Philosophy has come to include, for us, a wide range of theoretical questions that typically look beyond what we can answer by experimental enquiries… - Catherine Rowett

Even if Melissus’s analysis of the concept of existence is faulty, his procedure is very interesting. He challenges the data of sense experience by appealing to conceptual truths, facts about what a certain predicate (here ‘true’) must entail. These facts seem to escape the need to appeal to sense experience. We check up what is true about being true by examining our notion of being true, not by checking any things in the external world. So the argument seems to find a way of challenging the value of sense experience without begging the question. Melissus casts doubt on the senses by privileging the logical grammar of the word ‘true’. But, we might ask, did we learn how to use the word ‘true’ without relying on the senses?

Plato’s metaphysics grew out of that of Parmenides, together with a strong feel for Heraclitus’s account of the physical world as a world of incessant change. His ethics were deeply inspired by Socrates, but his views on the soul also pick up on motifs that emerge in Pythagoras.

Plato not only permitted live philosophical enquiry to take place in the course of every reader’s every reading of the dialogue, by putting tempting and plausible views on trial, in a situation as near as possible to the open-minded exploratory give and take of dialectical debate with a real interlocutor. He also created a most fitting memorial to the real Socrates – the man himself, who lived and died for the idea that philosophy is best done in open-ended dialogue, and with your whole way of life at stake should you be refuted.