In De Officiis, Cicero values very highly the little society of parents and their children: an origin of society and seedbed of the republic, whose members should rank extraordinarily high among each other’s priorities. In light of Cicero’s biography and longstanding interest in a philosophical debate about parental love, I argue that Cicero’s position is that nature gives to humans a non-rational desire to care for their children, which leads many parents to rational love of their children, whereby they care about what is natural for at least some other humans, their children, as they care about it for themselves, holding property in common within the household. The rest of the family thereby learn loving attitudes. Such parents and their home are for their children images, however flawed, of virtue and a virtuous society. By making this experience common, nature teaches a lesson in what virtuous altruists would be like.

In the first book of his Tusculans, Cicero gives two arguments that the soul is eternal. Specifically, he concludes that each human soul’s rational part or ‘mind’ (mens) neither came to be nor will perish. I shall argue that in pursuit of this conclusion, Cicero constructs the position that, at least in this life, the human mind does not ‘sense’ itself, but knows about itself only by inference from its ‘sensations’ of other objects. First, the question of the mind’s sensation of itself is comparable to current debates about consciousness, for example to questions relating to the ‘hard problem’ of consciousness. To put it crudely, the ‘hard problem’ is that we suppose that our minds are conscious of themselves immediately, and that what we seem to learn from this immediate self-consciousness is that our minds are so different from the natural world we observe through the senses that it is a puzzle to understand how the two could be as intimately related as they appear to be.

In Book 2 of Cicero’s On the nature of the gods, Balbus argues for a Stoic theology and view of religion, and in Book 3 Cotta, an Academic skeptic, argues against him. I argue that both characters are supporters of traditional Roman pagan religion. In contrast to the Epicurean Velleius in Book 1, Balbus argues that the gods do care for us, in fact that the cosmic god fates every detail of our lives. He describes a world whose beauty is a principle reason to think that this rational creator has planned it for us, and further argues that this creator is good. He offers a complex rereading of Roman religion and poetic myth, according to which Roman religious practices were begun in ways that Stoic theology can support, and that it can still support once later distortions of this theology have been cleared away. Cotta, a pontifex, says that his skepticism is consistent with his priestly office, on grounds reminiscent of modern fideism. But he argues that Balbus’ dogmatic Stoic theology would destabilize the beliefs of those practising Roman religion, because Balbus cannot rigorously relate the many Roman gods to the one Stoic cosmic god.

In Book 1 of On divination, Cicero’s brother Quintus, who is not a Stoic, presents the Stoic case that all the many forms of divination at Rome are channels of divine communication. He does so explicitly in response to the arguments of On the nature of the gods, to strengthen the case that the gods care for us. I argue that his speech, which scholars have often called confused, can be better understood once we see it as a continuation of On the nature of the gods. For he speaks about not the, or even one, Stoic defence of divination, but rather two different Stoic views. The first is the view of Chrysippus, according to which divination was an art of interpreting messages from the gods. This view was challenged by the skeptic Carneades, and Cotta reissued some of this challenge in On the nature of the gods. Quintus recruits a new view in answer to this challenge, according to which some divination (e.g. augury, haruspicy, astrology) is artificial in that its divination meaning is first discovered by an art, but some is natural, in that some dreams and oracles have divinatory meaning without the use of an art.

Cicero says that almost no philosophers held atheism or agnosticism. For him the Central Question of philosophy of religion is not the existence of the gods, but whether the gods care for us by providence. He says we must answer this question to moderate religion. I argue that although traditional Roman pagan religion required orthopraxy, and not orthodoxy, Cicero thinks that the actions of a pagan practitioner could be "moderated" by what she believed about her religious behavior: if she believes that the gods care for us more than they do, that is superstition, but if she believes that they care for us less than they do, that is impiety. Yet Romans, Cicero says, were bewildered by their ancestral religion. He offers Hellenistic philosophy as a new route to responsible beliefs about it. Philosophy might help a Roman form true beliefs on the Central Question, or (like Cicero) to refrain from risky beliefs either way. On the nature of the gods and On divination are carefully designed to present this debate, among Stoics, with rich theories that the gods care and give us divinatory information, Epicureans, with rich theories to the contrary, and Academics, who withhold judgment.

Nineteenth and early twentieth century scholars thought Cicero a bad source for Hellenistic philosophy. They thought that the speeches in his dialogues were translated, often badly, from single sources. Thus they read him only to reconstruct his sources by Quellenforschung. I first give a sympathetic account of these scholars’ projects, which is often dismissed too easily today. Second, I give a complete argument that these scholars were wrong, and that today’s more positive, but often incompletely defended, view of Cicero is correct. Third, I argue that Cicero wrote dialogues not only to introduce Hellenistic philosophy to a Latin audience, but also as literary unities to impress a learned Roman audience who already knew philosophy in Greek. His models for the dialogue form were Plato, Aristotle, and Heraclides of Pontus, but he adapted it to to serve his radical Academic skepticism, in which he followed Carneades and Clitomachus. He hoped to be the model for a Latin tradition of good writing about philosophy, that would "illuminate" both philosophy and Latin. Cicero’s creativity as a philosophical author shows why Quellenforschung failed, and that he is a good source for Hellenistic thought.

Being a radical Academic skeptic, Cicero as author does not endorse an answer to the questions of On the nature of the gods and On divination. But when he portrays himself as a character in the dialogues, he portrays himself as finding plausible on those occasions a consistent philosophicaltheology and view of religion. I suggest that this is meant to model the free reaction of a skeptical mind to debates on questions where the skeptic forms no beliefs. The view that Cicero portrays as plausible to "himself" is the Stoic theology that the natural world is divine and benevolent, except that he finds implausible the Stoic view that divination delivers information from the gods (although he says that divinatory practices at Rome should continue for other reasons). Taking this attitude would be one way to "moderate" Roman religion, that is, to avoid impiety and superstition in practising it, but the reader is left free to make up his or her own mind.

In Book 1 of Cicero’s On the nature of the gods, Velleius argues for an Epicurean theology and view of religion. Cotta, an Academic skeptic, argues against him. I argue that when we see Cicero’s creative hand adapting Epicurean texts like the On Piety found at Herculaneum and attributed to Philodemus, we find that Velleius’ speech may be understood as proceeding from our allegedly natural concept that the gods are eternal and happy. Velleius’ seemingly intemperate criticism of his opponents, that they are crazy, follows from his position that they have somehow gone against this natural concept. His positive view, which proceeds from the happiness or blessedness (beatitudo, beatitas, eudaimonia) of the gods, is that Roman religion may be reinterpreted as worship of gods who do not care about us at all, and thus are ideals for us of the hedonist life free from pain. Despite Cicero’s habitual contempt for Epicureanism, he paints an attractive picture of Velleius’ spirituality. But Cotta argues that by making the gods not care for us, Epicurus has torn out the heart from religion, since he has made gods who are (so Cotta argues) selfish and not worthy of worship or imitation.