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.

This book has looked at some familiar doctrines from a different perspective. The doctrines were that sensibility is a kind of mean and that intelligence is something single, separate, unmixed; the perspective was to see these doctrines as filling out Aristotle’s explanation of why it is in human nature to perceive and to understand beings. The core of that explanation is that sensibility and intelligence are “forms” or “measures” of their respective objects, perceptible and intelligible beings; to see the doctrines just alluded to as “filling out” this core is to see them as specifying those forms or measures (in the one case as a kind of mean, in the other as something simple, separate, or unmixed). The upshot is that there is a kind of priority of sensibility and intelligence to perceptible and intelligible beings. Some will find this upshot un-Aristotelian: doesn’t he hold that perceptible and intelligible beings are causes of and (therefore) prior to perceptual and intellectual knowledge? In this concluding chapter then I try to meet this and similar concerns, by way of clarifying the perspective I have been developing.

Aristotle represents many of his predecessors as having arrived at their views about psuchē from reflection on the fact that knowledge is of beings; it is this fact, together with the principle that knowledge is “like by like,” which led them to the view that psuchē is an amalgam of the elements of all beings. But though Aristotle thinks little of this view, he accepts the considerations (duly qualified) from which it is derived. Now, the principle that knowledge is “like by like” is an explanatory principle; it locates the “cause” of knowledge in an antecedent likeness between its subjects and objects. Moreover, analogous principles have been offered to explain analogous facts, and they too are principles which (duly qualified) Aristotle accepts. But though we might expect the qualifications to vary from case to case, still we might wonder whether there isn’t some point they all enforce. In this chapter I argue there is such a point: that the explanatory “likeness” between the parties in question is never just any likeness, such as obtains “as it happened” or by chance, but is always an antecedent likeness in some form common and natural to all parties involved.

In this chapter I argue that Aristotle is seeking, in the De Anima, to explain why it is in human nature to know beings (all beings). The argument rests in part on how Aristotle introduces his agenda and in part on a criticism he makes of his predecessors. I also discuss various qualifications that must be made to that introduction and that criticism in order to bring them in line with Aristotle’s considered views.

The most obvious use of philosophy within Cicero’s speeches is as a source of invective: Stoicism against Cato in the Pro Murena, Epicureanism in In Pisonem. However, even here Cicero is careful to show that philosophical adherence itself is not a fault; but only faulty adherence. Elsewhere in the speeches, Cicero draws on Stoic theories of society in constructing his views of the relationship between the res publica, crisis, and tyranny and in articulating the justification for tyrant killing: this line of argument can be traced from the Catilinarians through Pro Milone down to the Philippics.

In his treatises De divinatione and De fato, Cicero discusses the possibility of the prediction of future events. His understanding of divination in these philosophical works differs significantly from accepted Roman practice. Thus, De divinatione should not be read as a handbook on Roman divination. Rather, it should be read alongside De fato as an exhortation to act in the service of the res publica after the death of Caesar. Rather than denying outright that divination is real, Cicero seeks to refute the more superstitious divinatory practices current in Rome, all of which he attaches to the individual rather than to the political community to which he has dedicated his life. Among these superstitious views are the belief that humanity is subject to impersonal fate and therefore that human responsibility is curtailed. In writing for a Roman audience, Cicero denies both the notion that men cannot be responsible for their own actions, thus rejecting the idea of fate, as well as the existence of divination in the context of a deterministic worldview.