A textbook for graduate students of philosophy, computer science, and mathematics, on various approaches to nonmonotonic logic, with emphasis on they way in which they fall into an overall pattern.

Errol Lord offers a new account of the nature of rationality: what it is for one to be rational is to correctly respond to the normative reasons one possesses. Lord defends novel views about what it is to possess reasons and what it is to correctly respond to reasons, and dispels doubts about whether we ought to be rational.

In this volume, John Horty brings to bear his work in logic to present a framework that allows for answers to key questions about reasons and reasoning, namely: What are reasons, and how do they support actions or conclusions?

Evidentialism is a popular theory of epistemic justification, yet, as early proponents of the theory Earl Conee and Richard Feldman admit, there are many elements that must be developed before Evidentialism can provide a full account of epistemic justification, or well-founded belief. It is the aim of this book to provide the details that are lacking; here McCain moves past Evidentialism as a mere schema by putting forward and defending a full-fledged theory of epistemic justification. In this book McCain offers (...) novel approaches to several elements of well-founded belief. Key among these are an original account of what it takes to have information as evidence, an account of epistemic support in terms of explanation, and a causal account of the basing relation that is far superior to previous accounts. The result is a fully developed Evidentialist account of well-founded belief. (shrink)

An graduate level introduction to nonmonotonic reasoning, emphasizing structures and spirit common to different formulations, with exercises.

Evidentialism holds that the justified attitudes are determined entirely by the person's evidence. This book is a collection of essays, mostly jointly authored, that support and apply evidentialism.

Formally-inclined epistemologists often theorize about ideally rational agents--agents who exemplify rational ideals, such as probabilistic coherence, that human beings could never fully realize. This approach can be defended against the well-know worry that abstracting from human cognitive imperfections deprives the approach of interest. But a different worry arises when we ask what an ideal agent should believe about her own cognitive perfection (even an agent who is in fact cognitively perfect might, it would seem, be uncertain of this fact). Consideration (...) of this question reveals an interesting feature of the structure of our epistemic ideals: for agents with limited information, our epistemic ideals turn out to conflict with one another. (shrink)

It has often been noticed that conciliatory views of disagreement are "self-undermining" in a certain way: advocates of such views cannot consistently maintain them when other philosophers disagree. This leads to apparent problems of instability and even inconsistency. Does self-undermining, then, show conciliationism untenable? If so, the untenablity would extend not only to almost all views of disagreement, but to a wide range of other views supporting what one might call epistemic modesty: roughly, the idea that getting evidence that one (...) has made an epistemic error in arriving at one’s opinion may require adjusting that opinion. This paper argues that the phenomenon of self-undermining does not disclose any defect in views mandating epistemic modesty. Instead, it highlights an uncomfortable but natural consequence of reflecting on one's own possible epistemic imperfections, a sort of reflection that tends to cause epistemic ideals to conflict. (shrink)

My dissertation is a systematic defense of the claim that what it is to be rational is to correctly respond to the reasons you possess. The dissertation is split into two parts, each consisting of three chapters. In Part I--Coherence, Possession, and Correctly Responding--I argue that my view has important advantages over popular views in metaethics that tie rationality to coherence (ch. 2), defend a novel view of what it is to possess a reason (ch. 3), and defend a novel (...) view about what it is to act and hold attitudes for normative reasons (ch. 4). In Part II--Foundationalism, Deception, and The Importance of Being Rational--I argue that foundationalists about epistemic rationality should think that the foundational beliefs are held for sufficient reasons (ch. 5), argue that my view solves the New Evil Demon problem for externalism (and solves a related and underapprieciated problem) (ch. 6), and argue that my view can vindicate the thought that we ought to be rational (ch. 7). (shrink)

Suppose a rational agent S has some evidence E that bears on p, and on that basis makes a judgment about p. For simplicity, we’ll normally assume that she judges that p, though we’re also interested in cases where the agent makes other judgments, such as that p is probable, or that p is well-supported by the evidence. We’ll also assume, again for simplicity, that the agent knows that E is the basis for her judgment. Finally, we’ll assume that the (...) judgment is a rational one to make, though we won’t assume the agent knows this. Indeed, whether the agent can always know that she’s making a rational judgment when in fact she is will be of central importance in some of the debates that follow. (shrink)

Epistemic akrasia arises when one holds a belief even though one judges it to be irrational or unjustified. While there is some debate about whether epistemic akrasia is possible, this paper will assume for the sake of argument that it is in order to consider whether it can be rational. The paper will show that it can. More precisely, cases can arise in which both the belief one judges to be irrational and one’s judgment of it are epistemically rational in (...) the sense that both are supported by sufficient evidence. (shrink)

Evidence is univocal, not equivocal. Its implications don't depend on our beliefs or values, the evidence says what it says. But that doesn't mean there's no room for rational disagreement between people with the same evidence. Evaluating evidence is a lot like polling an electorate: getting an accurate reading requires a bit of luck, and even the best pollsters are bound to get slightly different results. So, even though evidence is univocal, rationality's requirements are not "unique." Understanding this resolves several (...) puzzles to do with uniqueness and disagreement. (shrink)

The goal of this paper is to frame a theory of reasons--what they are, how they support actions or conclusions--using the tools of default logic. After sketching the basic account of reasons as provided by defaults, I show how it can be elaborated to deal with two more complicated issues: first, situations in which the priority relation among defaults, and so reasons as well, is itself established through default reasoning; second, the treatment of undercutting defeat and exclusionary reasons. Finally, and (...) by way of application, I show how the resulting account can shed some light on Jonathan Dancy's argument from reason holism to a form of extreme particularism in moral theory. (shrink)