Aristotle's Argument Against Evolution

If evolution were a question of purely scientific character, one would not expect cogent philosophical arguments against evolution that transcend time, place, and the state of scientific progress.

1. Philosophy and Evolution

The claim that the theory of evolution is settled science has never sat well with me. My reservation is not primarily that the scientific support of evolution can be contested, though it can. Instead, my reservation has been that the question of evolution is not purely, or even primarily, a scientific one.

Some hallmarks of a scientific question are its being resolvable by experiment and observation, its definite and technical nature, and its amoral and non-metaphysical character. But when scientific prose begins to wax metaphysical, you know that science has been left behind, as when Neil deGrasse Tyson or Carl Sagan contemplate with wonder the vastness of the universe. When scientists treat a traditionally philosophical question and write a New York Times bestseller, you know that science has been left behind, as Sam Harris has done with free will or others with the nature of consciousness.

The question of evolution oversteps the boundaries of science in these same ways. It is the linchpin of atheistic metaphysics, to quote Richard Dawkins: “Darwin made it possible to be an intellectually fulfilled atheist.” It serves as the foundation of many a philosophical theory, for example, the entire corpus of Daniel Dennett. Instead of being of a limited, dry, and technical character, it purports to determine whether human beings were made in the image of God or are rather merely “apes with ego trips.” And what is more, it is impossible to resolve entirely by experiment and observation, both in that it is relegated to the distant past, and in that macro-evolution has yet to be observed in the present.¹

In my Wednesday post, I came down rather hard on the doctrine of a certain Christian sub-culture, of six, twenty-four-hour day creation. My chief objection was its attempt to settle matters of origins from the Bible alone, as opposed to allowing for other sources of knowledge. In this post, I want to do something more positive, and in particular, to show how another source of knowledge provides evidence on the question of origins. That source is not science, but philosophy.

In my own intellectual history, it was as I was detecting the other-than-scientific character of the question of evolution that I also became aware that several great philosophers in the history of thought have commented on the question of evolution on philosophical grounds alone. Now, if evolution were a question of purely scientific character, one would expect that a philosopher would not have much to go on. Or one would expect that a philosopher’s answer would have been superseded by science, in the way that some ancient thinker’s beliefs about physics were surpassed by the observations of Renaissance and Enlightenment scientists. Instead, one observes in these philosophers cogent philosophical arguments that transcend time, place, and state of scientific progress.

Two such philosophers are of note: Aristotle and Hegel. Hegel was in many ways a modern Aristotelian, attempting to resuscitate the teachings of Aristotle in the aftermath of the Enlightenment. Hence, Aristotle is the source of this tradition of thought, and so, it is to him that we turn.

2. Aristotle and Ancient Materialism

In Aristotle, we find a philosophical argument against evolution that is as powerful today as when it was written, perhaps more powerful in that it has stood the test of time and reveals modern evolutionary theory to be but the latest version of an ancient materialist metaphysics. In brief, Aristotle’s argument is that chance and necessity are insufficient explanations of the organization of biological life. Biological life requires a unique explanation, nature, that shares with intelligence a teleological, or purposive character.

The background of Aristotle’s argument is the history of pre-Socratic physical thought. The earliest philosophers of Greece - Thales, Heraclitus, Empedocles, Democritus - focused on offering quasi-scientific explanations of the physical universe. They were as much the progenitors of science as of philosophy. Philosophy as we know it, being concerned with a wider array of questions, especially those more pertinent to humanity, like questions of knowledge and ethics, arose with Socrates, who turned attention from the physical world to the human world, with rather dire social, legal, and physical consequences for himself.

The predecessors of Socrates were largely materialists. They sought to explain the existence of the material world in terms of material causes. Their theories read much like early attempts at a very short table of elements: water, air, fire, etc. (Not to mention love, strife, etc.) It was the coming of Socrates, followed by Plato and Aristotle, that gave rise to a worldview that gave more prominence to mind than matter. (Hence, today’s materialism is really a return to the most primitive kind of philosophy.)

Unsurprisingly, among these pre-Socratic thinkers, there arose theories of living things that depended on chance and necessity and material causes rather than purpose or intelligence. A prominent such theory was that of Empedocles, which Aristotle himself cites. Empedocles proposed that in the primordial state, different organs and parts of animals were separate and mixed up but began to combine randomly in different configurations. Those configurations which were most fitting survived, while others perished.

Here is Empedocles:

From it [the earth] blossomed many faces without necks,

Naked arms wandered about, bereft of shoulders,

And eyes roamed about alone, deprived of brows.

