Relativity plays an important role in the skeptical outlooks of the Pyrrhonian skeptic Sextus Empiricus and of his predecessor Aenesidemus. But in the evidence concerning the earliest phase of Pyrrhonism, that of Pyrrho himself and his disciple Timon, there is no explicit mention of relativity. Nevertheless, there is good reason to suppose that it played an important role in their thinking. This is suggested both by the remarks at the opening of Diogenes Laertius’ life of Pyrrho, and by the summary by the Peripatetic Aristocles of an account by Timon of the early Pyrrhonist outlook. There is much about both these texts that is in dispute: whether they express a metaphysical view or epistemological reservations, whether the view applies only to questions of value or is global in character, and, on the Aristocles passage, how much of it represents Pyrrho’s ideas and how much just Timon’s. But on any plausible reading of these passages, there is a clearly implied emphasis on the variable ways in which things strike us, and this suggests a fundamental interest in relativity, even if it never surfaces explicitly.

This chapter examines several individuals and groups associated with the court of the Sasanian king Khusrō I (r. 531–79), detailing their respective religious and philosophical orientations, and the historical connections among them. The people in focus include, among others, Burzōy, author of the Vorlage for Ibn al-Muqaffaʿ’s Kalīla and Dimna, the Neoplatonists who supposedly left the Academy at Athens for the Sasanian court, and Khusrō I himself. While it is unlikely that the commonalities among these thinkers’ views are rooted in a shared debt or adherence to a specific tradition or school, they do attest to a broader philosophical and more specifically epistemological ferment in the later Sasanian empire, which continued into the time of Muslim rule.

This chapter challenges the assumption that placing a “human in the loop” is an adequate safeguard against the harms of AI. It introduces the concept of automation bias – a cognitive tendency for human decision-makers to over-rely on automated systems, often ignoring contradictory evidence or their own training. The chapter demonstrates how the human operator can become a mere “rubber stamp” for a flawed machine.

The risk is magnified with generative AI (GenAI), whose polished, authoritative-sounding outputs and ubiquitous availability deepen trust and erode critical thinking, leading to both errors of commission (following bad advice) and errors of omission (failing to monitor for errors). The chapter concludes that effective mitigation requires more than just human oversight; it demands intentional changes to system design, organizational culture, and human training to foster a healthy skepticism toward AI recommendations.

This chapter provides two practical frameworks for navigating the pervasive hype surrounding generative AI (GenAI). The first is a consumer handbook for critically reading AI-related news and press releases, urging skepticism toward unsubstantiated skill claims, proprietary benchmark scores, and “demo-ware,” while prioritizing independent third-party review. The second framework introduces “GenAIuflecting” – the unwarranted deference governments show to AI companies – and offers practical tests (the evidence, substitution, beneficiary, accountability, and precedent tests) to identify and resist policy proposals that favor corporate profit over public interest. Ultimately, the chapter argues that the true stakes are not winning an “AI race,” but securing democratic control over technology’s role in society.

Recognized as the preeminent figure in Brazilian literature, Chapter 7 examines Machado de Assis through the lenses of five key concepts: Modernism, skepticism, satire, digression, and the “instinct of nationality.” The chapter explores how Machado’s fiction employs these elements as artistic resources and narrative techniques. Modernism is primarily characterized by intertextuality, while Machado’s skepticism is intimately tied to his satirical mode, both of which interpret history as an ongoing cycle of repetition. This cyclical nature of history parallels the sinuosity inherent in his use of digression. Collectively, these dimensions coalesce to articulate Machado’s vision of Brazil, which is embodied in his major works through representations of the Brazilian elite and their paradoxical dynamic of embracing modernity while simultaneously undermining it.

