|Comments on the Republic
4. The three parts of the soul
|3. The three
parts of the soul
Immediately after the discussion of the virtues of the state Plato takes up a discussion of the the three parts of the soul (436a-437d). Actually, the discussion is spread out in different sections of the Republic. I will pull them together at this point. The three parts of man's soul, for Plato, are reason, spiritedness, and the appetites. We all have an intuitive sense of the notions of reason and appetites, but what does Plato mean by "spiritedness" (or, in Grube's translation, the "spirited part")? He seems to mean the competitive, ambitious, and aggressive aspect of man's nature (see 411b-c, and 439e-440e). Plato's theory of the three parts of the soul of man should not be interpreted, I believe, as referring to three different areas in man.
Rather, the sense of "parts" here is closer to aspects, or activities. Plato wishes to say that man's soul is one, but this one soul displays three different kinds of activities. Plato also proposes that there is a correlation between the parts of the soul and the classes and virtues. (He does not say this explicitly in ony one place, but he hints at it in many places in the Republic). Thus we now have a threefold correlation.
Finally, what reason does Plato offer for the position that there are three parts of the soul? He appeals to the principle of contradiction (sometimes also called the principle of non-contradiction--it is the same principle): A thing cannot have a characteristic and not have a characteristic at the same time and in the same respect. Thus something cannot be hot and cold at the same time (one part of a thing may be hot and another part cold at the same time, but not the same part), something cannot be undergoing a chemical reaction and not undergoing a reaction at the same time, and so on. For Plato's version of the principle, see 436b, and then see how he applies it to the different activities of the soul and from this arrives at the three parts.