I defend a version of Kripke's claim that the metaphysically necessary and the knowable a priori are independent. On my version, there are two independent families of modal notions, metaphysical and epistemic, neither stronger than the other. Metaphysical possibility is constrained by the laws of nature. Logical validity, I suggest, is best understood in terms of epistemic necessity.

The traditional view that all logical truths are metaphysically necessary has come under attack in recent years. The contrary claim is prominent in David Kaplan’s work on demonstratives, and Edward Zalta has argued that logical truths that are not necessary appear in modal languages supplemented only with some device for making reference to the actual world (and thus independently of whether demonstratives like ‘I’, ‘here’, and ‘now’ are present). If this latter claim can be sustained, it strikes close to the (...) heart of the traditional view. I begin this paper by discussing and refuting Zalta’s argument in the context of a language for propositional modal logic with an actuality connective (section 1). This involves showing that his argument in favor of real world validity his preferred explication of logical truth, is fallacious. Next (section 2) I argue for an alternative explication of logical truth called general validity. Since the rule of necessitation preserves general validity, the argument of section 2 provides a reason for affirming the traditional view. Finally (section 3) I show that the intuitive idea behind the discredited notion of real world validity finds legitimate expression in an object language connective for deep necessity. (shrink)

In earlier work (Glüer, K. and P. Pagin. 2006. Proper names and relational modality. Linguistics & Philosophy 29: 507–35; Glüer, K. and P. Pagin. 2008. Relational modality. Journal of Logic, Language and Information 17: 307–22), we developed a semantics for (metaphysical) modal operators that accommodates Kripkean intuitions about proper names in modal contexts even if names are not rigid designators. Graeme Forbes (2011. The problem of factives for sense theories. Analysis 71: 654–62.) criticizes our proposal. He argues that our semantics (...) predicts readings for certain natural language sentences which these simply do not have. These sentences contain mixed contexts involving factive attitude verbs. We argue that the readings our semantics predicts do indeed exist, even if it might take a little work to bring them out. Moreover, denying their existence would have some rather unattractive consequences. (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)

When I say ‘Hesperus is Phosphorus’, I seem to express a proposition. And when I say ‘Joan believes that Hesperus is Phosphorus’, I seem to ascribe to Joan an attitude to the same proposition. But what are propositions? And what is involved in ascribing propositional attitudes?

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)

The book is an extended study of the problem of consciousness. After setting up the problem, I argue that reductive explanation of consciousness is impossible , and that if one takes consciousness seriously, one has to go beyond a strict materialist framework. In the second half of the book, I move toward a positive theory of consciousness with fundamental laws linking the physical and the experiential in a systematic way. Finally, I use the ideas and arguments developed earlier to defend (...) a form of strong artificial intelligence and to analyze some problems in the foundations of quantum mechanics. (shrink)

I defend a version of Kripke's claim that the metaphysically necessary and the knowable a priori are independent. On my version, there are two independent families of modal notions, metaphysical and epistemic, neither stronger than the other. Metaphysical possibility is constrained by the laws of nature. Logical validity, I suggest, is best understood in terms of epistemic necessity.

The two-dimensional modal logic of Davies and Humberstone [3] is an important aid to our understanding the relationship between actuality, necessity and a priori knowability. I show how a cut-free hypersequent calculus for 2D modal logic not only captures the logic precisely, but may be used to address issues in the epistemology and metaphysics of our modal concepts. I will explain how the use of our concepts motivates the inference rules of the sequent calculus, and then show that the completeness (...) of the calculus for Davies–Humberstone models explains why those concepts have the structure described by those models. The result is yet another application of the completeness theorem. (shrink)

Can some contingent truths be known a priori?: when this question is raised in modern philosophy — as, following Kripke, it often has been — it generally introduces a discussion of certain examples which seem to turn on indexical or indexical-like words . Sometimes the indexicality is quite obvious, as in 'I am here now', sometimes it appears only on analysis, as in 'If anyone uniquely invented the zip, Julius did', where by stipulation 'Julius' rigidly designates the inventor of the (...) zip , for the rigidity of 'Julius' can be expressed by means of the 'actually' operator, which is at least formally analogous to an indexical . Moreover, this indexicality has been exploited in a well known argument that what is known a priori can be contingent only in a superficial way pp. 161-89; technical details are omitted, since deep and superficial contingency coincide for sentences, such as those considered below, without 'actually' or similar operators). The purpose of this note is to argue that there are deeply contingent a priori truths which in no way turn on indexicals. I do not deny that there are also contingent a priori truths which do turn on indexicals, but we are unlikely to get clear on the contingent a priori in-general if we take it to be essentially tied up with indexicals when in fact it is not. (shrink)

