Plato creates a seemingly invincible philosopher in The Republic. Socrates is able to refute all arguments presented before him with ease. The discussion on justice in Book I of The Republic is one such example. Socrates successfully refutes each different view of justice presented by Cephalus, Polemarchus, and Thrasymachus. Socrates has not given us a definitive definition of justice, nor has he refuted all views of justice, but as far as we are concerned in Book I, he is able to break down the arguments of his companions.

Cephalus is the first to give his opinion of justice as simply "speaking the truth and giving back what one takes." In even simpler terms, it is to do the right thing. (Republic 331) Socrates argues that to give a borrowed weapon back to a friend that has become insane is not justice but injustice. Cephalus concedes that his definition of...