Monday, December 10, 2012
Aristotle's Four Causes
While reading Nagel’s proposal for a more complete, trans-physical account of nature, it occurs to me that the mind/body problem doesn’t seem to appear in Aristotle’s work at all. To be sure, Aristotle was a vehement anti-reductionist. This is especially evident in his remarks on Empedocles. The latter argued that the curvature of the spine is a result of the confinement of the fetus in the womb, which is the kind of thing you have to argue if you want to maximize the role of chance in all physical explanations. Aristotle rightly supposed that such features of anatomy have a species-cause.
By contrast, Aristotle saw no tension at all between materialist and mechanical explanations, on the one hand, and formal and teleological explanations on the other. Consider his famous account of the four causes. Here is the translation from my old Charlton edition of the first two books of the Physics.
 According to one way of speaking, that out of which as a constituent a thing comes to be is called a cause; for example, the bronze and the silver and their genera would be the cause respectively of a statue and a loving cup.  According to another, the form or model is a cause; this is the account of what the being would be, and its genera‑thus the cause of an octave is the ratio of two to one, and more generally number‑and the parts which come into the account.  Again, there is the primary source of change or the staying unchanged: for example, the man who has deliberated is a cause, the father is the cause of the child, and in general that which makes something of that which is made, and that which changes something of that which is changed.  And again a thing may be a cause as the end. That is what something is for, as health might be what a walk is for. On account of what does he walk? We answer ‘To keep fit’ and think that, in saying that, we have given the cause.
Cause here translates aitia, a word that philosophy borrowed from forensic language. It originally meant responsibility, as in who done it. In Aristotle’s work, it implies an answer to a certain kind of question.
Aristotle provides helpful examples in each case, but I will expand one of his examples to cover all four cases. Consider the development of a human being from conception to birth. How does one explain this process? One obvious answer is that the developing person comes to be out of certain kinds of material, which the scholarship refers to as material causation. Another answer is that the human being comes to be because the developing being is human in species. This is formal causation. A third answer is that Da knew Ma and got things rolling. That is efficient causation. Finally, the developing being develops toward a predetermined end, according to a program that was present at the very beginning. That is final causation.
I think that this is dead spot on. An organism, human or otherwise, comes to be because it comes to be out of certain kinds of material, just as a functioning machine is an arrangement of materials moving and changing in certain ways. I doubt that there is anything going on in a human body or mind that does not have a material substratum.
An organism comes to be from existing organisms of the same species. Cats give birth to cats and never to catfish. Aristotle recognized that the species form had to exist in two versions: the expressed organism (what we would call the phenotype) and the implicit form transmitted in the act of conception (the genotype). Aristotle thought that the latter was introduced by the father, whereas the mother supplied only the matter. We know better, but it doesn’t change the general scheme.
Efficient causation is what happens when an existing system is destabilized from outside. The father destabilizes the mother by introducing his semen. However, in the case of a developing organism, the force of efficient causation does not scatter like billiard balls. Instead, it gathers toward a predetermined end, guided by the species form. Final or teleological causation is an obvious fact of ontogeny.
Aristotle’s four causes make up a correct and comprehensive set of biological explanations. What is striking, from the viewpoint of contemporary philosophy, is that he didn’t see any conflict between material and efficient causation (which modern physical science has long wanted to rely on exclusively) and formal and final causation. He wasn’t the least bit worried about reducing the latter to the former nor did he desire it.
I suspect that one of the reasons for this is that Aristotle begins with biology. While his writing aims at a comprehensive account of nature, his preoccupied with animals. Modern science is beginning to come around to Aristotle’s way of thinking, through no fault of its own. The long dominion of physics, which began with the advent of modern science, is probably at an end. Biology is the most important of modern sciences just now, and that is good for science. It may be that living organisms have more to teach us than anything else in the visible Kosmos.