The chapter-length Introduction establishes the historical and philosophical contexts for the Romantic reimagining of persuasion. A section on David Hume’s skeptical views on “perswasion” and the influential response to them by the Scottish rhetorician and minister George Campbell draws important terminological distinctions and delineates key features of the inquiries and reimaginings addressed in the chapters that follow. The main features of the concept of malleable persuasion are described and differentiated from adjacent concepts in works by Lord Byron, Edmund Burke, and Mary Shelley, among others. The book is situated in relation to major lines of scholarship on Romantic cultures of controversy, secular casuistry, and the histories of belief and skepticism. The chapter ends by addressing the distinctly literary dimensions of persuasion, including the role of reading in its representation and elicitation, and the formal resources involved across genres.

Chapter 1 delineates the overlapping new paradigms of persuasion elaborated by Thomas De Quincey and William Hazlitt in response to George Campbell and David Hume, and considers their implications for the genre of the periodical essay. Against Campbell’s definition of persuasion as an emotional supplement to rational conviction, De Quincey and Hazlitt, in their essays of the 1820s and 1830s, formulate the alternative of a self-consciously partial and flexible way of holding and forming beliefs. De Quincey’s performance of such persuasion in “On Murder Considered as One of the Fine Arts” makes apparent the problem of anything-goes judgment that leads him, in his “Rhetoric” and “Style” essays, to restrict persuasion to “subjective” domains like rhetoric and poetry. Hazlitt, by contrast, in his late-career essays on belief, opinion, and controversy, endorses malleable persuasion in all domains of dispute and theorizes its unique affinity with imaginative literature.

“Common sense” has multiple meanings, some of them familiar and others less so. This chapter pursues the themes of Chapter 6 by disentangling five meanings of common sense and examining how Arendt uses them in her own epistemology. Hers, I argue, is a version of social epistemology, in which the reliability of empirical knowledge turns not only on our own capacities but also on the comparison of our judgments with those of others. Even though Arendt was deeply concerned about skepticism and the collapse of common sense, and occasionally wrote about the philosophical problem of radical skepticism, this chapter argues that she ultimately rejects the problem rather than attempting to solve it.

Thomists and contemporary epistemologists don’t often seem to have much to say to one another. I here argue that Thomism fits very well with at least one school of thought in contemporary epistemology: commonsensism. I prosecute my case by arguing that Étienne Gilson’s dismissal of commonsense philosophy as incompatible with Thomistic realism is a mistake. I begin by outlining commonsensism. I then proceed to a discussion of Gilson’s rejection of commonsense philosophy. I finish by arguing that Gilson’s criticisms fail and that Thomists should be commonsense epistemologists.

This chapter explores Pascal’s skeptical outlook, highlighting his innovations as well as his reliance on older, more familiar arguments. To begin with, Pascal thought that reason itself could not provide the foundations or first principles of geometry or our knowledge of space. These first principles are not only unsupportable by any proof, so that reason itself provides them no certainty, but they in turn provide materials for further uncertainty given potential infinities in space – both the largeness and smallness of space seems to have no bounds. The result is that we cannot, by appeal to reason alone, find our place within the physical universe. Similarly, and contra Descartes, no proof of God can guarantee that life is not one long dream, so belief in the external world itself cannot be supported by reason. Nor can our experience of the world prove the existence of God in any useful way. The result is that our reason and experience, operating on their own, are insufficient to establish much of anything foundational. The appeal to proofs and evidence cannot resolve other controversies of our day, either, as anyone who has tried to convince a conspiracy theorist by such methods will know.

This chapter examines the three foundational strands that shaped early Christianity and, in turn, western thought: Judaism, Hellenistic philosophy, and Roman culture. It begins with Judaism, emphasizing its monotheism, prophetic self-criticism, and teleological view of history – features that deeply influenced Christian theology. The Book of Isaiah is central, offering themes of justice, suffering, and messianic hope later interpreted as prefiguring Christ. The chapter then turns to Hellenistic philosophy – especially, Stoicism, Skepticism, and Epicureanism – which informed Christian ideas about the soul, virtue, and the good life. These schools stressed moral discipline and the pursuit of wisdom, values that Christianity absorbed and reinterpreted theologically. The Roman contribution centered on imperial power, civic virtue, and especially the Latin language, which became Christianity’s primary medium in the West. Roman thinkers like Cicero and Virgil helped transmit Greek ideas, emphasizing duty, eloquence, and destiny. These strands – Jewish, Greek, and Roman – were not seamlessly integrated, but their dynamic interaction laid the groundwork for a western intellectual tradition rooted in moral inquiry, historical depth, and a universalizing spiritual vision.

