Dialectic, Understanding, Peace
Plato founded his Academy around 380 B.C. in Athens at a site that was originally a park and public gymnasium outside the city. The Academy was legally recognized as a religious fraternity dedicated to the Muses. Students were expected to train with ten years of mathematics followed by five years of dialectic.
Aristotle is reported by Diogenes Laertius (c. A.D. 300) to have credited Zeno the Eleatic (f. c. 450 B.C.) with the invention of dialectic. It was considered a type of verbal polemic, but was transformed by Plato into the loftiest of philosophical methods. Plato described the Socratic method of questioning (elenchos) as dialectical. Scholars have claimed that Socrates sought definitions with his questioning, and that Plato substituted the Forms as an aim. But maybe Socrates wasn't seeking definitions. Maybe he wanted to show that the key concepts he asked about could not be defined. Knowledge would still be approached through finding out what is wrong with various proposed definitions. This would suggest a reading of Plato as holding that ultimate knowledge of the Forms is a sort of illumination reached after dialectic clears the way by eliminating various global theories.
Much of the Gorgias is devoted to the task of distinguishing dialectic from mere rhetoric. Rhetoric is denounced for not having any specific subject matter, and therefore of not being a real art. Worse, rhetoric is condemned for being indifferent to the truth of the claims it would teach one to defend. Plato puts this in the form of a proportion: "Sophistic is to legislation what beautification is to gymnastics, and rhetoric to justice what cookery is to medicine." (Gorgias, 465c) In each case, there is a contrast between what offers mere appearances and what really provides the object sought. Here, however, rhetoric is contrasted with justice instead of dialectic. Rhetoric attempts to give the appearance of justice, while justice is only achieved through dialectic; just as beautification gives the appearance of the strength that is really achieved through gymnastics. The contrast between dialectic and rhetoric is made explicit in the Phaedrus, where Plato warns that "it is because they are ignorant of dialectic that they are incapable of defining rhetoric." (Phaedrus, 269b)
The relation of justice to dialectic is critical to that of peace to understanding. Dialectic is the method used to achieve understanding. This understanding requires justice, for to engage in dialectic one must do justice to the various sides of an issue. That process clears the way for understanding. It is precisely that even handedness, fairness toward competing claimants, that is found in the just, and it is this justice upon which peace can be established. Thus we are led to peace through understanding.