To: Scott B.
From: Geoffrey Klempner
Subject: Aristotle's account of substantial change
Date: 14th October 2011 14:00

Dear Scott,

Thank you for your email of 3 October with your essay for the University of London BA module on Aristotle, in response to the question, 'Discuss Aristotle's explanation of change. Can it account for substantial change?'

This is for the most part a clear and thorough account of Aristotle's theory of change in terms of his notions of matter, form, potentiality and actuality.

Responding to the second part of the question, you include a discussion of Aristotle's account of coming into existence or going out of existence (substantial change), where in certain cases -- living creatures -- Aristotle is led to posit the idea of 'formless matter', a matter which we know on principle must remain the same, yet which cannot be identified in the process of change however closely we observe. You cite the examples of a vulture eating the carcass of a dead goat, and the coming to be of a human embryo from a sperm and an egg.

What is remarkable about this is that we have been led to this conclusion by logical steps starting from the axiom that in every change there is a component which remains the same throughout the change and another component which alters. You get credit for explaining this very clearly in your exposition.

I have a problem, as most contemporary philosophers would have, with the idea of 'formless matter'. It looks like a desperate resort to save a theory. Logically implied it may be, but surely Aristotle must have considered the possibility that there might be an alternative?

He did. And this is the really puzzling part. Aristotle was fully familiar with the theories of the atomists Leucippus and Democritus on the subject of change. When the vulture eats the goat, or when the sperm and egg combine, something happens on the microstructural level which we cannot observe because it is beyond the acuity of our sense organs.

On the atomist theory of change, all change is locomotion, an alteration in the arrangement of unchanging atoms. What appears as different qualities, such as water and ice, or the door painted blue and then red, or the quality of goat meat and the flesh of a living vulture, are merely effects on our sense organs of complex structures of atoms. This is, more or less, the story that science accepts today. Yet Aristotle rejected it outright. Why?

Interestingly, in current particle physics, there seems to be a point where we are unable to account for the changes observed in bubble chambers etc. except in Aristotelian terms. A particle of a certain kind displays a characteristic pattern as the result of a collision with a particle of another kind because that's just the kind of particle it is. That's all we can say. We are at the very bottom level, there is (or there appears) nowhere to go in the search for even deeper, more microscopic 'structures'.

It would be tendentious to attribute to Aristotle this degree of prescience, yet the stand which he took against atomism was a principled stand. I attended a seminar a few years ago when a philosopher (whose name I can't remember, unfortunately) gave a paper on Aristotle's text 'On Generation and Corruption' where he sought to explain Aristotle's position.

I found the explanation which he gave compelling. The fundamental premise of Aristotle's approach to these questions is that human beings have the power, through observation and reason, to account for the world around them. Remember that the very notion of a microscope or even a magnifying glass would have been unheard of. The speculations of atomists were unverifiable, and based on dubious metaphysical premisses. If the atomists were right, then as Democritus observed, human knowledge or the idea of science became something very doubtful indeed.

The alternative, Aristotelian explanation of change looks, from a modern perspective, almost tautological, like saying that 'opium makes us sleep because of its dormative property'. But he isn't looking for 'explanation' in the modern sense, that is to say, hypothetico-deductive explanation. He is seeking to resolve a logical problem, a logical challenge to the very idea of change. As you demonstrate in your essay, he succeeds in that task.

I do think the examiner expects you to say something more about the problem of substantial change. You give Aristotle's theory, but what you don't do (and I think what the examiner was looking for) is offer some sense of why this is such a challenge. What is the special problem here? Is it just that we are forced to posit 'formless matter'? Why is that so bad? Perhaps because this goes against Aristotle's own principles, that the account should remain at the level of what human beings can discover through unaided sense perception. This is the point, it could be argued, where Aristotle comes closest to doing the very thing he finds so objectionable in the atomist theory.

All the best,

Geoffrey