The simplest story about modals—might, must, possibly, necessary, have to, can, ought to, presumably, likelier, and the rest—is also the canon: modals are context-dependent quantifiers over a domain of possibilities. Different flavors of modality correspond to quantification over different domains of possibilities. Logical modalities quantify over all the possibilities there are, physical modalities over possibilities compatible with the..

Knowledge and Lotteries is organized around an epistemological puzzle: in many cases, we seem consistently inclined to deny that we know a certain class of propositions, while crediting ourselves with knowledge of propositions that imply them. In its starkest form, the puzzle is this: we do not think we know that a given lottery ticket will be a loser, yet we normally count ourselves as knowing all sorts of ordinary things that entail that its holder will not suddenly acquire a (...) large fortune. After providing a number of specific and general characterizations of the puzzle, Hawthorne carefully examines the competing merits of candidate solutions. In so doing, he explores a number of central questions concerning the nature and importance of knowledge, including the relationship of knowledge to assertion and practical reasoning, the status of epistemic closure principles, the merits of various brands of scepticism, the prospects for a contextualist account of knowledge, and the potential for other sorts of salience-sensitive accounts. Along the way, he offers a careful treatment of pertinent issues at the foundations of semantics. His book will be of interest to anyone working in the field of epistemology, as well as to philosophers of language. (shrink)

Concessive knowledge attributions (CKAs) are knowledge attributions of the form ‘S knows p, but it’s possible that q’, where q obviously entails not-p (Rysiew, Nous (Detroit, Mich.) 35:477–514, 2001). The significance of CKAs has been widely discussed recently. It’s agreed by all that CKAs are infelicitous, at least typically. But the agreement ends there. Different writers have invoked them in their defenses of all sorts of philosophical theses; to name just a few: contextualism, invariantism, fallibilism, infallibilism, and that the knowledge (...) rules for assertion and practical reasoning are false. In fact, there is a lot of confusion about CKAs and their significance. I try to clear some of this confusion up, as well as show what their significance is with respect to the debate between fallibilists and infallibilists about knowledge in particular. (shrink)

By “epistemic modals,” I mean epistemic uses of modal words: adverbs like “necessarily,” “possibly,” and “probably,” adjectives like “necessary,” “possible,” and “probable,” and auxiliaries like “might,” “may,” “must,” and “could.” It is hard to say exactly what makes a word modal, or what makes a use of a modal epistemic, without begging the questions that will be our concern below, but some examples should get the idea across. If I say “Goldbach’s conjecture might be true, and it might be false,” (...) I am not endorsing the Cartesian view that God could have made the truths of arithmetic come out differently. I make the claim not because I believe in the metaphysical contingency of mathematics, but because I know that Goldbach’s conjecture has not yet been proved or refuted. Similarly, if I say “Joe can’t be running,” I am not saying that Joe’s constitution prohibits him from running, or that Joe is essentially a non-runner, or that Joe isn’t allowed to run. My basis for making the claim may be nothing more than that I see Joe’s running shoes hanging on a hook. (shrink)

Epistemic modals are standardly taken to be context-dependent quantifiers over possibilities. Thus sentences containing them get truth-values with respect to both a context and an index. But some insist that this relativization is not relative enough: `might'-claims, they say, only get truth-values with respect to contexts, indices, and—the new wrinkle—points of assessment (hence, CIA). Here we argue against such "relativist" semantics. We begin with a sketch of the motivation for such theories and a generic formulation of them. Then we catalogue (...) central problems that any such theory faces. We end by outlining an alternative story. (shrink)

David Lewis (1941-2001) was Class of 1943 University Professor of Philosophy at Princeton University. His contributions spanned philosophical logic, philosophy of language, philosophy of mind, philosophy of science, metaphysics, and epistemology. In On the Plurality of Worlds, he defended his challenging metaphysical position, "modal realism." He was also the author of the books Convention, Counterfactuals, Parts of Classes, and several volumes of collected papers.

I think that there are good reasons to adopt a relativist semantics for epistemic modal claims such as ``the treasure might be under the palm tree'', according to which such utterances determine a truth value relative to something finer-grained than just a world (or a <world, time> pair). Anyone who is inclined to relativise truth to more than just worlds and times faces a problem about assertion. It's easy to be puzzled about just what purpose would be served by assertions (...) of this kind, and how to understand what we'd be up to in our use of sentences like ``the treasure might be under the palm tree'', if they have such peculiar truth conditions. After providing a very quick argument to motivate a relativist view of epistemic modals, I bring out and attempt to resolve this problem in making sense of the role of assertions with relativist truth conditions. Solving this problem should be helpful in two ways: first, it eliminates an apparently forceful objection to relativism, and second, spelling out the relativist account of assertion and communication will help to make clear just what the relativist position is, exactly, and why it's interesting. (shrink)

Lewis concludes that fallibilism is uncomfortable, though preferable to scepticism. However, he believes that contextualism about knowledge allows us to ‘dodge the choice’ between fallibilism and scepticism. For the contextualist semantics for ‘know’ can explain the oddity of fallibilism, without landing us into scepticism.

