This paper is devoted to theParmenides’methodological preamble, in which Parmenides teaches how one is to lead a dialectical inquiry. The method presented there recalls the goddess’s advice, as presented by the historical Parmenides in his Poem, to think “the way of being and the way of non-being.” In Plato’sParmenides, these two ways are seen as manners of examining a hypothesis. I explain that the method is exhaustive insofar as it requires repeatedly asking what the consequences are if a thing does (...) exist, or does not. Lastly, I suggest that the method should be distinguished from other dialectical practices found in Plato’s work. (shrink)