Abstract

In Plato's mature moral psychology the conception of the relation between a rational agent's own good and the good of others is robustly non-egoistic. This is because Plato's mature moral psychology considers the dominant component of the self-interest of a rational agent to be the agent's maximal contribution to the actualization of the unrestricted good, that is to the good of everything and anything. This dominant component is defined by reason's desire for the unrestricted good. This desire provides the key to understanding three crucial components of Plato's philosophy: first, the relation between self-interest and justice , which explains the philosophers' rule in the model polis of the Republic; second, the gods' governance of the universe, which is a fundamental claim of Plato's cosmology; and third, the homoiosis theoi doctrine of later dialogues which claims a human becomes happy by imitating gods. The three components may be brought together as follows. ;The recognition of the rational desire for the unrestricted good supplements the deficiency model of desire which Plato employs in earlier dialogues, such as the Lysis and the Symposium. This model, the crucial claim of which is that there can be no desire without some deficiency in the one who desires, must be supplemented in order to provide some explanation of the desire of the gods, who are not defective in any way, to govern the universe. Since the gods are above all characterized as rational, their desires naturally spring from the nature of reason itself. Precisely in so far as humans are rational they share this desire. It is because humans share the desire of the gods that human happiness depends on imitating gods, as the homoiosis theoi doctrine suggests. And it is precisely by imitating the gods' governance of the universe that the philosophers who govern the model polis achieve the pinnacle of this-worldly human happiness