This chapter presents an overview of Plato’s moral realism. The metaphysical framework of Plato’s moral realism is explained. This framework’s fundamental principle is the superordinate Idea of the Good, which is both the anchor for moral realism and the unhypothetical first principle of all. Thus, for Plato normativity is woven into metaphysics (Section 1.1). A taxonomy of types of moral realism is provided within which Plato’s moral realism can be situated (Section 1.2). Plato’s moral realism is compared to versions of antimoral realism and naturalistic versions of moral realism (Section 1.3). The priority of “good” to “right” in Plato is explained (Section 1.4). The priority of “good” to “value” is further explained. The universality of the Good goes beyond objectivity and is intended to preclude the possibility that “good” and “good for me” can possibly conflict (Section 1.5).

In this chapter the account of the Idea of the Good as the foundation of moral realism is applied to issues in religion and politics (Section #1). The question is raised and answered why Plato is confident that the gods are only good and not ever bad (Section #2). The theology of Laws10 is examined for some of the theological implications of the preeminence of the Good (Section #3). The concept of religious experience is introduced and its metaphysical underpinnings explained (Section #4). The problem of evil is addressed: how can the Good, the archē of everything, be the cause of evil? If it is not the cause, whence evil? (Section #5). The tensions between a metaphysics of the Good and the exigencies of politics, especially the authority of rulership, is examined (Section #6). The idea of the common good is introduced in order to determine if it is possible that the common good and the private good should conflict and if so, how does this impact Plato’s universal Good (Section #7). The connection between political expertise, consent, and legitimacy of types of government is examined (Section #8)

The widespread view that so-called Socratic ethics is fundamentally different from Platonic ethics is examined. The so-called Socratic paradoxes are discussed (Section 4.1). The idea of Socratic ethics as independent of any metaphysical assumptions is critically examined (Section 4.2). The so-called Socratic intellectualism is examined and the claim that in Protagoras Socrates rejects the idea of incontinence is criticized (Section 4.3). The account in Protagoras of “being overcome by pleasure” and the possibility of incontinence are examined as a possible key to differentiating Socratic and Platonic ethics (Section 4.3). The connection between virtue and happiness in the “Socratic” dialogues and in the “Platonic” dialogues is explored. What is the connection between happiness and the Idea of the Good (Section 4.4)?

This chapter is focused on aspects ot the superordinate Idea of the Good. Why is the first principle of all a normative principle (Section 2.1)? How does the Idea of the Good differ from an “ordinary” Form of the Good (Section 2.2)? Why is the unhypothetical first principle of all also the goal of everything, that which all desire (Section 2.3)? How does the Idea of the Good differ from the Demiurge? Why is the Demiurge good but not the Good (Section 2.4)? How is the admonition in Theaetetus to “assimilate to god” related to the Good as goal (Section 2.5)? In Symposium, the relation between eros and the Good is explored (Section 2.6). In Lysis, the idea of a “prōton philon” is comapred to the Idea of the Good as goal (Section 2.7). The evidence frrom Aristotle and from the indirect tradition that Plato identified the Good with “the One” is assembled. Why is oneness an index of goodness? The idea of integrated unity according to kind is introduced (Section 2.8).

Moral realism in Philebus and Statesman are explored in this chapter. Plato’s later dialogues focus on this-worldly issues within a larger metaphysical framework (Section 6.1). Integrated unity according to kind is explained in relation to the good life. In Philebus Plato provides us with a criterion for the presence of manifestations of the Good: the complex unity of truth, beauty, and symmetry. The Good can be understood to be manifested in the sensible world. In Statesman, the ideal statesman turns out to be different from the philosopher (Section 6.3). The ideal for anything is integrative unity according to kind. As Plato says in Republic, the virtuous person “becomes one out of many” (Section 6.2). Plato also outlines a type of hylomorphic composition according to which the Good can be a this-worldly Demiurge instantiating goodness in the polis and in its inhabitants. The skill thus displayed is now seen to be different from that of the philosopher (Section 6.3).

