In this fine study, Hendrik Lorenz revisits Plato's argument for a tripartite soul in Republic IV. He proposes an interpretation that seeks to explain how the Principle of Opposites ("the same thing will not be willing to do or undergo opposites in the same respect in relation to the same thing, and at the same time," Rep. 436b8–9) when supplemented by examples of motivational conflict, can show that reason, spirit, and appetite are basic, non-composite parts of the human soul.
The discussion of parts of soul is merely a prelude to Lorenz's discussion of non-rational cognition in Plato and Aristotle in the final two parts of the book. Even readers who wish to quibble with Lorenz's analysis of psychic parts are likely to find his detailed and textually astute analysis of non-rational cognition intrinsically rewarding. Here is how the themes connect: Lorenz holds that in order to prevent the principle of opposites from running amok, yielding a number of psychic subparts, Plato must deny the ability to reason, or even to understand the deliverances of reason, to the non-rational parts of the soul. How, then, can Plato account for the fact that non-rational parts are capable of giving rise to fully [End Page 477] formed motivating conditions? Many critics have thought that Plato attributes a capacity for means-ends reasoning to appetite. He calls it the "money-loving" part, because we most of all satisfy the desires for food, drink, and sex through money (Rep. 580d10–81a 1 ). But if appetite can reason about means to ends, then it seems that appetite will be vulnerable to internal subdivision. The oligarchic person could, for instance, be averse to making large-scale public donations, but simultaneously desire it as a means to the achievement of a goal, say cultivating his reputation.
Critics have responded to this puzzle by narrowing down the part-revealing conflicts, attributing to Plato the view that only conflicts between first-order and second-order, evaluative desires reveal parts. Lorenz rightly rejects this view, insisting instead that the appetitive part is incapable of using reason. He defends what he calls the "simple picture." The simple picture makes the simultaneous occurrence of a desire and an aversion towards one and the same object sufficient to expose a partitioning of the soul. Means-ends reasoning as well as evaluative reasoning about the good must belong exclusively to the rational part. When the non-rational parts motivate, they do so through perception, memory, and the ability to envision prospects. On Lorenz's reading, the brute within turns out to be a rather sophisticated animal, even if it lacks reason.
Lorenz acknowledges that the simple picture risks preserving the integrity of one part of the soul at the expense of another. Let us assume that I have a strong, appetitive desire for cigarettes, and infer that I must walk down to the corner store to buy some. But I am also averse to smoking on the ground that it is bad for my health. In such cases, it may seem like I have a rational desire to pursue a course of action that I have a rational desire to avoid (50). Lorenz responds that despite its dependence on reasoning, the former desire is still appetitive. Importantly, it does not involve the representation of a means-ends relationship on the part of appetite. Reason can cause appropriate representations to arise in the appetitive part without this part itself being capable of understanding or articulating means-ends relationships.
The remainder of the book is devoted to fleshing out this proposal by examining such loci classici as the painter and scribe passage in the Philebus, as well as the analysis of perception and belief in the Republic, Theaetetus, and Timaeus. He segues into a discussion of the roles that perception and phantasia play in Aristotle's discussion of animal locomotion in De anima and De motu animalium. The analysis reveals that for Aristotle, as well as for Plato, means...