I present a straightforward objection to the view that what we know has epistemic probability 1: when combined with Bayesian decision theory, the view seems to entail implausible conclusions concerning rational choice. I consider and reject three responses. The first holds that the fault is with decision theory, rather than the view that knowledge has probability 1. The second two try to reconcile the claim that knowledge has probability 1 with decision theory by appealing to contextualism and sensitive invariantism, respectively. (...) I argue that each response fails, and that we can hold on to much of what was attractive in the responses while denying that what we know has probability 1. (shrink)

Wolfgang Spohn presents the first full account of the dynamic laws of belief, by means of ranking theory. This book is his long-awaited presentation of ranking theory and its ramifications.

This major work challenges some widely held positions in epistemology - those of Peirce and Popper on the one hand and those of Quine and Kuhn on the other.

"[This book] proposes new foundations for the Bayesian principle of rational action, and goes on to develop a new logic of desirability and probabtility."—Frederic Schick, _Journal of Philosophy_.

In these challenging pages, Unger argues for the extreme skeptical view that, not only can nothing ever be known, but no one can ever have any reason at all for anything. A consequence of this is that we cannot ever have any emotions about anything: no one can ever be happy or sad about anything. Finally, in this reduction to absurdity of virtually all our supposed thought, he argues that no one can ever believe, or even say, that anything is (...) the case. (shrink)

Knowledge and its Limits presents a systematic new conception of knowledge as a kind of mental stage sensitive to the knower's environment. It makes a major contribution to the debate between externalist and internalist philosophies of mind, and breaks radically with the epistemological tradition of analyzing knowledge in terms of true belief. The theory casts new light on such philosophical problems as scepticism, evidence, probability and assertion, realism and anti-realism, and the limits of what can be known. The arguments are (...) illustrated by rigorous models based on epistemic logic and probability theory. The result is a new way of doing epistemology and a notable contribution to the philosophy of mind. (shrink)

§I schematises the evidence for an understanding of ‘know’ and other terms of epistemic appraisal that embodies contextualism or subject-sensitive invariantism, and distinguishes between those two approaches. §II argues that although the cases for contextualism and sensitive invariantism rely on a principle of charity in the interpretation of epistemic claims, neither approach satisfies charity fully, since both attribute metalinguistic errors to speakers. §III provides an equally charitable anti-sceptical insensitive invariantist explanation of much of the same evidence as the result of (...) psychological bias caused by salience effects. §IV suggests that the explanation appears to have implausible consequences about practical reasoning, but also that applications of contextualism or sensitive invariantism to the problem of scepticism have such consequences. §V argues that the inevitable difference between appropriateness and knowledge of appropriateness in practical reasoning, closely related to the difference between knowledge and knowledge of knowledge, explains the apparent implausibility. (shrink)

Judging by our folk appraisals, then, knowledge and action are intimately related. The theories of rational action with which we are familiar leave this unexplained. Moreover, discussions of knowledge are frequently silent about this connection. This is a shame, since if there is such a connection it would seem to constitute one of the most fundamental roles for knowledge. Our purpose in this paper is to rectify this lacuna, by exploring ways in which knowing something is related to rationally acting (...) upon it, defending one particular proposal against anticipated objections. (shrink)

Newcomb's problem and similar cases show the need to incorporate causal distinctions into the theory of rational decision; the usual noncausal decision theory, though simpler, does not always give the right answers. I give my own version of causal decision theory, compare it with versions offered by several other authors, and suggest that the versions have more in common than meets the eye.

I shall be mainly concerned with the question ‘What is personal propositional knowledge?’. This question is obviously quite narrowly focused, in three respects. In the first place, there is impersonal as well as personal knowledge. Second, a distinction is often drawn between propositional knowledge and practical knowledge. And third, as well as asking what knowledge is, it is also possible to ask whether and how knowledge of various kinds can be acquired: causal knowledge, a priori knowledge, moral knowledge, and so (...) on. I shall dwell briefly on each of these three points. First, there is the distinction between personal and impersonal knowledge – in other words, between the psychological concept of knowledge and the social one.1 We use the concept of knowledge to describe the cognitive condition of individuals; but we also use it to describe the progress of scientific and historical research. So for example we can speak or enquire about the state of knowledge in a particular field of biology or history. And if we do so, we are evidently not concerned with what anyone in particular knows about, say, the genetics of fruit flies or the career of Charlemagne, but rather with what the scientific or academic community knows. Needless to say, there is a close connection between personal and impersonal knowledge. But ‘It is known that p’ does not simply mean ‘Someone or other. (shrink)

Evidentialism is the thesis that epistemic justification for belief supervenes on evidential support. However, we claim there are cases in which, even though two subjects have the same evidential support for a proposition, only one of them is justified. What make the difference are pragmatic factors, factors having to do with our cares and concerns. Our argument against evidentialism is not based on intuitions about particular cases. Rather, we aim to provide a theoretical basis for rejecting evidentialism by defending a (...) “pragmatic” necessary condition on epistemic justification. We argue for the following necessary condition for justification: S is justified in believing that p only if S is rational to prefer (and, hence, act) as if p. In light of this necessary condition, the price of evidentialism is skepticism, or something close to it. (shrink)

The core of Anthony Brueckner’s critique in ‘Knowledge, Evidence, and Skepticism according to Williamson’ is his claim in section 5 that my account of perceptual knowledge has an unacceptable consequence. My reply will concentrate on that claim and largely ignore the rest of Brueckner’s interesting discussion, for it is easy to check that the claim is essential to Brueckner’s argument against my analysis of skepticism and evidence.

Many economic problems are also ethical problems: should we value economic equality? how much should we care about preserving the environment? how should medical resources be divided between saving life and enhancing life? This book examines some of the practical issues that lie between economics and ethics, and shows how utility theory can contribute to ethics. John Broome's work has, unusually, combined sophisticated economic and philosophical expertise, and Ethics Out of Economics brings together some of his most important essays, augmented (...) with an updated introduction. The first group of essays deals with the relation between preference and value, the second with various questions about the formal structure of good, and the concluding section with the value of life. This work is of interest and importance for both economists and philosophers, and shows powerfully how economic methods can contribute to moral philosophy. (shrink)

The core of Tony Brueckner’s critique in ‘Knowledge, Evidence, and Skepticism according to Williamson’ is his claim in section 5 that my account of perceptual knowledge has an unacceptable consequence. My reply will concentrate on that claim and largely ignore the rest of Brueckner’s interesting discussion, for it is easy to check that the claim is essential to Brueckner’s argument against my analysis of skepticism and evidence.

Bayesians have traditionally taken a dim view of the Inference to the Best Explanation, arguing that, if IBE is at variance with Bayes ' rule, then it runs afoul of the dynamic Dutch book argument. More recently, Bayes ' rule has been claimed to be superior on grounds of conduciveness to our epistemic goal. The present paper aims to show that neither of these arguments succeeds in undermining IBE.