In the first part of Chapter 5, Goodman considers some basic affinities of Emerson and Montaigne that are evident even before Emerson published “Montaigne, or the Skeptic”: their use of the essay form to register spontaneity and contingency, their critique of books and travel, their discussions of the play of moods, their attention to themselves. The second part of Chapter 5 considers the shape of Emerson’s Montaigne essay, which has its own moods and its own architecture, and which concludes by taking what the critic Barbara Packer calls “a miraculous act of levitation” outside the play of moods to the moral sentiment that “outweighs them all.” In evaluating this leap, Goodman deploys Emerson’s own skepticism against his more metaphysical and dogmatic tendencies. “Why so talkative in public,” he writes, “when each of my neighbors can pin me to my seat by arguments I cannot refute?”

Chapter 9 considers Emerson’s first revolutionary book of 1836, Nature. Even in this first book, Goodman argues, Emerson presents a nascent epistemology of moods. The discussion then turns to the moody swings of “Nature,” from the Essays, Second Series, in which Emerson finds the natural world either bountifully present or just missed, and as taking two opposing forms: a stable finished form he calls natura naturata, and a dynamic form he calls natura naturans. At the end of the essay, Emerson abandons this main set of oppositions in a leap to a metaphysical conclusion. The Coda considers Emerson’s attraction to Michael Faraday’s idea that “we do not arrive at last at atoms, but at spherules of force.”

Emerson describes a range of experiences that constitute friendship: titanic battles between beautiful enemies; conversational brilliance and expansion; a joyful solitude, as if someone has departed rather than arrived; a generalized benevolence toward people in the street to whom one does not speak; the warm sympathies and household joy one shares with a familiar friend; the disappointment of a friend outgrown. His account shows an intense focus on moral perfection – on our unattained but attainable self, alone and with others – but an equally intense awareness of what he calls in “Experience” “the plaint of tragedy” that sounds throughout our lives “in regard to persons, to friendship and love.” The chapter’s coda charts the opposition in “Love” between love as the experience of being “swept away” and a skeptical vision of marriage as a prison, from which sex, person, and partiality have vanished.

Chapter 4 begins by tracing some reappearances and interconnections of Emersonian themes, in what Goodman calls paths of coherence in Emerson’s philosophy: not a complete system, but ways that his thoughts hang together. The chapter focuses on “Nominalist and Realist,” where Emerson sets out the competing metaphysics of particulars and universals without reconciling their opposition. Near the end of the essay, he draws a skeptical lesson from his epistemology of moods. “I am always insincere,” he writes, “as always knowing there are other moods.” This might be cause for despair, but Emerson’s tone in this final paragraph is more in tune with ancient skepticism and Montaigne. He ends “Nominalist and Realist” by withdrawing from the dispute, but this does not mean that he gives up inquiring. Skepticism can be both a withholding of final judgment, and, as Herwig Friedl observes, “a constant looking around, without any attempt at closure.”

While it is important to trace Emerson’s main positions, one misses the living nature of his philosophy unless one also takes account of the motions, moods, and patterns within his essays, and the ways he dramatizes instability, spontaneity, and inconsistency. This emphasis is found in Goodman’s discussions of “History” in Chapter 1, “Friendship” in Chapter 3, “Nominalist and Realist” in Chapter 4, “Manners” in Chapter 6, “Experience” in Chapter 7, “Nature” in Chapter 9, and “Illusions” in Chapter 10. Chapter 2 distinguishes the sheer variety of skepticisms in Emerson’s thought, about the world and other minds, but also about mystical experiences that refuse “to be named” or are “ineffable.” It also attends to the differences between the “modern” tradition of skepticism as doubt, and skepticism as a form of life, with Emerson’s essay on Montaigne a key source for his idea of a “wise skepticism.”