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In his writings on philosophical logic, Gottlob Frege distinguished between two semantic factors that, he thought, are associated with any fully meaningful expression.1 The first of these is the expression's reference (Bedeutung); philosophers and linguists now have a good understanding of how the reference of many a complex expression depends on the references of its parts. But Frege also held that any meaningful expression has a sense (Sinn), and that two expressions may differ in sense while sharing a reference (see Frege 1892, 25-27). The project of saying how the sense of a complex expression relates to the senses of its parts is less advanced, and pessimism about the prospect of carrying it to a successful conclusion is a source of doubt whether expressions possess senses whose identities are not fixed by their references, notwithstanding Frege 's arguments and examples. In this essay, I construct a compositional theory of senses for a small but nontrivial fragment of a natural language. I thereby hope to vindicate the thesis that a satisfactory semantic theory should treat of intensional as well as extensional elements against a corrosive source of scepticism.1. Problems in Accommodating SenseSome popular frameworks for semantic theory provide no houseroom for senses. Each "name of a truth-value" - the closest correlate to a complete statement in Frege 's formalized language2 - "expresses a sense, a thought. Namely, by our stipulations it is determined under what conditions the name denotes the True. The sense of this name - the thought - is the thought that these conditions are fulfilled" (Frege 1893, §32, 50). This famous passage from Grundgesetze suggests that a statement's sense may be identified with its trum-conditions, but a popular account of truth-conditions makes the identification impossible to sustain. According to that account, a statement's truth-conditions are given by the possible worlds, or possible circumstances, at which it is true; 'possible' means 'metaphysically possible'.3 This account, however, immediately generates a problem for a Fregean. Let us imagine a context in which it is not common knowledge - perhaps because it is not known at all - that the names 'Hesperus' and 'Phosphorus' share a reference. Frege would certainly maintain that the statements 'Hesperus is bright' and 'Phosphorus is bright', as used in such a context, differ in sense. Since Kripke's Naming and Necessity (1980), however, most philosophers have come to accept that it is metaphysically necessary that Hesperus is identical with Phosphorus, so that any metaphysically possible world, or metaphysically possible circumstance, at which one statement is true is a world or circumstance at which the other is true. That is to say, the familiar modal gloss on the notion of a truth-condition fails to accommodate a key thesis of Frege's about sense.Another familiar gloss on that notion faces a different problem. Some philosophers take a statement's truth-conditions to be given by its canonical T-theorem in an interpretative truth-theory for the language to which the statement belongs. (See Wiggins 1976 and McDowell 1977.) It is then argued that the difference in sense between our two statements is shown by the fact that the pair of T-sentences(HB) 'Hesperus is bright' is true if and only if Hesperus is bright and(PB) 'Phosphorus is bright' is true if and only if Phosphorus is brightare theorems of a truth-theory that is interpretative for the speakers in the imagined context, whilst the pairs(HB!) 'Hesperus is bright' is true if and only if Venus is bright and(PB,) 'Phosphorus is bright' is true if and only if Venus is bright and for that matter(HB2) 'Hesperus is bright' is true if and only if Phosphorus is brightand(PB2) 'Phosphorus is bright' is true if and only if Hesperus is brightare not interpretative for those speakers.4 The different status of these Tsentences reflects the fact that the pair of reference assignments(H) 'Hesperus' refers to Hesperusand(P) 'Phosphorus' refers to Phosphoruscan serve as axioms of an interpretative truth-theory, whilst the pairs(H,) 'Hesperus' refers to Venusand(P,) 'Phosphorus' refers to Venusand for that matter(H2) 'Hesperus' refers to Phosphorusand(P2) 'Phosphorus' refers to Hesperuscannot so serve. …

Church, A. 2009. Referee reports on Fitch's 'A definition of value'. In New Essays on the Knowability Paradox, ed. J. Salerno, 13-20. Oxford: Oxford University Press. Dummett, M. 1975. Wang's paradox. Synthese 30: 301-4. Dummett, M. 1978. Truth and Other Enigmas. London: Duckworth. Dummett, M. 1994. Reply to Prawitz. In The Philosophy of Michael Dummett, eds. D. Prawitz and G. Olivieri, 292-99. Dordrecht: Kluwer. Dummett, M. 2001. Victor's error. Analysis 61: 1-2. Dummett, M. 2007. Reply to Wolfgang Kiinne. In The Philosophy of Michael Dummett, eds. R.E. Auxier and L.E. Hahn, 345-50. Chicago: Open Court. Edgington, D. 1985. The paradox of knowability. Mind 94: 557-68. Fitch, F. 1963. A logical analysis of some value concepts. Journal of Philosophical Logic 28: 135-42.

