Abstract
The Republic represents the good life as some sort of harmony or composition between the different interests of which the threefold nature of the soul makes it capable. The rational factor, τ λολιστικν, not only chooses which impulses shall be satisfied and which rejected but is credited also with impulses of its own, such as the desire for knowledge, to the importance of which the Republic testifies by various strands of argument. But in Plato's attempt to prove the goodness of this mixed life he may be thought to have relied too much on arguments about its pleasantness. If he had really meant from the first to prove against Thrasymachus that the just life is more prolific in pleasure1 than the unjust, he would have had to undertake the task of proving a necessary connection between just activities and pleasant states of feeling which could scarcely exist unless feelings were under the control of the will. If this had been his intention, the whole weight of the argument would rest on the two comparatively short passages in Book IX in which he makes first a dubious appeal to experience and then, by an equally dubious piece of metaphysics, attempts to reinforce his ethical conclusion by denying the reality of such pleasures as might tend to throw doubt on it.