DISCLAIMER: This discussion is not intended to be a debate between Thomism and Materialism. If you are a materialist, please give the hypothetical Thomist answer or refrain from participating. I am trying to understand a particular philosophy, hence the question. I am already familiar with materialism, atomism, and the fundamentals of neo-Darwninism.
How do we reconcile the idea of form with the evolutionary concept of common descent?
It seems to me that a form is a fixed thing that defines its “it-ness” and matter will arrange itself to match the form, the form guides growth. Fair enough, neo-darwinism does fail in explaining everything through “random” mutation because many mutations are not in fact random (see the immune system and mutation on v-regions of lymphocytes for example). So, on this count, Thomistic form is compatible with modern science, and could be seen as a competitor or compliment to neo-lamarckianism and some evo-devo explanations of development.
However, unlike the strong form of neo-darwinism (ALL change is the result of the random mutation of germline genes), common descent is a provable fact. If species are always in flux, then how does this square with the idea of fixed forms?
AFAIK, form only makes sense if the world were to contain fixed species.
I would guess the answer is out there, since the common descent was actually in-vogue, if I understand correctly, in St. Thomas’s day.
Hi. Here’s a rather long quote in response (ignore the citation references):
Another scientific objection to natural law theory, and perhaps a more consequential one, arises with the consideration of Darwinian concepts of evolution by means of natural selection. After all, the essence of natural law theory is that everything comes in a natural type, a genus. What happens to natural law if those natural types are shown to be fluid and ever-changing through the processes of evolution? In addition to the challenge to human beings as a “natural type,” perhaps evolutionary theory poses another challenge: that human beings are “just another animal,” and therefore human rationality, though it exists, does not carry the metaphysical significance Aquinas and Aristotle think it does. As a contemporary Thomist writes:
“One of the important presuppositions of classical natural law theory is the presence of such a thing as human nature. But modern biology has raised all sorts of interesting questions for natural law theory, particularly associated with the theory of evolution. Does the theory of evolution, for instance, simply negate all natural law theory whatsoever, as well as natural rights claims, by reducing us to just one more animal species?”
If one is dealing with a strictly reductive and materialistic evolutionary theory, such a theory does in fact reduce humanity to “just one more animal species,” by eliminating the metaphysical significance of human rationality. (This is not meant to imply that Homo sapiens is not an animal species.) However, arguments against reductive materialism have already been offered earlier in this chapter (Section 1[2]) and will be further discussed in Chapter 3. On the other hand, even if the evolutionary theory under consideration is not necessarily materialistic, the idea of an unstable, still-developing humanity seems contrary to the idea of a stable, developed human form. In Thomistic terminology, the changes in humanity itself due to evolution would not seem to be “incidental” changes, but rather “substantial.” One theologian has even argued that Thomistic natural law theory can no longer be a “cohesive social force,” since evolutionary theory requires that “human nature no longer be depicted in terms of a basic human essence or purpose.”
However, evolutionary theory does not in fact invalidate the two-fold basis of natural law theory: that humans today are of a specific and unique kind, and that this specific and unique human nature points toward a natural human telos. As Koterski continues:
“Even if evolutionary theory proves true, this does nothing to attack natural law theory, insofar as natural law theory is based on the difference of kind and an analysis of what that difference in kind (i.e., our rationality, our ability to make free choices) includes within the scope of its rationality. Even if, for instance, we should find that the dolphins or the chimpanzees are our kissing cousins in ways that we have never imagined . . . all it would do is move the line of what species are protected by rights, precisely because of their rationality. . . . It would simply move the line of what it is that deserves moral protection, rather than erase the line. It would not do anything to erase the fact that there is a difference in kind; it would simply give us other creatures who are different in kind and also deserve such moral protection.”
The activities of thinking and choosing make humans distinctive creatures; not only that, these activities make humans distinctively moral creatures. This would remain true even if species identification ultimately collapses even further than it already has, for a biological collapsing of categories would not necessarily entail an ontological collapsing of categories. It would be possible to defend natural law moral theory “even if the scientific evidence eventually points to the existence of no more than two distinct ontological species—rational animals and everything else.”
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