Two-dimensional semantics aims to eliminate the puzzle of necessary a posteriori and contingent a priori truths. Recently many argue that even assuming two-dimensional semantics we are left with the puzzle of necessary and a posteriori propositions. Stephen Yablo (Pacific Philosophical Quarterly, 81, 98–122, 2000) and Penelope Mackie (Analysis, 62(3), 225–236, 2002) argue that a plausible sense of “knowing which” lets us know the object of such a proposition, and yet its necessity is “hidden” and thus a posteriori. This paper answers (...) this objection; I argue that given two-dimensional semantics you cannot know a necessary proposition without knowing that it is true. (shrink)

I. Standard Semantics According to what we might call.

_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.

Here the extension of a sentence token is a truth-value, the extension of a name is an individual, and so on. Scenarios are most often understood as centered possible worlds – i.e. ordered triples of worlds, individuals, and times - although they may also be understood in other ways.

A number of popular arguments for dualism start from a premise about an epistemic gap between physical truths about truths about consciousness, and infer an ontological gap between physical processes and consciousness. Arguments of this sort include the conceivability argument, the knowledge argument, the explanatory-gap argument, and the property dualism argument. Such arguments are often resisted on the grounds that epistemic premises do not entail ontological conclusion. My view is that one can legitimately infer ontological conclusions from epistemic premises, if (...) one is very careful about how one reasons. To do so, the best way is to reason first from epistemic premises to modal conclusions (about necessity and possibility), and from there to ontological conclusions. Here, the crucial issue is the link between the epistemic and modal domains. How can one reason from theses about what is knowable or conceivable to theses about what is necessary or possible? To bridge the epistemic and modal domains, the framework of two-dimensional semantics can play a central role. I have used this framework in earlier work (Chalmers 1996) to mount an argument against materialism. Here, I want to revisit the argument, laying it out in a more explicit and careful form, and responding to a number of objections. In what follows I will concentrate mostly on the conceivability argument. I think that very similar considerations apply to the other arguments mentioned above, however. In the final section of the paper, I show how this analysis might yield a unified treatment of a number of anti-materialist arguments. (shrink)

At the April 2006 meeting of the Central Division of the American Philosophical Association, in an author-meets-critics session on Scott Soames' book _Reference and Description: The Case Against Two-Dimensionalism_ , I presented a comment on Soames' book, "Scott Soames' Two-Dimensionalism" . The other critic was Robert Stalnaker. Soames presented his response to critics . Below is a reply to Soames' response to me, for those who were at the session and interested others. Note that this response was mostly written before (...) the session, except for one or two paragraphs where the discussion in the session is mentioned. (shrink)

Why is two-dimensional semantics important? One can think of it as the most recent act in a drama involving three of the central concepts of philosophy: meaning, reason, and modality. First, Kant linked reason and modality, by suggesting that what is necessary is knowable a priori, and vice versa. Second, Frege linked reason and meaning, by proposing an aspect of meaning (sense) that is constitutively tied to cognitive signi?cance. Third, Carnap linked meaning and modality, by proposing an aspect of meaning (...) (intension) that is constitutively tied to possibility and necessity. (shrink)

Two-dimensional approaches to semantics, broadly understood, recognize two "dimensions" of the meaning or content of linguistic items. On these approaches, expressions and their utterances are associated with two different sorts of semantic values, which play different explanatory roles. Typically, one semantic value is associated with reference and ordinary truth-conditions, while the other is associated with the way that reference and truth-conditions depend on the external world. The second sort of semantic value is often held to play a distinctive role in (...) analyzing matters of cognitive significance and/or context-dependence. (shrink)

What is involved in the meaning of our expressions? Frege suggested that there is an aspect of an expression.

Reliabilism about epistemic justification – thethesis that what makes a belief epistemicallyjustified is that it was produced by a reliableprocess of belief-formation – must face twoproblems. First, what has been called ``the newevil demon problem'', which arises from the ideathat the beliefs of victims of an evil demonare as justified as our own beliefs, althoughthey are not – the objector claims – reliablyproduced. And second, the problem of diagnosingwhy skepticism is so appealing despite beingfalse. I present a special version ofreliabilism, (...) ``indexical reliabilism'', based ontwo-dimensional semantics, and show how it cansolve both problems. (shrink)

As tends to be the way with philosophical positions, there are at least as many two-dimensionalisms as there are two-dimensionalists. But painting with a broad brush, there are core epistemological and metaphysical commitments which underlie the two-dimensionalist project, commitments for which I have no sympathies. A sketch of three signi?cant points of disagreement.

Two-dimensional semantics is a framework that helps us better understand some of the most fundamental issues in philosophy: those having to do with the relationship between the meaning of words, the way the world is, and our knowledge of the meaning of words. This selection of new essays by some of the world's leading authorities in this field sheds fresh light both on foundational issues regarding two-dimensional semantics and on its specific applications. Contributors: Richard Breheny, Alex Byrne, David Chalmers, Martin (...) Davies, Gareth Evans, Manuel Garcia-Carpintero, Josep Maci`, Martine Nida-Rumelin, Christopher Peacocke, James Pryor, Francois Recanati, Scott Soames, Cara Spencer, Robert Stalnaker, Kai-Yee Wong, Stephen Yablo. (shrink)

Abstract: In recent years two-dimensional semantics has become one of the most serious alternatives to Millianism for the proper interpretation of modal discourse. It has origins in the works of a diverse group of philosophers, and it has proven popular as an interpretation of both language and thought. It has probably received most of its attention, however, because of its use by David Chalmers in his arguments against materialism. It is this more metaphysical application of two-dimensionalism that is the concern (...) in this paper. For though there is probably something salvageable from two-dimensionalism as a way to explain the content of thought, as a metaphysical tool it should be abandoned. In this paper I aim to establish this point by reductio: if 'metaphysical' two-dimensionalism is assumed, it can be shown to be false. (shrink)

This paper recalls some applications of two-dimensional modal logic from the 1980s, including work on the logic of Actually and on a somewhat idealized version of the indicative/subjunctive distinction, as well as on absolute and relative necessity. There is some discussion of reactions this material has aroused in commentators since. We also survey related work by Leslie Tharp from roughly the same period.