This paper criticizes Soames’s main argument against a variant of two-dimensionalism that he calls strong two-dimensionalism. The idea of Soames’s argument is to show that the strong two-dimensionalist’s semantics for belief ascriptions delivers wrong semantic verdicts about certain complex modal sentences that contain both such ascriptions and claims about the truth of the ascribed beliefs. A closer look at the formal semantics underlying strong two-dimensionalism reveals that there are two feasible ways of specifying the truth conditions for claims of the (...) latter sort. Only one of the two yields the problematic semantic verdicts, so strong two-dimensionalists can avoid Soames’s argument by settling for the other way. (shrink)

Saul Kripke's thesis that ordinary proper names are rigid designators is supported by widely shared intuitions about the occurrence of names in ordinary modal contexts. By those intuitions names are scopeless with respect to the modal expressions. That is, sentences in a pair like (a) Aristotle might have been fond of dogs, (b) Concerning Aristotle, it is true that he might have been fond of dogs will have the same truth value. The same does not in general hold for definite (...) descriptions. If one, like Kripke, accounts for this difference by means of the intensions of the names and the descriptions, the conclusion is that names do not in general have the same intension as any normal, identifying description. However, this difference can be accounted for alternatively by appeal to the semantics of the modal expressions. On the account we suggest, dubbed 'relational modality', simple singular terms, like proper names, contribute to modal contexts simply by their actual world reference, not by their descriptive content. That account turns out to be fully equivalent with the rigidity account when it comes to truth of modal and non-modal sentence (with respect to the actual world), and hence supports the same basic intuitions. Here we present the relational modality account and compare it with others, in particular Kripke's own. (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.

In this book, Scott Soames defends the revolution in philosophy led by Saul Kripke, Hilary Putnam, and David Kaplan against attack from those wishing to revive ..

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.

What are the objects of knowledge, belief, probability, apriority or analyticity? For at least some of these properties, it seems plausible that the objects are sentences, or sentence-like entities. However, results from mathematical logic indicate that sentential properties are subject to severe formal limitations. After surveying these results, I argue that they are more problematic than often assumed, that they can be avoided by taking the objects of the relevant property to be coarse-grained (“sets of worlds”) propositions, and that all (...) this has little to do with the choice between operators and predicates. (shrink)

This paper discusses some recent responses to Kripke’s modal objections to descriptivism about names. One response, due to Gluer-Pagin and Pagin, involves employing "actually" operators in a new way. Another, developed mainly by Chalmers, involves distinguishing the dimension of meaning modal operators affect from the dimension other operators, especially epistemic ones, affect. I argue that both these moves run into problems with "mixed" contexts involving factive verbs such as "know", "establish", "prove", etc. In mixed contexts there are both modal and (...) epistemic operators, and it seems that some contradictory examples, such as "possibly (Hesperus has a moon and someone establishes that Hesperus has no moon)", are classified as true according to these views. (shrink)

It is widely believed that for all p, or at least for all entertainable p, it is knowable a priori that (p iff actually p). It is even more widely believed that for all such p, it is knowable that (p iff actually p). There is a simple argument against these claims from four antecedently plausible premises.

Two-dimensional (2D) semantics is a formal framework that is used to characterize the meaning of certain linguistic expressions and the entailment relations among sentences containing them. 2D semantics has also been applied to thought contents. In contrast with standard possible worlds semantics, 2D semantics assigns extensions and truth-values to expressions relative to two possible world parameters, rather than just one. So a 2D semantic framework provides finer-grained semantic values than those available within standard possible world semantics, while using the same (...) basic model-theoretic resources. The 2D framework itself is just a formal tool. To develop a semantic theory for someone’s language, a proponent of 2D semantics must do three things: (i) explain what exactly the two possible world parameters represent, (ii) explain the rules for assigning 2D semantic values to a person’s words and sentences, and (iii) explain how 2D semantic values help in understanding the meanings of the person’s words and sentences. (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)