This article develops a comprehensive study of various types of interpolation properties and Beth definability properties (BDPs) for substructural logics, and their algebraic characterizations through amalgamation properties (APs) and epimorphisms surjectivity. In general, substructural logics are algebraizable but lack many of the basic logical properties that modal and superintuitionistic logics enjoy [Gabbay and Maksimova (2005, Oxford Logic Guides, Vol. 46)]. In this case, careful examination is necessary to see how these logical and algebraic properties are related. To describe these relations exactly, many variants of interpolation properties and BDPs, and also corresponding algebraic properties, are introduced. Because of their generality, the results reported here hold not only for substructural logics, but can also be extended to a more general setting such as abstract algebraic logic [Andreka, Nemeti and Sain (Handbook of Philosophical Logic, Vol. 2, 2nd edn, pp. 133–247) and Czelakowski and Pigozzi (1999, Vol. 203 of Lecture Notes in Pure and Applied Mathematics, pp. 187–265)].

This previously unpublished Syriac text consists of two parts, a dialogue between a Jew and a Christian concerning the abrogation of the Israelite priesthood by that of Jesus Christ in heaven and a list of key points where the former and the latter priesthoods differ. Although his main source is the pseudo-Pauline Epistle to the Hebrews, the author of this text was influenced by Greek philosophical logic and may have written this text with the aim of debating with Jews.

A ‘self-effacing’ property is one that is definable without referring to it. Colin McGinn has argued that there is exactly one such property: truth. I show that if truth is a self-effacing property, then there are very many others — too many even to constitute a set.

It has been common in contemporary philosophical logic to separate existence, essence and logic. I would like to reverse these separative tendencies. Doing so yields two theses, one about the existential basis of truth, the other about the essentialist basis of logic. The first thesis counters the common claim that both logical and essential truths—in short, structural truths—are existence-free. It is proposed that only real existences can generate essentialist and logical predications. The second thesis counters the common assumption that logic is free of essentialist involvement. I propose the contrary—logical predications are to be explained as a special kind of essentialist attributions.

The paper introduces ten open problems in belief revision theory, related to the representation of the belief state, to different notions of degrees of belief, and to the nature of change operations. It is argued that these problems are all issues in philosophical logic, in the strong sense of requiring inputs from both logic and philosophy for their solution.

Dummett, M. A. E. 1981. Frege and Wittgenstein. In Perspectives on the Philosophy of Wittgenstein, ed. I. Block, 31–42. Oxford: Basil Blackwell. Frege, G. 1980. Philosophical and Mathematical Correspondence. Oxford: Basil Blackwell. Geach, P. T. 1972. Quine on classes and properties. In his Logic Matters, 222–26. Oxford: Basil Blackwell. Geach, P. T. 1973. Frege. In G. E. M. Anscombe and P. T. Geach, Three Philosophers. Oxford: Basil Blackwell. Long, P. 1969. Are predicates and relational expressions incomplete? Philosophical Review 78: 90–98. Potter, M. 2000. Reason’s Nearest Kin. Oxford: Oxford University Press. Ramsey, F. P. 1931. The Foundations of Mathematics and Other Logical Essays. London: Kegan Paul. Russell, B. 1937. The Principles of Mathematics. London: George Allen & Unwin. Sullivan, P. M. 1991. The functional model of sentential complexity. Journal of Philosophical Logic 21: 91–108. Sullivan, P. M. 2000. The totality of facts. Proceedings of the Aristotelian Society 100: 175–92. Wittgenstein, L. 1922. Tractatus Logico-Philosophicus. London: Kegan Paul. Referred to as ‘TLP’. Wittgenstein, L. 1979. Notebooks 1914–1916. Oxford: Basil Blackwell. Referred to as ‘NB’.

