Many of Cicero’s translations of Greek concepts (assent, comprehension, quality) have become common terms in philosophy but also in ordinary language in many European countries. Some of them, pertaining to epistemology, ethics, or physics, are studied in this chapter to show why and how Cicero set out to create a Latin philosophical vocabulary. He wanted to extend the supremacy of Rome to an area formerly reserved to the Greeks. He tried to avoid technical terms or neologisms and preferred open notions to closed concepts. He aimed at conveying the complexity of Greek philosophical doctrines in Latin and sometimes brought out certain nuances which did not exist in the Greek terms (as in the case of probabile). Cicero’s originality as a philosopher does not lie in creating a new system but in providing philosophy with a new language and in promoting the idea that philosophy was not the privilege of Greek culture but a field open to human ingenuity.

This chapter is focused on Aristotle’s account of sensibility in De Anima II 12. My thesis is that the account defines sensibility as the standard in relation to which perceptible qualities are the sorts of quality they are. To illustrate, Aristotle holds that some colors are dark, others light; this implies that the spectrum of dark and light is “divided” into two “sides,” one dark, the other light. In the previous chapter I suggested that what it is for a quality to lie on one side of a spectrum – e.g. to be one of the dark colors – is a matter of its relation to the “middle” of the associated spectrum. In this chapter I argue that the claim that sensibility just is “as it were a kind of mean of the contrariety in perceptible qualities” implies that these “middles” are defined by sensibility itself, the form or essence of the primary sense organ. The upshot is that the senses are “forms” or “standards” of perceptible qualities, in that the particular qualities known by their means are the sorts of quality they are (e.g. dark colors or light ones) thanks to their relationship to the form of the primary sense organ.

This chapter asks what it is about “intelligence” (nous) that, in Aristotle’s view, makes “understanding” or “insight” (noēsis) its proprietary work. It argues that the answer lies in the peculiar clarity and distinctness of that activity. This clarity and distinctness, it argues, make intelligence the very “form” or “measure” of its objects – what they all “have in common,” what “makes” them intelligible, what their intelligibility consists in.

The chapter traces statements on Cicero’s philosophical position from his earliest treatise (on rhetorical theory) to the philosophical works of the 40s bce, while attending to the literary form of Cicero’s oeuvre. It argues that Cicero’s stance is stable over time, that it exhibits a number of features that would warrant calling it mitigated skepticism, but that, given the way different Academic positions are conceptualized in Cicero’s texts, notably the Academica, his position is formally one of radical skepticism. The chapter tries to identify features of the evidence from Cicero which are distinctive compared to other texts (e.g. by Sextus Empiricus and Numenius), notably an unusual wealth of comments on the practice of Academic skepticism (i.e. on what being an Academic skeptic was like, at least on Cicero’s construal and to what extent it was compatible with being a fully functioning Roman of a certain social class and with a particular occupation).

This chapter discusses Cicero’s views on the relation between ethical theory and the good human life, focusing on his main work on ethical theory, De finibus. Cicero’s critique of Stoic and Epicurean ethics has a common element, all the more striking given the differences between the two doctrines, namely that neither theory is livable with integrity in social contexts. This critique is a reflection both of Cicero’s belief that ethics should engage with lived human experience and of the commitment, in varying degrees, of the Stoics and Epicureans to a conception of the good human life as inherently social. The pluralism of the Old Academy’s ethics discussed in the final part of De finibus escapes this critique but is in danger, through lack of a single supreme value, of failing to offer a basis on which we may structure our lives. Taken as a whole, De finibus can thus be seen to cast a skeptical eye on the viability of ethical theory itself.

Disdain for Cicero is widespread among contemporary philosophers. This chapter shows this attitude is mistaken. It focuses on three topics where Cicero speaks to contemporary philosophical problems with special urgency and relevance: cosmopolitanism, aging, and friendship. Cicero’s analysis of the duties of justice and the duties of material aid in his De officiis became the foundation for much of modern international law. But his analysis suffers from a bifurcation: it makes the former fully global (national boundaries are irrelevant) and the latter very elastic. The topic of aging has been entirely neglected by philosophers. Cicero’s dialogue De senectute offers a defense of old age against stigma and prejudices: some arguments are unconvincing, but many are excellent and have much to teach us. In his De amicitia, Cicero offers a convincing critique of common self-insulating pictures of friendship and an exploration of friendship as an element of political life, of which Cicero’s long-lived friendship with Atticus is a perfect example.

This introductory chapter provides an overview of the book as a whole, which tries to put a question to Aristotle and to work out his answer to it as developed in the De Anima. The question, roughly put, is about Mind and World: what about the one makes it such as to know the other? The book’s principal contentions are, first, that this question is Aristotle’s, and second, that the nub of his answer is that in a way Mind is World – in his language, “psuchē in a way is all beings.”

This chapter presents Plato's specific contribution to the history of theoria: how he reacts to the notion of traditional theoria and specifically, which of its elements he rejects and which he reconceives. Platonic theoria stands, although somewhat uneasily, on the shoulders of traditional theoria in regard to its emphasis on observational performance rather than perceptual understanding: for Plato, the follower of traditional theoria is merely "a lover of sights and sounds" rather than a true philosopher. However, certain features are shared across traditional and Platonic theoria, such as that involving perceptual experience, being focused on objects of high significance and the idea of elliptical motion. These features are distinguished as falling along two planes, structural and philosophical, and discussed using analyses of Phaedo, Republic, Phaedrus, and Symposium, among others.