meaning when we see that it exists in order to be food for the bird. The same for us with God. The purpose of the worm — its end — is to feed the bird. Our purpose, our end, comes from God’s needs. (That is what makes the poem chilly, because we often think God focuses on our needs.) Notice what is going on: Normally, when we consider the way things in nature exist and are connected with other things, we think in terms of what philosophers call “efficient causes.” The bird is hungry; it sees a worm; various physiological processes kick in and the next moment the worm is on the breakfast menu. Dickinson isn’t quite thinking this way. She is putting the worm before the bird, one might say. Why does the worm exist? In order to feed the bird. That is the worm’s purpose.

Leave aside whether biologists would agree with Dickinson’s reasoning here. I want to point out that we seem to have a reversal from what happens in the case of efficient causes. Instead of hunger explaining why the bird feeds, the nature of the worm explains why the bird acts to satisfy its hunger. In other words, instead of having the hunger cause the feeding, we have the bird’s behavior being explained — i.e., caused — by the worm. The order of explanation is reversed: not causal event (hunger) to future effect (feeding), but future goal or purpose (feeding) to past phenomena (hunger). This is what is known as “final causation” or teleology.

But what happens if a cat suddenly jumps in and kills and eats the bird? Clearly, the bird would not be able to eat the worm, and so the worm’s purpose — or telos — would not be realized. Here’s the rub: in the case of teleological causation, there is no guarantee the goal will be attained. You cannot say that if there is a worm there necessarily will be feeding, even though the worm exists in order to feed the bird; only time will tell. From the modern scientific perspective, this may not seem like a very satisfactory type of explanation. We want to be able to predict with accuracy what will happen, not what tends to happen but very well may not.

Such problems involving causation have occupied thinkers at least since the ancient Greeks. Beginning with modern science, “final causes” have proved particularly controversial. Some scientists and philosophers have suggested we just stop thinking and speaking this way and stay with efficient causes. In fact, already in the time of the ancient philosophers, the atomist Democritus expressed such a view. Several centuries later, his follower, the Roman poet Lucretius, wrote scathingly of final causes that,

… explanations of this type …

are back to front, due to distorted reasoning

… all the things which were first

actually engendered, and gave rise to the preconception of

their usefulness later.

Primary in this class are, we can see, the senses and the limbs.

Hence, I repeat, there is no way you can believe

that they were created for their function of utility.

But dropping final causes may be easier said than done. In the world of evolutionary biology, in particular, there is still a huge amount of final-cause thinking, despite the fact that Darwin is often said to have done away with teleology. Why does the stegosaurus have diamond-like plates running down its back? In order to control body temperature, cooling in the heat and catching sun in the cold (no small issue for a cold-blooded organism). The plates exist (or rather used to exist) in order to — for the purpose of — controlling the temperature. You don’t get this kind of thinking in the physical sciences. In physics, objects don’t have any purposes; we don’t need to appeal to the final goal or purpose of the moon, for instance, in order to explain it. (If the sardonic suggestion is made that the moon exists in order to light the way home for drunken philosophers, you know that is a joke.) But if physics can do without final causes, why can’t biology?

The worries about final-cause thinking increase when one looks at some of the purposes to which it gets put. Are final causes the thin end of a wedge that, when driven in, gets us into religion, perhaps even the Christian religion? You think you are doing paleontology, unearthing the characteristics of animals and plants, but truly you are in the God business, revealing His ultimate designs. Plato and Aristotle lived centuries before Christ, but their views about final causality came to influence later Christian (as well as other religious) thinkers.

Plato suggested that the key to purpose-like thinking is that the world was designed by an intelligent being — something that in the Timaeus he called the “Demiurge.” Aristotle believed in an ultimate deity, the Unmoved Mover, but had no sense that this being did any designing. Indeed, He (or She or It) seems almost oblivious to earthly existence, as it contemplates its own perfection. But, in some sense, Aristotle thought there must be some kind of drive or force directing everything in nature toward their intrinsic ends. Ultimately, he thought this drive could be explained by a natural impulse to draw nearer to the Unmoved Mover. Whether this tendency in things is construed as something actual — a kind of occult force — or a principle of ordering, we have goal-directed activity. I wouldn’t say that this forces the Christian God on you, but the natural world of Plato and Aristotle is a lot more spirit-infused than it is under the Cartesian philosophy, where matter is just lifeless extension — res extensa.

