Since Protagoras is dead, Socrates puts himself in the sophist's shoes and tries to do him the favor of defending his idea (166a-168c). Socrates concedes that if Protagoras were still alive, he would have more to say in his own defense, and that they are now essentially mistreating "his orphan child." Putting words in the dead sophist's mouth, Socrates declares that Protagoras asserts with his maxim that all things are in motion and whatever seems to be the case, is the case for the perceiver, whether the individual or the state.
At the end of his speech, Socrates admits to Theodorus that Protagoras would have done a far better job of defending his own ideas. Theodorus tells Socrates that he must be kidding, that he has come to the task with boyish vigor. Theodorus does not claim to be a disciple of Protagoras, but states that he was a friend. Socrates invites Theodorus to put up a more vigorous defense of Protagoras, as he does not want it suggested that he has used the child's timidity (of Theaetetus) to aid him in his argument against the doctrine of Protagoras (168d).
Socrates, not at all certain that he has not misrepresented Protagoras in making each man the measure of his own wisdom, presses Theodorus on the question of whether any follower of Protagoras (himself included) would contend that nobody thinks anyone else is wrong (170c). Theodorus proves to be helpless against Socrates' arguments. He agrees that Protagoras concedes that those who disagree with him are correct (171a). In making Protagoras a complete epistemological relativist, where every person's individual perceptions are his reality and his truth, both Socrates and Theodorus paint Protagoras as maintaining an absurd position.