For a large class of cases-though not for all-in which we employ the word “meaning” it can be defined thus: the meaning of a word is its use in the language . Wittgenstein (1953, §43) The purpose of this paper is to defend Wittgenstein's idea – his so-called “usetheory” of meaning – against what is perhaps the most influential of the many arguments that have been levelled against it. I'm thinking of Kripke's critique of “dispositionalism”, which is a central component of his celebrated essay, Wittgenstein on Rules and Private Language. Kripke argues that meaning a certain thing by a word is not a matter of being disposed to use it in a certain way. And his argument has been well-received. Most commentators, whatever they say about Kripke's overall line of thought (leading up to his “sceptical conclusion” about meaning), tend to agree at least that the use-theory has been elegantly demolished. My main objective is to combat this impression. Just what Wittgenstein himself had in mind is not entirely clear; but that's not my topic. Rather, what I want to do here is to explore and support a certain version of the use-conception of meaning – one which seems to me to have some attractive features (and which I believe can be pinned on Wittgenstein).

There is a long-standing distinction between characterizing an object and classifying it. To characterize an object is to compare it with others and find it similar in some way. It is to say, for example, that it is square, asymmetric, endothermic, crystalline at 500?K. To classify an object is to place it in a scheme of classes which embodies more than just a single fleeting comparison, but pur ports to encode the most important or salient features about it. It is to say, for example, that it is a golden eagle, a 1959 Cadillac De Ville, an automobile, some hydrogen sulfate, a gamma ray photon. This distinction has been recognized since antiquity. Aristotle distinguished predications in the category of substance, which tell us what something is?clas sifying it?from predications telling us how something is?characterizing it. (So, for example, predications in the categories of quantity, quality, place, rela tion etc., tell us what magnitude something is, what it is like, where it is, how it compares to another, etc.) The traditional distinction between characterizing and classifying an object has been rejected in modern philosophical logic, a fact reflected in the syntax and semantics of standard predicate logic. The predicates is a man and is white are dealt with equally as one-place predicates taking one nominal argument to form a sentence, and they are equally assigned a set of objects?those satisfying or falling under the predicate?as extension on a given interpretation. As Quine says, "Predication is illustrated indifferently by 'Mama is a woman', 'Mama is big', and 'Mama sings'. . . . The copula 'is' or 'is an' can accordingly be explained simply as a prefix serving to convert a general term from adjectival or

The doctrine of middle knowledge was developed by the Spanish Jesuits Luis de Molina and Francisco Suarez in the late sixteenth century, and immediately became the subject of fierce controversy, being bitterly opposed by the Dominicans, especially Domingo Bafiez and Diego Alvarez, and requiring the intervention of the Vatican (in 1607) to cause the bitterness to subside. As recent work has shown, the intellectual interest of the doctrine extends far beyond that of an inhouse debate in the Catholic Church of the Counter-Reformation; for it touches on issues of central importance not only in analytic theology, but also in philosophical logic. According to Molina, there are three moments in God's foreknowledge of the history of the world which He creates.' These moments are not to be thought of as stages in a temporal series, but as ordered by the relation of logical or conceptual dependence of later on earlier.2 In the first moment, God knows by natural knowledge all metaphysically necessary propositions. These include not merely truths of logic and mathematics, and natural laws, but also facts about which contingent states of affairs are possible, since that a state of affairs is possible is itself a necessary truth. God's natural knowledge would suffice to equip Him with complete foreknowledge of the history of His creation, if the world He created were entirely deterministic, and if He undertook to refrain from free intervention in that world. The creation