As a matter of fact, this type of final-cause thinking was the basis of the so-called argument from design, used by Catholics like Thomas Aquinas and Protestants like Archdeacon William Paley to demonstrate the existence of God. Paley famously used the analogy of the watch. Why does a watch have a short arm and a long arm? Because someone designed it that way so that it could tell us about hours and minutes, The arms exist for the purpose of telling the time. By analogy, the stegosaurus has those plates because the Great Zoologist designed them to be the way they are in order to control heat.

I don’t want to say that final causes — whether understood as external teleology (as in Plato) or internal teleology (as in Aristotle) — are silly or useless. However, such thinking does run into philosophical problems, especially when put to work proving the existence of God. The philosopher David Hume pointed out that there are all sorts of things that call for final-cause thinking, and which nevertheless seem to point not to a perfect designer, but to a rather nasty one. As Darwin worried, what about the adaptations of parasites that cause so much discomfort to the hosts? In Emily Dickinson’s poem, however “enlarged” its “modesties,” the worm doesn’t fare so well. At the very least, how do we know that the designer in question is the singular all perfect creator-being revealed in the Abrahamic religions and not, say, a committee of super-designers? Is the analogy between the universe and a watch even plausible to begin with? As for internal forces, what is the empirical evidence for them? Are they spirit clouds hovering over everything in nature rather like the fog over the meer in the Sherlock Holmes novel The Hound of the Baskervilles? If so, why should modern science care?

Breaking with tradition, Immanuel Kant argued in the eighteenth century that final-cause thinking is essentially heuristic: final causes don’t exist out there in nature, but are instead something we impose on nature to make sense of things. We may appeal to purpose or function of temperature control when interpreting the stegosaurus plates, but that doesn’t mean that these purposes actually subsist outside our minds. Maybe Kant was on to something. But where he fell short was not explaining why final-cause thinking is appropriate and even necessary in the case of biology — to explain organisms, for instance — and not physics. Why can we talk of the purpose of the stegosaur fins but not of the moon? Kant was not like Democritus or Lucretius, sneering at the use of final causes, though he did agree with these ancients that such causes lack objective existence. In the end, Kant gave up, declaring that “it is absurd … to hope that another Newton will arise in the future, who shall make comprehensible by us the production of a blade of grass.” One suspects that Kant really thought that God was behind it all, but his philosophy forbade him introducing God into these kinds of discussions in an explanatory way. One also suspects that Kant’s Pietist background, with its stress of faith over reason, may be important here.

Charles Darwin added the missing piece. His mechanism of natural selection didn’t just introduce change into the biological picture. It introduced change of a particular kind, namely natural processes that produce features that look design-like. In the Darwinian account, if natural features, such as the stegosaurus’s plates, weren’t design-like, they wouldn’t help their possessors survive and so they would lose out in the “struggle for existence.” Contrary to popular representations, Darwinian change is not higgledy-piggledy but orderly (if not designed). As Darwin himself puts it:

How have all those exquisite adaptations of one part of the organisation to another part, and to the conditions of life, and of one distinct organic being to another being, been perfected? We see these beautiful co-adaptations most plainly in the woodpecker and mistletoe; and only a little less plainly in the humblest parasite which clings to the hairs of a quadruped or feathers of a bird; in the structure of the beetle which dives through the water; in the plumed seed which is wafted by the gentlest breeze; in short, we see beautiful adaptations everywhere and in every part of the organic world.

