Making Room for Matter

Socrates rejects material causes in the Phaedo, in sharp contrast to Aristotle, who gives them a fundamental role in his account of the natural world. Why do they disagree about this? It is sometimes suggested that Socrates rejects material causation because he requires causes to be rational or to be teleological. You might think, then, that Aristotle can have material causes because he does not have any such requirement. In this paper I argue for a different explanation. Plato and Aristotle ultimately disagree about material causation because of a difference in their causal frameworks: Socrates thinks that each change has just one cause, whereas Aristotle thinks each change has multiple causes. Because each change only has one cause in the Phaedo, a cause must provide an adequate explanation of a change on its own. Socrates rejects material causes because such causes, on their own, cannot adequately explain a change. Aristotle, on the other hand, thinks each change has four causes, which are all involved in the explanation of the change. This allows matter to be a cause for Aristotle, because it only needs to provide part, not all, of the explanation. The paper has three parts. First, I examine features common to Socrates and Aristotle’s causal theories in order to frame the discussion and argue that Plato and Socrates are not talking past each other. Second, I turn to why Socrates rejects material causes in the Phaedo, arguing that he rejects them because they violate the requirement that the same thing cannot cause opposites. Then I argue that Socrates is committed to this causal requirement because he is committed to one cause per change. In the third part of the paper I explain how Aristotle can have a material cause by having multiple causes. I claim that Aristotle draws attention to relevant anti-Platonic features of his causal account in a Physics passage that has not been fully appreciated