Timothy Clarke

The topic of this paper is Aristotle’s ‘proof by refutation’ of the Principle of Non-Contradiction (Metaphysics Γ 4, 1006a11–1007a20). I consider a worry which has often been raised in connection with this proof. The worry is that, faced with an opponent who is prepared to tolerate contradictions, the argument is dialectically powerless: it is incapable of getting them to abandon their position. In reply, I argue that the proof needs to be seen in its proper context, that is, as part of Aristotle’s response to an opponent who demands a demonstration of the principle. This allows us to clarify the purpose of the argument and answer the worry about its effectiveness.

In this book Timothy Clarke examines Aristotle's response to Eleatic monism, the theory of Parmenides of Elea and his followers that reality is 'one'. Clarke argues that Aristotle interprets the Eleatics as thoroughgoing monists, for whom the pluralistic, changing world of the senses is a mere illusion. Understood in this way, the Eleatic theory constitutes a radical challenge to the possibility of natural philosophy. Aristotle discusses the Eleatics in several works, including De Caelo, De Generatione et Corruptione, and the Metaphysics. But his most extensive treatment of their monism comes at the beginning of the Physics, where he criticizes them for overlooking the fact that 'being is said in many ways' – in other words, that there are many ways of being. Through a careful analysis of this and other criticisms, Clarke explains how Aristotle's engagement with the Eleatics prepares the ground for his own theory of the principles of nature. Aristotle is commonly thought to be an unreliable interpreter of his Presocratic predecessors; in contrast, this book argues that his critique can shed valuable light on the motivation of the Eleatic theory and its influence on the later philosophical tradition.