In Catholic circles today, it is common to accept the theory of Evolution uncritically. It is assumed that ancient or medieval wise men did not ever consider such a theory or that they lacked evidence to propose it. But this is not the case. They had the same evidence modern men have and they were able to observe it, speculating that form in nature is a result of natural selection.
Indeed, Aristotle tells us that the theory of Evolution, and its more developed criteria via “natural selection” was already known and posited even before his time. Obviously they did not use these technical terms, which are modern, but the signification of those terms is the same as the ideas signified in the ancient world. Natural selection teaches that when a certain trait of an animal develops by chance, if it is beneficial to the animal for survival it will endure in the species. Alternatively, if a certain trait developed that is not beneficial it is likely not to be passed on to the successive generations because such individuals would be less likely to reproduce. Therefore, the resulting physical form of animals is the consequence of the preservation of beneficial traits and the elimination of undesirable ones.
In his Physics, Aristotle considers this very argument, which is more ancient than his day since it had been posited by Empedocles a century before him.
“What then hinders but that the parts in nature may thus subsist? For instance that the teeth should arise from necessity; those in front, indeed, sharp, and adapted to divide; but the grinders broad, and adapted to breaking the food in pieces: for it may be said that they were not made for the sake of this, but that it so happened: and in like manner with respect to the other parts of the body, to which a subsistence for the sake of something appears to belong. Where, therefore, all things happened as if they were made for the sake of something, these were preserved, being aptly composed from chance; but such things as were not thus made, these were lost and still perish, according to what Empedocles says concerning the bull species with human heads. This, therefore, and a similar reason, if there be any such, may lead someone to doubt on this subject.1
What he means that this may lead someone to doubt on this subject is that men may doubt that things in nature subsist for the sake of a certain end. Men might be tempted to assume that the things in nature which appear to be suitably adapted for a certain purpose are not in fact purposeful, but rather come about by chance. And these chance happenings in animal forms are preserved, whereas the chance happenings in nature which do not contribute to some end perish. This is the modern theory of natural selection. He clearly precludes this as possible:
It is, however, impossible that these things should subsist after this manner: for these, and everything which is produced by nature, are either always, or for the most part thus produced; but this is not the case with anything which is produced from fortune and chance.”2
The foundation for Aristotle’s rejection of the possibility of forms being the result of natural selection is that these things in nature (things which are produced for a certain end) are generated every time, or nearly every time. Things in nature which are produced by chance do not have this same quality. This is what he means that nature has a final cause, which he has already spent many chapters proving. Final cause might be called “teleology” today. St. Thomas Aquinas comments on this part of the Physics:
“Hence it seems that there is nothing to prevent this from being true also in regard to animals, which seem to be disposed for the sake of some end. For example, one might say that because of the necessity of matter some teeth, i.e., the front teeth, happen to be sharp and suitable for cutting food, and the molars happen to be broad and useful for grinding food. Nevertheless, nature did not make the teeth such and so for the sake of these utilities. Rather after teeth have been made by nature in such a way as they develop from the necessity of matter, it is accidental that they acquired such a form. And once this form exists, this utility follows. And the same thing can be said of all other parts which seem to have some determinate form for the sake of some end.”3
Ancient men in general seemed to agree that there appears to be a final cause, or end, in nature. So, those who thought that form came about by chance posited the theory of natural selection, before it was called such. Aquinas again explains this theory and rejects it as possible in his commentary on the Physics:
…they say that from the beginning of the formation of the world the four elements were joined in the constitution of natural things, and thus the many and varied dispositions of natural things were produced. And in all these things only that which happened to be suitable for some utility, as if it were made for that utility, was preserved. For such things had a disposition which made them suitable for being preserved, not because of some agent intending an end, but because of that which is per se vain, i.e., by chance. On the other hand, whatever did not have such a disposition was destroyed, and is destroyed daily. Thus Empedocles said that in the beginning things which were part ox and part man were generated.
…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…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.”4
Therefore, we see proof that the theory of Evolution by natural selection was present at least in the 5th century BC in the work of Empedocles. It was rejected in Aristotle and Aquinas on the grounds that the final cause in nature is the origin of form and is the work of an intellect; such form cannot be attributed to chance or fortune in nature.
Some Catholics unreasonably suggest that God used chance, and therefore evolution by natural selection, to bring about the forms of animals in nature. But this is unreasonable because chance in nature is proven by Aristotle to not bring about teleological form, that is, things which are produced for a certain end do not come about by chance. Since we know that God does not act unreasonably but rather in accord with reason, which is the basis for our ability to say that nature is intelligible, it appears that evolution by natural selection is not possible.
- Aristotle, Physics, Book II, Chapter 8. English translation by Thomas Taylor. ↩︎
- Ibid. ↩︎
- Aquinas, Commentary on Physics, Lecture 12. Translation by Blackwell, Spath and Thirlkel, Yale University Press, 1963. ↩︎
- Ibid. ↩︎