The answer is natural selection. So here we have the reason why final-cause talk is permissible and necessary. Thanks to the processes of evolution, organisms appear design-like, even though they are ultimately the result of random variations plus natural selection. In order to make sense of this fact, we often think and talk in terms of ends or purposes, although these ends or purposes don’t actually exist in the real world. So in a sense, Kant was right: teleological thinking is heuristic, something imposed on the world by us. It is no less useful or legitimate for all of that. Physics doesn’t have need of final-cause talk because, not having been produced by natural selection, the objects of physics do not appear designed in the same way.

While this takes God or occult forces out of the scientific picture, don’t think that going this direction means that all is secular or meaningless — Kant and Darwin today, Richard Dawkins tomorrow. Far from it! The believer can continue to see nature as God’s creation and natural processes as God working His purposes out. It is just that God does it through evolution, rather than by intervening miracle. Moreover, something that remains important for both the believer and the non-believer is whether final-cause thinking (understood heuristically) applies not only to the natural world but also to the human context. Can we treat human reasons as final causes?

I have my opinions on this but now is not the time for them. Suffice it to say that, thanks to Darwinian biology, we have a good solution to a major problem in the history of philosophy, but like all good solutions it opens up new questions and challenges. That is what makes it all so very worthwhile to be a human being and why I, for one, much as I love Emily Dickinson’s poetry, am not about to buy into her rather gloomy and cynical view of our place here on earth.

12 Responses

  1. jack stephens says:

    We have to explain why we humans are motivated by visions of ideal states toward which we strive. Religious people try to align themselves with to the visions of their particular beliefs. Others strive for other visions of economic justice, the “Singularity”, etc. We seem to find our present state to be somewhat out of kilter and feel it needs to be corrected in some way, and it has probably always been that way. You might say that our species is the unsatisfied animal. Even billionaires are not satisfied to just enjoy their riches.

    • Michael Ruse Michael Ruse says:

      I don’t personally know any billionaires so I cannot really speak for or of them, although I suspect there might be a difference between those who inherited their wealth — and who might just enjoy the comfortable life — and those who made their wealth — and who I suspect will always be driven and looking for new things to do or conquer. This question does raise for me what is an interesting and important question: to what extent, in the end, do religious and non-religious people have different ends and purposes? Obviously on the surface, the Pope and Richard Dawkins are on very different tracks, but what strikes me is the extent to which they are both very moral men, really concerned about human beings and how to make things better. Their prescriptions are very different, but they have much more in common than with someone whose only aim in life is having money and lots of girlfriends (or boyfriends) and so on and so forth.

  2. Natural selection is to designate random chance by numerous, successive, slight modification over long periods of time as the designer instead of The Designer. It is “intelligence” replacing “Intelligence.”

    • Michael Ruse Michael Ruse says:

      Yes, but although I am a non-believer, I don’t think that intelligence rules out Intelligence, or vice-versa. I think it is quite open for a Christian (or Jew or …) to believe that God created through unbroken law and that that law was natural selection. I don’t believe in the Christian God on philosophical grounds — the problem of evil — and theological grounds — the incompatibility of the Jewish and Greek heritages — not because of science. If we are indeed made in the image of God, then finding out science is the greatest proof of this.

  3. David Wilson says:

    This entire evolution/intelligent design/creationism argument suffers from a fundamental flaw. That flaw is that the Bible says God created life on this planet and then created man. This is a “what” statement saying what God did.

    When you start talking about evolution in relation to this you now encounter two issues. The first issue is that the Bible never makes a “how” statement. The Bible says God created life and that he created man, but the method or process used is never discussed Evolution, on the other hand is a process. It says less what happened and more of how does it happen. Evolution is a “how” statement. Is there some possibility that God created man and used evolution to accomplish the creation of life or man? Certainly.

    The greater issue that seems to be never discussed is how was life created in the first place. Anyone who has studied biochemistry knows that life is extraordinarily complex and involves information storage and replication at its very core. When most people think of life starting out in the primordial soup, they think of energetic discharges yielding amino acids, fats and so forth, that self assemble to form lipid bilayer sacs filled with more soup that eventually yields enzymes and such. This seems like a bit of a reach, but when you have billions of years, who really knows. The critical question, however, is, assuming enzymes and such could be created this way, how does the information present in the amino acid sequence become recorded in DNA or some other medium and how is that recorded information then duplicated or read such that the proteins can be replicated?