Many grew double of face and double of chest,

Races of man-prowed cattle, while others sprang up inversely,

Creatures of cattle-headed men, mixed here from men,

There creatures of women fitted with shadowy genitals.²

And here is Aristotle’s summary:

“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 organized spontaneously in a fitting way; whereas those which grew otherwise perished and continue to perish, as Empedocles says his ‘man-faced ox-progeny’ did.” (Physics, II. 8 198b 29-33)

Proponents of evolution will argue that, while this theory displays the idea of survival of the fittest or natural selection in a very primitive way, it lacks the sophistication of evolutionary theory with its gradualism and its idea of environmental constraints and of random mutation. However, this is where philosophy is important, because the philosopher observes that, no matter how sophisticated one makes the theory of random mutation and natural selection, it is the same theory.

Aristotle puts the point by identifying Empedocles’ theory as reducing down to the explanation of living or natural things in terms of chance and necessity. In other words, whether the chance takes the form of an original array of detached body parts or random genetic mutations, and whether the necessity is in terms of ancient materialist understanding or modern physical and chemical theory, the idea is the same: Living things, the parts of which appear to be united for a purpose, can ultimately be explained without reference to purpose but only in terms of chance and necessity.

Modern opponents of evolution, or at least of neo-Darwinism with its constraint of randomness, take pains to rebut each particular theory of evolution or abiogenesis with scientific detail. Aristotle is unaware of each of these particular theories which postdate him significantly. But that is no matter, because Aristotle’s philosophical arguments are of a general character: They look at what is common to all explanations in terms of merely chance and necessity and point out their insufficiency.

3. Aristotle’s Argument

The argument comes in the second book of Aristotle’s Physics. In that book, he discusses the different causes that play a role in nature. In particular, he focuses on the causes chance, necessity, nature, and intelligence. (Note: These are not Aristotle’s famous “four causes,” which are the formal, material, final, and efficient causes. How these interrelate is another question.) Aristotle seeks to determine whether each of these should count as a cause, what its characteristics are, and by how it may be identified.

Importantly, he determines that chance is what he calls an incidental cause, as opposed to a proper cause. For instance, if two people run into each other in the marketplace who were not intending to meet, their meeting is due to chance. Of course, the reason that each person is in the marketplace is not simply chance. One is there to buy some bread, the other some vegetables.

Chance is also to be identified as a cause only of things that happen relatively infrequently. If something happens always, we rather attribute it to necessity. If something happens almost always, or for the most part, we also cannot attribute it to chance but, as he will argue, to nature.

Things that happen always we attribute to necessity as, for example, the sun rising daily.

Things that happen, as Aristotle says, “always, or for the most part,” we attribute not to chance, nor to necessity, but to nature. For instance, if crape myrtles blossom in June, we attribute it to nature, even if some of them fail to do so.

Now with that background, here is Aristotle. Referring to the above arguments that living things can arise from chance and necessity:

“Such are the arguments (and others of the kind) which may cause difficulty on this point. Yet it is impossible that this should be the true view. For teeth and all other natural things either invariably or normally come about in a given way; but of not one of the results of chance or spontaneity is this true. We do not ascribe to chance or mere coincidence the frequency of rain in winter, but frequent rain in summer we do; nor heat in the dog-days, but only if we have it in winter. If then, it is agreed that things are either the result of coincidence or for an end, and these cannot be the result of coincidence or spontaneity, it follows that they must be for an end; and that such things are all due to nature even the champions of the theory which is before us would agree. Therefore action for an end is present in things which come to be and are by nature.”

The argument is, like all of Aristotle’s arguments, dense. Put another way, we have already determined the means of identifying roughly what is due to chance, what necessity, and what nature. Chance can explain what happens infrequently and by coincidence; necessity can explain what happens always and invariably; and nature explains what happens always or for the most part. Taking any of the aspects of a living thing, we find that they happen not infrequently. Humans having 32 teeth, for example, happens not infrequently. On the other hand, it does not happen always, and hence by necessity. Rather, it happens “for the most part” and “normally.” Thus, it is due to nature, rather than to chance or necessity.

But Aristotle’s further claim is that it happens “for an end.” What does he mean? Aristotle does not mean that to refer to a further end, external to the organism, like a purpose God had in mind in giving human beings 32 teeth. Rather, Aristotle famously holds that living things exhibit intrinsic teleology. Most basically, human beings have 32 teeth because having 32 teeth is an end or purpose of their nature. In modern terms, we could point out that having 32 teeth is part of the human body-plan, encoded in human DNA. It is, therefore, no coincidence when a new human pops out with the tendency to grow - count ‘em - thirty-two teeth.

