Abstract
In discussing Socrates's argument for Plato's principle of change in the Phaedo, Syrianus asks, To what kind of opposites is Socrates referring? I offer a new answer to Syrianus's question. I start from David Sedley's view that the opposites in question are converse contraries, which behave as converses in comparative contexts. I show that the quantitative pairs that Socrates cites fit Sedley's view because they are implicit comparatives. Nonetheless, I argue that Socrates's evaluative pairs are better understood as asymmetrical opposites because the Phaedo and the Republic reveal that these pairs have independent, not relational, meanings. So my answer to Syrianus's question is that implicit comparatives and asymmetrical opposites are the kinds of opposites to which Socrates is referring.