There is a view that is popular in the literature on philosophical logic according to which some sentences ('statives') are about states, whereas others ('nonstatives') are about events. I will take it for granted that there is some truth to this view, and address the issue of what a theory of semantics might look like that encapsulates it. How might a theory of language construe some sentences as being about events and others as being about states, and what might be the evidence in favour of or against such a theory? I think that there is such a theory, and that there is evidence in its favour; that is the topic of this paper. I begin with an old proposal, due to Frank Ramsey, according to which some rather ordinary sentences of English have logical forms which assert the existence of events. In his essay 'Facts and Propositions', Ramsey says: The connection between the event that was the death of Caesar and the fact that Caesar died is, in my opinion, this: 'That Caesar died' is really an existential proposition, asserting the existence of an event of a certain sort, thus resembling 'Italy has a king', which asserts the existence of a man of a certain sort. (Ramsey [1960] p. 141.) More recently Donald Davidson, extending a view of Hans Reichenbach's, defends a similar thesis about certain sentences of English. (Davidson [1967]) Davidson explicitly limits his account to a subset of English sentences; the key to this limitation is in the title of his essay, 'The Logical Form of Action Sentences'. This raises various questions: Is some version of the 'underlying event' account plausible for some sentences of English, as Ramsey suggests? If so, is it plausible for all of them, or only for 'action sentences', as Davidson (implicitly) suggests? More specifically, can such a theory be extended to stative sentences? My task in this paper is to answer these questions. In

Two quite different points have, on different occasions, been meant by, or been given as the meaning of, 'Existence is not a predicate'. The points may be related, but they are different points. This would not matter unless it resulted in confusion between the two points; unfortunately confusion has occurred on at least one occasion. My aim in this note is to show that such confusion can be found in D. F. Pears' 'Is Existence a Predicate?' (reprinted in Philosophical Logic, edited by P. F. Strawson). More precisely, my claim is that Pears is led to say some very strange things because he is trying to relate to one meaning of ENP ('Existence is not a predicate') remarks that were intended to relate to the other meaning. (i) The two points. The two points which have been linked with ENP are familiar. One we find in (amongst many other sources) Russell (e.g. Introduction to Mathematical Philosophy, Chapter I5). The point can at least be identified by the following statement: 'A's exist' is not about particular members (instances, arguments) or each member (instance, argument) of the class of A's (of the concept 'A', satisfying the function 'x is an A'); rather, it is about the class of A's (the concept 'A', the function 'x is an A'). Specifically to say that A's exist is to say that the class of A's has members (the concept 'A' has instances, the function 'x is an A' has arguments that satisfy it). Let us call this point the CMP (the classmembership point). The other point we can find stated in Pears' article (on p. 98). In the statement 'This room exists' the subject-phrase 'This room' implies that this room exists by making a reference to it, and thus the verb 'exists' is redundant. And in the statement 'This room does not exist' the verb contradicts what is implied by the subject-phrase. Pears describes the point in terms of 'referential tautologies' and 'referential contradictions' (let us call it the RTCP) and extends it (p. ioi) to cover general existential statements. Now, about the RTCP Pears says two particular things which I want to examine. He says that the RTCP is a refinement of two 'inexact formulations' of ENP; and he says that in his exposition of the RTCP, he is following up some ideas that G. E. Moore put forward in his article 'Is Existence a Predicate?' (Proceedings of the Aristotelian Society, Supp. Vol., I936. Reprinted in Logic and Language, Series II, edited by A. G. N. Flew.) (ii) The first inexact formulation (IFi). 'If I assert that tigers exist, the verb "exist" does not add anything to the concept of the subject "tigers" (P. 97). How does Pears show that the RTCP is 'really a refinement' of IFi? The connection is made through the idea of adding. In that the verb

Why and how is intensional logic important for philosophy? An adequate answer to this question would require a book. I will here consider some related problems which we must solve before we can begin to understand what is involved in any such answer. They are (i) What is intensional logic ? and (ii) What is the relation between intensional logic and the extensional logics with which most of us are so much more familiar. I will dwell on a particular aspect of the second problem in some detail. The only coherent formulations of the semantics for intensional logic which-to my knowledge at least-are available at the present time take the form of extensional theories which compensate for the lack of intensionality of their underlying logic by referring explicitly to possible worlds. This raises two further questions: (i) Can such a semantic theory ever be adequate? and (ii) Would this mean that intensional logic is reducible without remainder to extensional logic. There will be no room to discuss the last of these two. But I will have a number of things to say about the first.