The Visitor claims to be amazed at the sophists’ ability to make young people believe that they know everything about everything. They are good at feigning knowledge, but what they possess cannot be a true understanding, but only plausible beliefs. In fact, the sophists must promote false beliefs. Yet the claim that there are false beliefs is problematic in the Eleatic tradition, because according to Parmenides you can’t even entertain false beliefs. The Visitor quotes two lines from Parmenides’ poem:
Never shall this prevail, that things that are-not are.
But you, withhold your thought from this way of inquiry.[4]
Parmenides has already stated that you could not know what-is-not, or even express it.[5] The Visitor explains that if Parmenides is right, you can’t say, think, or know what-is-not because it is-not.[6] How can you say something about nothing?
This indeed had been a standing to problem for philosophy since Parmenides published his poem. How can we talk about or even express what-is-not insofar as it is not? The prohibition against not-being seems to be so strong as to preclude us from even using a ‘not’ to talk about what-is. Parmenides certainly uses negations in his poem, but his argument makes us worry about the meaningfulness of doing so. If we cannot say, for instance, Socrates is not Plato, or white is not black, it appears that we cannot distinguish one person or thing or property from another. If not, then differences cannot exist, everything will be one. That may be Parmenides’ point: to establish an extreme monism. He does not, however, ever say that everything is one, nor does he talk about the One in his extant writings, even if Plato and most other ancient commentators attribute the phrase to him.[7] But how are we to justify talking about what-is-not, given the very fundamental challenge that Parmenides raises? And how, moreover, are we to defend talking about what-is-not without violating Parmenides prohibition against talking about it?
The Visitor realizes that it will not do to finesse the Eleatic challenge. We must confront it, and indeed be willing to contradict Parmenides. “We will have to defend ourselves,” he says, “by putting the theory of Father Parmenides to the test and proving by force that what-is-not is in some way, and also that what-is in some way is not.”[8]
[4] Parmenides fr. 7. 1-2, quoted at Sophist 237a.
[5] Parmenides fr. 2.
[6] Plato Sophist 237b-238c.
[7] Parmenides fr. 8. 6 uses hen ‘one’ only as a predicate adjective, not as a substantive or definite description. For frequent talk about the One, see Plato’s Parmenides.
[8] Plato Sophist 241d.