Subtitle: how a modern physicist is liable to misunderstand Aristotle. This post was inspired by a very interesting post by Edward Feser here.
I have tried. What follows is my attempt to give full expression of my own ignorance. One of the conclusions I have drawn from my forays into Ancient and Medieval philosophy is that these are great thinkers.
Here is the standard illustration for Aristotle’s four causes. Consider a marble statue. The statue has four causes. The material cause is the marble, the material out of which the thing is made. The formal cause is the arrangement of the statue, its geometrical shape. The efficient cause is the “doer”, the sculptor, who arranges the material into the desired shape. The final cause of the statue is the purpose for which the sculptor has created the statue, e.g. to look beautiful in the garden.
Aristotle and Newton
Right, I think. My physicist training naturally has me try to cast my Newtonian (occasionally Einsteinian, sometimes quantum) view of the world in these categories. (This might be a bad idea, I think, given the discontinuity between Aristotle and Newton. Still, I’ll give it a go. Also, I’ll worry about relativity and quantum mechanics later, if at all.) So,
- Material cause – the particles of matter out of which physical things are made.
- Formal cause – the arrangement of those particles. Mathematically, a list of the position and velocity of each particle at some time
- Efficient cause – Newtonian forces, which move particles around.
- Final causes – an emergent, higher-level property of minds, who can make and execute plans.
(This is not the correct way to understand Aristotle, so stay tuned.) So far, so good, I think. The “Newtonian” material, formal and efficient causes give all the information one needs to solve Newton’s laws of motion. But now the confusion starts.
A lecturer giving an introduction to the history of science talks about Plato’s theory of forms as a realm of abstract but still “really” existing ideas. He later seems to suggest that the formal cause of a chalk circle drawn on the board is the idea of the circle in the mind of the lecturer. I ask, “For the circle on the board: is the formal cause the idea in the mind, or the idea of a circle floating out there somewhere in Plato’s realm?”. “Uh … have you been reading the Scholastics?”, he replies. “Nope”. I can’t remember the rest of his answer – it was rather vague. I’ve had a chance to ask a few other philosophers about formal causes since, and their reply usually starts with a grimace.
Enter Feser
So it was that I came to Edward Feser’s Aquinas (A Beginner’s Guide). His exposition is admirably clear, and it is obvious that I must change my understanding of the four causes. In particular, final causes are more than just intentions of minds. There are natural final causes. When a match is struck and fire is created, the efficient cause of the fire is the match. At the same time, the final cause of the match is the fire. The properties of the match “point to” or “are directed at” the creation of fire. Fire is what matches do. The match isn’t just a generic efficient cause that could cause any old thing but just happens to cause fire every time. Its ability to do something is controlled by fire as its final cause. I picture this as the efficient cause being the engine, and the final cause as the steering wheel. The efficient cause does the causing, and the final cause directs the efficient cause towards the production of its effect.
The shocking thing about this, as Feser points out, is that the scientific revolution, despite its PR, didn’t get rid of final causes. Final causes are how Aristotelian metaphysics explains the orderliness of nature. The fact that things keep doing the same kind of things – trees grow, the sun shines, fire burns, dropped stones fall – is because the efficient causes in the world are conjoined (is that the right word?) to final causes, ensuring that they produce consistent effects. The “laws of nature”, to use an slight anachronism, are more about final causes than efficient ones. But that is a topic for another day.
Despite Feser’s clarity, formal causes now get even more confusing. Feser argues that things can be imperfect instantiations of their form. Their form isn’t just how their parts are arranged. It is, in some sense, how they should be arranged, what their essential arrangement is. For example, when a person loses a leg, they don’t take the form of a one-legged person. Their true, two-legged human nature is still there in the person, but it is instantiated imperfectly.
Note that Aristotle differs from Plato in locating the form of a thing in the thing itself, not in some ideal external realm of forms. It isn’t just that the person fails to replicate the ideal of a two-legged Platonic person “up there”. The one-legged person still has the form of a two-legged human. Two-legged-ness is still in there, somewhere. (more…)
Letters to Nature 