m. And it was in this way that Gorgias made use
of the dialectic of Zeno. Since all existence is self-contradictory,
it follows that nothing exists. He also made use of the famous
argument of Parmenides regarding the origin of being. If anything is,
said Gorgias, it must have had a beginning. Its being must have arisen
either from being, or from not-being. If it arose from being, there is
no beginning. If it arose from not-being, this is impossible, since
something cannot arise out of nothing. Therefore nothing exists.

The second proposition of Gorgias, that if anything exists it cannot
be known, is part and parcel of the whole Sophistic tendency of
thought, which identifies knowledge {118} with sense-perception, and
ignores the rational element. Since sense-impressions differ in
different people, and even in the same person, the object as it is in
itself cannot be known. The third proposition follows from the same
identification of knowledge with sensation, since sensation is what
cannot be communicated.

The later Sophists went much further than Protagoras and Gorgias. It
was their work to apply the teaching of Protagoras to the spheres of
politics and morals. If there is no objective truth, and if what seems
true to each individual is for him the truth, so also, there can be no
objective moral code, and what seems right to each man is right for
him. If we are to have anything worth calling morality, it is clear
that it must be a law for all, and not merely a law for some. It must
be valid for, and binding upon, all men. It must, therefore, be
founded upon that which is universal in man, that is to say, his
reason. To found it upon sense-impressions and feelings is to found it
upon shifting quicksands. My feelings and sensations are binding upon
no man but myself, and therefore a universally valid law cannot be
founded upon them. Yet the Sophists identified morality with the
feelings of the individual. Whatever I think right is right for me.
Whatever you think right is right for you. Whatever each man, in his
irrational self-will, chooses to do, that is, for him, legitimate.
These conclusions were drawn by Polus, Thrasymachus, and Critias.

Now if there is, in this way, no such thing as objective right, it
follows that the laws of the State can be founded upon nothing except
force, custom, and convention. We often speak of just laws, and good
laws. But to speak in that way involves the existence of an objective
{1