    The fact of the matter is there simply is no credible theory as to how life could be created. Some claim it arrived on asteroids, but that is a transport issue and not creation. Others come up with hand waving arguments about how the initial enzymes were made from DNA, but there is little to no proof for this – only hopeful wishing.

    Ultimately, the argument about trying to reconcile or deny the “what” statement of God creating man or life with the “how” statement of evolution is not only illogical and impossible to logically argue (akin to demanding that we believe the dinner you are eating was not made because a specific recipe was not followed). The real question that no one has yet to find an answer is just how did life become created and, in that argument, God has a monopoly.

    • Michael Ruse Michael Ruse says:

      Personally, I think the origin of life question — which is made much of by critics of Darwinism like Thomas Nagel and Alvin Plantinga — is a red herring. We don’t have the answer yet, but I am sure it is on its way. We know so much now about DNA and RNA and also about the creation of planets and so forth, that I am sure an answer is there and will be found. It is way more difficult than we thought fifty years ago, but interesting questions are difficult. More than that, I don’t think it makes a ha’porth of difference theologically if life is mechanical or not. Being a good person has nothing to do with this.
      This said, I think there is an interesting question here, one made much of by Thomas Nagel in his Mind and Cosmos. This is the matter of consciousness. I think this is the big problem and frankly I don’t even know what an answer would look like, let alone what it is. This is the difference between this and the origin-of-life question — I know what an answer to the origin of life would look like — RNA was formed by crystallization or some such thing. I don’t think ignorance here means that Darwinism doesn’t work — I differ from Nagel on this point — I don’t know the full meaning of gravity but it doesn’t mean that Darwinism doesn’t work, even though we need gravity to explain (let us say) why there will never be a cat the size of an elephant (because the legs would not be strong enough).
      Like many philosophers today, including Nagel, increasingly I am being drawn towards some form of panpsychism — consciousness is part of matter itself — this doesn’t mean that stones think, or plants either — despite the views of the Prince of Wales who plays music to his plants — but I do think in some sense it emerges naturally as part of the evolutionary process and is not miraculously inserted at some point in the process.
      Of course the big question is that of worth. I am a total naturalist, but as a teacher I have always taken most seriously my Quaker heritage about believing in that of God in every person (for me, taking this in a secular way) — the spark of being — has been the ruling force when dealing with students. It is easy to love the nice ones and the beautiful ones; the real job starts with the difficult ones and recognizing that they are the ones that it is your duty and privilege to help. My naturalistic Darwinism — we are all part of the great web of life — reinforces this belief. Thank God (whatever that means!)

  4. James says:

    Of course, the moon does not exist in order to light the way home for drunken philosophers … but street light does. Purpose-like thinking is still valid. We just might need to find a correct purpose. The science can perfectly explain how street light works but would never tell why it is here. So, maybe both Emily Dickinson and Plato were seeing something that modern college philosophers are not?

    • Michael Ruse Michael Ruse says:

      Nonsense! No one is more critical of today’s philosophy than I — I think analytic philosophy done for itself is profoundly misleading and trivial. But I do think we have worked hard and to a great extent successfully on throwing light on causation and why final causation is meaningful and important. Read my book On Purpose, not because I wrote it but because I do draw so much on my fellow philosophers.

      That said, on behalf of drunken philosophers everywhere, let me say that the moon is a great help finding your way home!

  5. Wm. Burgess says:

    Here is another Poem from Emly Dickenson

    THE BRAIN is wider than the sky,
    For, put them side by side,
    The one the other will include
    With ease, and you beside.

    The brain is deeper than the sea,
    For, hold them, blue to blue,
    The one the other will absorb,
    As sponges, buckets do.

