This chapter assess the philosophical foundation for Cicero’s views on human social relationships and community in the Roman Republic. Starting from De officiis 1.153, I argue that such a foundation is provided by the specifically Stoic notion of the community of gods and human beings, and of human beings as sharing rationality. The De officiis is then assessed on the basis of Cicero’s emphasis on the social aspect of virtue. The remainder of the chapter traces this same theme throughout Cicero’s theoretical writings (including his works on rhetoric), first in the earlier De inventione, De legibus, and De republica, and second in the De finibus and the Tusculanae Disputationes. Hence the commitment to this Stoic foundation for sociability is a constant in Cicero’s oeuvre.

Plato was for Cicero the prince among philosophers. Cicero himself identified with Plato in all his richness and abundance as a writer and thinker, but also as a model for the politically engaged intellectual. This chapter studies first Plato’s presence in Cicero’s letters in the period 54–49 bce, the tempestuous years before the Roman Republic was finally torn apart. Then it turns to consider the three major Platonic dialogues composed at that time: De oratore, De republica, De legibus, in which he articulates grand political and cultural ambitions for the orator and a vision of how a republican polity should and could be conceived and conducted. A brief final section looks at the theoretical writings on oratory and philosophy in 46–44, mostly composed during Caesar’s dictatorship, when Cicero’s voice in the public sphere was almost entirely silenced. His main literary efforts were devoted to the construction of a philosophical encyclopedia, in which the systems of the Hellenistic schools became the main focus. His veneration of Plato and his attraction to Platonic idealism in various aspects remain evident. But the intensity of his earlier engagement with Plato has become a thing of the past.