Now the evolutionist may reply, “I’m not saying that it’s a mere coincidence that each human being has the same body plan. I’m saying that the human body-plan along with all others arose through a complex process of chance and necessity, constrained by the needs of survival. I’m not saying the human beings aren’t well-fitted to survive and reproduce (including by having 32 teeth), but that this fitness arose without intention or purpose.”

The evolutionary argument, put another way, is that the appearance of design, evidenced by the fitness of things for survival, can be explained in terms of chance and necessity. On this view, if there is such a thing as nature and at least apparent purpose, these causes are posterior to the more fundamental and prior causes of chance and necessity.

However, Aristotle has already shown that chance in particular depends on end-oriented action, whether intelligent action, like that of the two men meeting in the marketplace, or natural activity. Chance, coincidence, and spontaneity occur as incidental effects of the interactions between things that are caused by nature, intelligent action, or even, necessity. Aristotle had put it this way, in an earlier paragraph:

Spontaneity and chance are causes of effects which, though they might result from intelligence or nature, have in fact been caused by something incidentally. Now since nothing which is incidental is prior to what is per se, it is clear that no incidental cause can be prior to a cause per se. Spontaneity and chance, therefore, are posterior to intelligence and nature. Hence, however true it may be that the heavens are due to spontaneity, it will still be true that intelligence and nature will be prior causes of this All and of many things in it besides.

In other words, it is not chance that is prior to nature or intelligence, but nature and intelligence (and necessity) that are prior to chance.

Let me give an example of merely apparent purposiveness that Aristotle would accept. Let’s imagine that a Native American is searching for an arrowhead. By a brook, he finds many stones that could be shaped into an arrowhead, but then one that already has an almost perfect shape, as if it were purposely shaped to be an arrowhead (though it was not).

Notice: This example of merely apparent design has the markings of a chance-based event. It does not happen always or for the most part, but rather infrequently. It depends on other things that are occurring by necessity and nature, the shaping of stones by water.

What this means is that the ordering of the organs of a living thing could only be attributed to chance and necessity alone if it was as infrequent as this. Imagine Empedocles’ primordial zoo of animal parts. Without inquiring into the great complexity and orderedness of the parts and organs of animals, but just taking them for granted, very rarely some parts would combine in a way that resembles a functioning organism. But most would not. If we encountered a world like that, we could indeed say that those rare apparent organisms were due to chance and necessity alone.

However, our world is not at all like the world Empedocles imagined. Instead, we encounter a world replete with bodies that have a highly complex but ordered and functional arrangement of their parts. What is more, each of these bodies is self-reproducing, by a system that itself is highly complex but ordered and functional. Even more, these bodies exhibit engineering down to the molecular level, with parts so exquisitely ordered to a purpose that they easily surpass the best of engineering done by humans.

The details are best left for a post dealing with the evidence of intelligent design, but I’ll leave you with this example from Michael Behe’s Darwin Devolves:

These are the leg gears of the planthopper. The planthopper surpasses the grasshopper in being able to jump to heights hundreds of times its body length. In order to facilitate this, its legs must move “in synchrony very quickly, more quickly than it takes for a full nerve impulse to reach the legs.”

Behe continues:

“If one leg is triggered before the other, the insect would lose power and tumble erratically. With the gear teeth engaged and the gears spinning at an astonishing fifty thousand teeth per second, as one leg starts to move, the gear rotation starts the other leg moving as well, and the bug gets maximum power and coordination for its efforts.”

While much more detail can and must be filled in, this is the core of Aristotle’s argument against the explanation of nature in terms of chance and necessity, the modern version of which is neo-Darwinian evolution. As scientists propose further versions of evolution, what they always bump up against is the limit, identifiable by philosophy alone, of chance and necessity to explain what is ordered and purposeful.

Once again, Aristotle sums it up well:

“Spontaneity and chance, therefore, are posterior to intelligence and nature. Hence, however true it may be that the heavens are due to spontaneity, it will still be true that intelligence and nature will be prior causes of this All and of many things in it besides.”

1. The boundary between micro-evolution and macro-evolution appears to lie at the biological level of “family,” according to Michael Behe. Speciation, the natural equivalent of what dog-breeding has done for canines, has indeed been observed in nature. “Chapter 6: The Family Line,” in Michael Behe, Darwin Devolves: The New Science about DNA that Challenges Evolution. Pp. 141-170.

2. https://plato.stanford.edu/entries/empedocles/#Zoog