    The brain is just the weight of God,
    For, lift them, pound for pound,
    And they will differ, if they do,
    As syllable from sound.

    Plato said that a good philosopher, like a butcher with a carcass, divides nature at its joints. Nagarjuna would have answered that nature is nothing but joints. Dickenson’s worm and bird have brains as well as she, but their brains certainly divide nature along different joints than she did.

    Maybe there is little difference between the purpose of a thing and the brain which differentiates it into those lines of division which determine its boundaries as a separate ‘thing’ from the much larger system it operates in. I think Kant would say so.

    What determines how a brain divides nature into things other than what that brain values? What Dickenson’s brain valued caused her write this beautiful poem about itself. It seems almost a truism, to me, that the purpose of everything is to further the values which arise out of those wider, deeper, and most absorbent brains. Like Dickenson, I find it hard to imagine a more divine purpose than this.

    • Michael Ruse Michael Ruse says:

      Oh boy, I have to explain to people that I did not pay you to send in this question! This year I wrote On Purpose with Princeton UP — last year I wrote, Darwinism as Religion: What Literature tells Us about Evolution with Oxford UP. And what poem do I quote? The one you have just given us! I am showing how in reaction to the coming of Darwinism, people like Emily Dickinson were moving from the conventional Christian God to a more transcendentalist view, of God as a kind of life force behind everything — very much in the way of Spinoza and Deus Sive Natura (God or nature).

      So I am right with you William, right with you. Buy my book. Better still buy copies of my books for all of your relatives and friends, and make me a billionaire. Then I promise to come back to BQO and tell you all about how I manage the problem of purpose now that I am very, very rich.

  6. Monika says:

    Thank you, Professor.

    It’s seems to me that E. Mayr’s distinction between teleology and teleonomy may be helpful here. Organisms may evince purpose-like characteristics or teleonomy — a type of complexity that may even be emergent in some sense — but that doesn’t mean that we must make appeals to final causes in biological explanations (teleology). Nor, of course, does it mean that natural selection is inadequate as an explanation for how such complexity arose. But it may mean that biological phenomena are distinct from physical phenomena (though some physicists nowadays seem to think there may be emergent phenomena there as well).

    • Michael Ruse Michael Ruse says:

      Well, to drop a name, I knew Ernst Mayr (the distinguished evolutionist) very well and argued with him for thirty years — he was seventy when I first met him and thought our acquaintance would be short — he lived to be a hundred and was still writing books to the end! A real Mensch to use the language of his birth country. (Ernst came to America before Hitler came to power and was a man of the truest democratic convictions.) 

      He and I had endless fights over “teleology” versus “teleonomy,” meaning by the former some kind of final-cause thinking and by the latter something similar but entirely purged of any thoughts of gods or vital forces or anything like that — something completely natural in other words, though not materialist. (I never thought of Ernst as a materialist in any sense of the term.) I argued that “teleology” was a perfectly good word and we should use it to show its connection with a great tradition — after all, we use the word “atom” quite happily although we today have none of the science or metaphysics of the atomists of the Greek period.

      I used to joke: “You Ernst, a man with a good German gymnasium education, turning your back on philosophy — fie!” To which he would reply, “I’m an evolutionist, everything has its time and then we move on.”

      For me, teleology is thinking in terms of final causes in the sense that the worm existed in order to feed the bird — biologically I don’t think that is true but you know the meaning and the point. And Monika, you are right, natural selection can do the job totally and completely. In the human world — which again I think was produced by natural selection although I agree that our culture can take us beyond the immediately biologically valuable (can it indeed, as we look around today’s world) — my computer exists in order that I can write brilliant pieces for BQO and to write devastating responses to all the questions that it raises. I don’t invoke a God in doing this, nor do I need vital causes — nor did the bird feeding on the worm.

      So drop “teleonomy” — it is a nasty, ugly word anyway — enjoy the conversation that we are having now, and celebrate the memory of Ernst Mayr, a great scientist and a man who had such a wonderful zest for life.

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