. David Chalmerss version of two-dimensional semantics is an attempt at setting up a unified semantic framework that would vindicate both the Fregean and the Kripkean semantic intuitions. I claim that there are three acceptable ways of carrying out such a project, and that Chalmerss theory does not coherently fit any of the three patterns. I suggest that the theory may be seen as pointing to the possibility of a double reading for many linguistic expressions (a double reading which, however, (...) is not easily identified with straightforward semantic ambiguity). (shrink)

Hilary Putnam once proposed a semantic approach to, as well as a deflationist resolution of, the problem of analyticity. I take up and defend both ideas. First of all, I defend Putnam's semantic construal of the issue against Quine's reductive understanding. Secondly, I devise a semantics that successfully explains the genesis of the relevant analytic truths and that shows them to be harmless. Finally, I rebut the aspirations of the neo-descriptivist semantics, prominently propounded by David Chalmers and Frank Jackson, that (...) is widely presumed to spearhead the re-establishment of substantial analyticities. I conclude that analytic truths—at least those discussed—are indeed harmless. (shrink)

There are different _kinds _of two-dimensional matrix one can work with, representing different properties of an expression. One has to understand the rows and columns differently for the different matrices; but there are some formal characteristics all the matrices have in common.

Based on some of Kent Bach's work and Mount (2008), I point out certain shortcomings of parameter-based semantic two-dimensionalism for the modeling of indexicals and suggest to model context dependence on the basis of the assumptions of indidivual speakers, their rich background knowledge, and defeasible reasoning in a broadly-conceived Stalnakerian framework.

This paper argues that David Chalmer's new epistemic interpretation of 2-D semantics faces the very same type of objection he takes to defeat earlier contextualist interpretation of the 2-D framework.

In Epistemic Two-Dimensional Semantics, David Chalmers seeks to develop a version of 2-D semantics which can vindicate the rationalist claim that there are constitutive connections between meaning, possibility and a priority. Chalmers lays out different ways of filling in his preferred epistemic approach to 2-D semantics so as to avoid controversial philosophical assumptions. In these comments, however, I argue that there are some distinctively rationalist commitments in Chalmers's epistemic approach to 2-D semantics. I start by explaining why Chalmers's approach requires (...) a canonical language that affords subjects accurate a priori access to the space of possibility. I then argue that traditional worries about rationalism will simply re-emerge as worries about whether there can be a canonical vocabulary and how we could come to recognize one if there were. The moral is that Chalmers's 2-D semantic framework builds in substantive metaphysical and epistemological commitments which stand in need of further defense. (shrink)

Frank Jackson and David Chalmers have suggested that the diagonal intensions defined by their two-dimensional framework can play the two key roles of Fregean senses: they provide a priori accessible extension conditions for a representation and they provide the identity conditions for meanings and thought contents. In this paper, I clarify the nature of the psychological abilities that are needed to underwrite the first role. I then argue that these psychological abilities are not sufficiently stable or cognitively salient to individuate (...) meanings or thought contents. (shrink)

One of Kripke's fundamental objections to descriptivism was that the theory misclassifies certain a posteriori propositions expressed by sentences involving names as a priori. Though nowadays very few philosophers would endorse a descriptivism of the sort that Kripke criticized, many find two-dimensionalism attractive as a kind of successor theory. Because two-dimensionalism needn't be a form of descriptivism, it is not open to the epistemic argument as formulated by Kripke; but the most promising versions of two-dimensionalism are open to a close (...) relative of that argument. (shrink)

There is reason to expect a reasonable account of a priori knowledge to be linked with an account of the nature of conceptual thought. Recent “two-dimensionalist” accounts of conceptual thought propose an extremely direct connection between the two: on such views, being in a position to know a priori a large number of non-trivial propositions is a necessary condition of concept-possession. In this paper I criticize this view, by arguing that it requires an implausibly internalist and intellectualist conception of capacities (...) we bring to bear in applying concepts in experience. Empirical concept-application depends on the exercise of a variety of capacities, many of which can be grouped together under the general label “recognitional”. As I argue, two-dimensionalism cannot accommodate a plausible account of such capacities. This suggests that the link between a priori knowledge and the nature of conceptual thought is not as direct as twodimensionalists take it to be. I close by briefly sketching a different way to think of that link. (shrink)

Our primary interest this week will be in two objections Jackson mentions which seem to threaten his program. Each of them is avoided by appeal to the two-dimensional framework we sketched last week. Before we go over that framework again, we will start by looking at the objections. For reasons that may become apparent shortly, we will look at them in reverse order. So first we’ll look at this objection from Chapter 3, an objection which turns on the discovery of (...) a posteriori necessities by Kripke and Putnam. (shrink)

Applying two-dimensional modal semantics, some philosophers, most recently Frank Jackson and David Chalmers among others, have sought to provide analyses of Kripke’s examples of the necessary a posteriori. Despite the massive amount of attention that two-dimensionalism has received of late, Robert Nozick’s recent accounting of Kripke’s examples, which bears striking similarities to these two-dimensionalist analyses but reached a different conclusion, has gone unnoticed. This paper argues that (a) underlying such a difference is a serious problem with the two-dimensionalist approach to (...) the necessary a posteriori and (b) thinking through this problem will go a long way towards a proper understanding, and thus assessment, of this approach. (shrink)

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