Fallibilism in epistemology is neither identical to nor unrelated to the ordinary notion of fallibility. In ordinary life we are forced to the conclusion that human beings are prone to error. The epistemological doctrine of fallibilism, though, is about the consistency of holding that humans have knowledge while admitting certain limitations in human ways of knowing. As will be seen, making the content of the basic intuition more precise is both somewhat contentious and the key to an adequate definition of (...) fallibilism. Before moving on to this project I will address a few preliminary issues. Then, after canvassing some prevailing views I will address two concerns. First, I will address the concern that prevailing views do not adequately take into account fallible knowledge of necessary truths and are thus not fully general accounts of fallible knowledge. Second, I will address probabilistic accounts of fallibilism. I will suggest that a simple, adequate account of fallibilism is possible. (shrink)

Claims of the form 'I know P and it might be that not-P' tend to sound odd. One natural explanation of this oddity is that the conjuncts are semantically incompatible: in its core epistemic use, 'Might P' is true in a speaker's mouth only if the speaker does not know that not-P. In this paper I defend this view against an alternative proposal that has been advocated by Trent Dougherty and Patrick Rysiew and elaborated upon in Jeremy Fantl and Matthew (...) McGrath's recent Knowledge in an Uncertain World. (shrink)

way on the information available in the contexts in which they are used, it’s not surprising that there is a minor but growing industry of work in semantics and the philosophy of language concerned with the precise nature of the context-dependency of epistemically modalized sentences. Take, for instance, an epistemic might-claim like..

If knowing requires believing on the basis of evidence that entails what’s believed, we have hardly any knowledge at all. Hence the near-universal acceptance of fallibilism in epistemology: if it's true that "we are all fallibilists now" (Siegel 1997: 164), that's because denying that one can know on the basis of non-entailing evidence1is, it seems, not an option if we're to preserve the very strong appearance that we do know many things (Cohen 1988: 91). Hence the significance of concessive knowledge (...) attributions (CKAs) (Rysiew 2001)—i.e., sentences of the form 'S knows that p, but it's possible that q' (where q entails not-p). To many, utterances of such sentences sound very odd indeed. According to David Lewis (1996: 550), however, such sentences are merely "overt, explicit" statements of fallibilism; if so, their seeming incoherence suggests that, contrary to our everyday epistemic pretensions, "knowledge must be by definition infallible" after all (ibid.: 549). -/- Recently Jason Stanley (2005) has defended fallibilism against the Lewisian worry that overtly fallibilistic speech is incoherent. According yo Stanley, CKAs are not just odd-sounding: in most cases, they are simply false. But this doesn't impugn fallibilism. Insofar as the odd-sounding utterances Lewis cites state the fallibilist idea, the latter portion thereof ('S cannot eliminate a certain possibility in which not-p', e.g.) expresses the idea that the subject's evidence doesn't entail what's (allegedly) known (hence, the negation of any contrary propositions). According to Stanley, however, this is not the best reading of the possibility clauses CKAs contain. On the correct account of the latter, while the sentences Lewis cites are almost always self-contradictory, they don't capture the fallibilist idea after all. Here, we argue that the sentences in question do express precisely the fallibilist idea, but argue that Lewis has nonetheless failed to raise a problem for the latter. In addition, we respond to worries that the resulting view of the semantics of epistemic possibility statements has certain unacceptable consequences. (shrink)

In a recent article Dylan Dodd has argued that anyone who holds that all knowledge is evidence must concede that we know next to nothing about die external world. The argument is intended to show that any infallibilist account of knowledge is committed to scepticism, and that anyone who identifies our evidence with the propositions we know is committed to infallibilism. I shall offer some reasons for thinking Dodd's argument is unsound, and explain where his argument goes wrong.

Almost every contemporary theory of knowledge is a version of fallibilism, yet an adequate statement of fallibilism has not yet been provided. Standard definitions cannot account for fallibilistic knowledge of necessary truths. I consider and reject several attempts to resolve this difficulty before arguing that a belief is an instance of fallibilistic knowledge when it could have failed to be knowledge. This is a fully general account of fallibilism that applies to knowledge of necessary truths. Moreover, it reveals, not only (...) the connection between fallibility and error, but the connection between fallibility and accidental truth as well. (shrink)

are ambiguous. In the mouth of someone who cannot remember whether it was Michael, or rather someone else, who was top scorer, can express the epistemic possibility that Michael led the league in scoring. But from someone who knows that Michael did not even play last season, but is wondering what would have happened if he had, means something quite different. Now where it has this quite different meaning, may still turn out to be the expression of some epistemic possibility. (...) Perhaps where does not express the epistemic possibility of ‘Michael led the league in scoring’, it expresses the epistemic possibility of ‘Michael would have led the league in scoring’. Analysis of this ‘would have’ statement, together with an exploration of the suspicion that the ‘might have’ statement is ambiguous between these two epistemic possibilities, will have to await another occasion. The important point for present purposes is that is ambiguous between an expression of the epistemic possibility of ‘Michael led the league in scoring’ and some quite different reading. (shrink)