Title: 'Elimination, Contraposition and Explanation in Phiodemus' De Signis'
Abstract:
Philodemus' De Signis bears witness to debates held by certain Epicurean philosophers and an unnamed group of opponents over the status of two so-called 'methods of sign-inference'. In this paper, I discuss the method of elimination, which both the Epicureans and their opponents seem to take to provide an adequate account of the truth of certain conditionals and the validity of certain inferences. Focusing on a passage in which the Epicureans consider the ramifications of the law of contraposition on the methods of sign-inference, I show that the only way in which to rescue them from incoherence is to take them to be relying on an objective relation of causation, explanation or grounding when employing the method of elimination. But the account that emerges on this interpretation fails to validate certain inferences which the opponents appear to regard as valid, and is unlikely to satisfy some of their broader requirements for an adequate method of sign-inference. I conclude that although Philodemus presents the Epicureans and their opponents as both endorsing the method of elimination, in fact they have two quite different accounts in mind when they do so.
