Online research in philosophy

[Robert Stalnaker] Saul Kripke made a convincing case that there are necessary truths that are knowable only a posteriori as well as contingent truths that are knowable a priori. A number of philosophers have used a two-dimensional model semantic apparatus to represent and clarify the phenomena that Kripke pointed to. According to this analysis, statements have truth-conditions in two different ways depending on whether one considers a possible world 'as actual' or 'as counterfactual' in determining the truth-value of the statement relative to that possible world. There are no necessary a posteriori or contingent a priori propositions: rather, contingent a priori and necessary a posteriori statements are statements that are necessary when evaluated one way, and contingent when evaluated the other way. This paper distinguishes two ways that the two-dimensional framework can be interpreted, and argues that one of them gives the better account of what it means to 'consider a world as actual', but that it provides no support for any notion of purely conceptual a priori truth. /// [Thomas Baldwin] Two-dimensional possible world semantic theory suggests that Kripke's examples of the necessary a posteriori and contingent a priori should be handled by interpreting names as implicitly indexical. Like Stalnaker, I reject this account of names and accept that Kripke's examples have to be accommodated within a metasemantic theory. But whereas Stalnaker maintains that a metasemantic approach undermines the conception of a priori truth, I argue that it offers the opportunity to develop a conception of the a priori aspect of stipulations, conceived as linguistic performances. The resulting position accommodates Kripke's examples in a way which is both intrinsically plausible and fits with Kripke's actual discussion of them.

[Robert Stalnaker] Saul Kripke made a convincing case that there are necessary truths that are knowable only a posteriori as well as contingent truths that are knowable a priori. A number of philosophers have used a two-dimensional model semantic apparatus to represent and clarify the phenomena that Kripke pointed to. According to this analysis, statements have truth-conditions in two different ways depending on whether one considers a possible world 'as actual' or 'as counterfactual' in determining the truth-value of the statement relative to that possible world. There are no necessary a posteriori or contingent a priori propositions: rather, contingent a priori and necessary a posteriori statements are statements that are necessary when evaluated one way, and contingent when evaluated the other way. This paper distinguishes two ways that the two-dimensional framework can be interpreted, and argues that one of them gives the better account of what it means to 'consider a world as actual', but that it provides no support for any notion of purely conceptual a priori truth. /// [Thomas Baldwin] Two-dimensional possible world semantic theory suggests that Kripke's examples of the necessary a posteriori and contingent a priori should be handled by interpreting names as implicitly indexical. Like Stalnaker, I reject this account of names and accept that Kripke's examples have to be accommodated within a metasemantic theory. But whereas Stalnaker maintains that a metasemantic approach undermines the conception of a priori truth, I argue that it offers the opportunity to develop a conception of the a priori aspect of stipulations, conceived as linguistic performances. The resulting position accommodates Kripke's examples in a way which is both intrinsically plausible and fits with Kripke's actual discussion of them.

This paper outlines how we may understand knowing-that as a kind of knowing-how-to, and thereby as an ability. (Contrast this form of analysis with the more commonly attempted reduction, of knowing-how-to to knowing-that.) The sort of ability in question has much potential complexity. In general, questioning can, but need not, be part of this complexity. However, questioning is always an element in the complexity that is philosophical knowing. The paper comments on the nature of this particular form of knowing.

It is widely held that the meaning of certain types of terms, such as natural kind terms, is individuated externalistically, in terms of the individual's external environment. Recently a more radical thesis has emerged, a thesis we dub 'a posteriori semantics.' The suggestion is that not only does a term's meaning depend on the external environment, but so does its semantics. One motivation for this is the aim to account for cases where a putative natural kind term fails to pick out a natural kind: The term may have a standard externalist semantics (if it picks out a natural kind) or a more descriptivist one (if it does not). Knowing which semantics applies will therefore require detailed empirical knowledge. This move has also been employed in cases where a singular term, such as a name, fails to have a reference. We argue that a posteriori semantics is inherently implausible, since the type of semantics common terms should be given ought not to be conditional on details of chemistry or physics. A number of difficulties for the position—'metaphysical,' epistemological, and methodological—are articulated. Finally, we suggest that a posteriori semantics misconstrues the way in which semantics is empirical.

Chalmers and Jackson (2001) offer an epistemic interpretation of the two-dimensional semantic framework advanced by Kaplan (1979, 1989), Stalnaker (1978), and others. Epistemic two-dimensional semantics (E2D) aims to re-forge the link between necessity and a priority seemingly broken by Kripke (1972/1980). On the E2D strategy, a priori knowledge of certain semantic intensions provides a route to a priori knowledge of a wide range of modal truths---nice outcome, if we can get it. E2D faces the serious challenge, however, that we typically don't have even in-principle a priori access to the intensions at issue (Byrne and Pryor 2006, Melnyk 2001; see also Wilson 1982). As we substantiate, the "access-based challenge" to Chalmers and Jackson's version of E2D is successful; but the problem here isn't for E2D per se, but rather to E2D interpreted as appealing to a conceiving-based epistemology of intensions. Here we develop a version of E2D appealing to abduction rather than conceivability. We argue that abduction gives rise to beliefs that are reasonably taken to be a priori; and we show that E2D when combined with an abductive epistemology of intensions---that is, abductive two-dimensionalism---can successfully respond to the access-based challenge. We finish up with a case study, involving zombies and the mind-body problem, illustrating how the two versions of E2D may differ in application.

Robert Stalnaker is an actualist who holds that merely possible worlds are uninstantiated properties that might have been instantiated. Stalnaker also holds that there are no metaphysically impossible worlds: uninstantiated properties that couldn't have been instantiated. These views motivate Stalnaker's "two dimensional" account of the necessary a posteriori on which there is no single proposition that is both necessary and a posteriori. For a (metaphysically) necessary proposition is true in all (metaphysically) possible worlds. If there were necessary a posteriori propositions, that would mean that there were propositions true in all possible worlds but which could only be known to be true by acquiring empirical evidence. Consider such a purported proposition P. The role of empirical evidence for establishing P's truth would have to be to rule out worlds in which P is false. If there were no such worlds to be ruled out, we would not require evidence for P. But by hypothesis, P is necessary and so true in all metaphysically possible worlds. And on Stalnaker's view, the metaphysically possible worlds are all the worlds there are. So there can be no proposition that is true in all possible worlds, but that we require evidence to know. In this way, the motivation for Stalnaker's two dimensional account of the necessary a posteriori rests on his denying that there are metaphysically impossible Worlds. I argue that given his view of what possible worlds are, Stalnaker has no principled reason for denying that there are metaphysically impossible worlds. If I am right, this undercuts Stalnaker's motivation for his two dimensional account of the necessary a posteriori.

The essence of the associated-proposition strategy is to distinguish the necessary proposition _expressed by_ a sentence.

_the a priori role_ (for word T). For instance, perhaps anyone who understands the word _water_ is able to know, without appeal to any further a posteriori information, that _water_ refers to the clear, drinkable natural kind whose instances are predominant in our oceans and lakes (if _water_ refers at all.