  The details of Plato’s argument, the fairness and the success of his strategy against Theaetetus and Protagoras are matters of some controversy.  A recent point of contention is whether Plato’s Protagoras is committed to a view of “relative truth” instead of flux, and how far Aristotle’s Protagoras is similar.  What is less controversial is that elements of Plato’s discussion re-surface in Aristotle’s Metaphysics IV.  Aristotle’s opponents are said to believe that knowledge is perception because they think that what they perceive is all that exists, and they are also said to be impressed by arguments from conflicting appearances. The thesis that knowledge is perception and an argument from conflicting appearances lead to Protagoras’s view in Plato’s Theaetetus. In Metaphysics IV 5, Aristotle agrees with Plato that Protagoras’s view and the suggestion that everything is “so and not so” (an expression echoed by Aristotle earlier at Metaph IV 4 1006a30–31) go hand in hand. The Protagoras of Plato’s Theaetetus and the PNC-opponent in Metaphysics IV 4 are said to be committed to the thesis that nothing is anything in itself, understood by Aristotle to mean that everything is accidental.