As the argument grows more complex, so do the methods of argument in the dialogue grow more intricate. In arguing things apparently far removed from the point of the argument (justice, the just man), Socrates is attempting to elucidate the point of the argument by arguing similar instances; that is, he is arguing analogies. Socrates descries a single like aspect in the series of analogies he argues: a horse, a dog, a horseman, a musician — all may be said individually to possess a distinct essence or virtue or quality. Thus if we do injury to a given thing's essence, we may be said to do injury to the virtue of a given thing or being. We have agreed that the virtue of a human being is justice, or his sense of justice. It follows, then, that if we do evil to another human being, we are perpetuating an injustice; we cannot achieve justice by committing unjust acts.
As we have said, Socrates is citing analogies in his argument in order to clarify the point of the debate; analogies are permitted in argument if they do in fact clarify the point of the debate. Analogies cannot be used as proof; and we must always determine the worth of a given analogy by demonstrating its similarities to the point of a given argument. If the analogy is shown to be similar in significant aspects to the point of the argument, it is said to be a valid analogy. If the analogy is determined to be entirely dissimilar, it is a false analogy and may be dismissed from the argument.