Plato consistently holds that “no one does wrong willingly.” If this is the case, how is it possible for someone to be held morally responsible for his actions? Plato does seem not only to countenance the idea of moral responsibility but to make it a central notion in his political and eschatological writings (Section 5.1). The connection between personhood and embodiment is explored and the relevance of embodiment to moral responsibility is considered in Republic and Timaeus. The possibility of incontinence or akrasia reveals the divided selfhood in the emboodied person. The concept of culpable ignorance is introduced in order to account for moral responsibility. Culpable ignorance depends on the self-relexivity of rationality (Section 5.2).

The connection between virtue and knowledge is explored in this chapter. Various accounts of Plato’s ethics attempt to focus on the so-called Socratic paradoxes and then try to show how Plato can be seen to have constructed a psychology of action to defend these paradoxes. What is it that these paradoxes try to teach us about morality (Section 3.1)? What is “Socratic” knowledge knowledge of? How is knowledge of the Idea of the Good supposed to be relevant to morality (Section 3.2)? Virtue is a human good but so are health and wealth, friendship, and pleasure. How does Plato’s moral realism deal with these goods when they conflict (Section 3.3)? What does the practice of philosophy have to do with virtue? Can one be virtuous without being a successful philosopher (Section 3.4)? The gradations of virtue in the dialogues and their metaphysical foundation are discussed (Section 3.5). What does the Idea of the Good add to an account of human virtue or excellence (Section 3.6)? This is followed by a comparison of motivation in Plato and Kant (Section 3.7).

In this concluding chapter, I bring together the main themes of the book, focusing on the primacy of the Idea of the Good and its universality. I make some concluding remarks on the tensions that arise for the conflation of Plato’s moral realism and politics.

The present volume is the ‘successor’ to The Cambridge Companion to Plotinus (1996). Over the last twenty-five years, there has been an enormous increase in published work on Plotinus and on late ancient Platonism generally. In addition, many scholars who had not even begun their careers twenty-five years ago are now working intensely in this area. This fact is reflected in the list of authors of this volume, none of whom appeared in the previous work and most of whom had not yet even begun their careers when the original Companion appeared.1

Nature for Plotinus is near the limit of intelligibility in the hierarchical universe. It is the lowest part of the soul of the cosmos. Hence, all problems in cosmology and biology, prior to their solution, need to be situated within the framework of the ultimate metaphysical explanatory principles of the One, Intellect and Soul. This chapter explores the sense in which Plotinus is and is not receptive of panpsychism, the contemporary philosophical view according to which mentality or consciousness is ubiquitous in the world. Plotinus argues for the idea that nature contemplates which seems, perhaps surprisingly, compatible with the radically anti-Platonic naturalism of panpsychists.

At first glance, Plotinus’ arguments for the immortality of the human soul, principally in Ennead IV 7 (2), constitute a straightforward defense of Plato against Peripatetic and Stoic attacks. And yet, his close reading of his predecessors, especially Aristotle and Alexander of Aphrodisias, led him to confront the following deep problem. The best arguments for immortality rest upon the immateriality of intellect and hence its immunity from destruction along with the body. But, following Aristotle, Plotinus maintains that the nature of intellection is such that the contents of the objects of intellection both identify the agent of intellection and further will be identical for every disembodied intellect. For this reason, it is not clear what it would mean to insist on the personal immortality of anyone. Without personal immortality, though, the ethical dimension of Platonism is, for Plotinus, severely undermined. In the light of this difficulty Plotinus developed an apparently original doctrine that was repudiated by virtually all his successors. He argued that there are Forms of individuals, that is, of individual intellects, and that, since they are eternal Forms, they are ‘undescended’. He argued that the personal identity of any human soul is found paradigmatically in an undescended intellect.

The distinctive features of Plato’s philosophical system are examined, especially his rejection of naturalistic philosophic and scientific approaches and his postulation of an absolutely simple first principle. The Platonists after Plato are then considered, including Aristotle, Alcinous, Numenius, Plotinus, Iamblichus, Proclus. Platonism is conceived as a collaborative project that developed over against opposition – such as Stoicism and, in late antiquity, Christianity – as well through internal debates among its rival schools. The chapter concludes with a discussion of Platonism’s encounter with Christianity after the Edict of Milan.