  Plato goes on to argue that Protagoras is committed to the view that nothing is anything in itself (otherwise one might be wrong about how it really is) and to a “secret” Heraclitean doctrine of flux. In order to accommodate more and more conflicting appearances, and to avoid violating PNC, more and more flux is needed, until we reach a radical version of Heraclitus’s doctrine according to which everything is “so and not so” (Tht 183), with accompanying difficulties for ordinary language. The extended argument also contains a mini-argument, a “self-refutation”, where Plato draws the “exquisite” conclusion that Protagoras refutes himself if he agrees that other people disagree with his own view (Tht 171A-D). If they are right, then he must be wrong!