The possible-worlds semantics for modality says that a sentence is possibly true if it is true in some possible world. Given classical prepositional logic, one can easily prove that every consistent set of propositions can be embedded in a ‘maximal consistent set’, which in a sense represents a possible world. However the construction depends on the fact that standard modal logics are finitary, and it seems false that an infinite collection of sets of sentences each finite subset of which is (...) intuitively ‘possible’ in natural language has the property that the whole set is possible. The argument of the paper is that the principles needed to shew that natural language possibility sentences involve quantification over worlds are analogous to those used in infinitary modal logic. (shrink)
What makes the words we speak mean what they do? Possible-worlds semantics articulates the view that the meanings of words contribute to determining, for each sentence, which possible worlds would make the sentence true, and which would make it false. M. J. Cresswell argues that the non-semantic facts on which such semantic facts supervene are facts about the causal interactions between the linguistic behaviour of speakers and the facts in the world that (...) they are speaking about, and that the kind of causation involved is best analysed using David Lewis's account of causation in terms of counterfactuals. Although philosophers have worked on the question of the connection between meaning and linguistic behaviour, it has mostly been without regard to the work done in possible-world semantics and Language in the World is the first book-length examination of this problem. (shrink)
Is what could have happened but never did as real as what did happen? What did happen, but isn't happening now, happened at another time. Analogously, one can say that what could have happened happens in another possible world. Whatever their views about the reality of such things as possible worlds, philosophers need to take this analogy seriously. Adriane Rini and Max Cresswell exhibit, in an easy step-by-step manner, the logical structure of temporal and modal discourse, and show that (...) every temporal construction has an exact parallel that requires a language that can refer to worlds, and vice versa. They make precise, in a way which can be articulated and tested, the claim that the parallel is at work behind even ordinary talk about time and modality. The book gives metaphysicians a sturdy framework for the investigation of time and modality - one that does not presuppose any particular metaphysical view. (shrink)
The aim of this paper is to consider some logical aspects of the debate between the view that the present is the only 'real' time, and the view that the present is not in any way metaphysically privileged. In particular I shall set out a language of first-order predicate tense logic with a now predicate, and a first order (extensional) language with an abstraction operator, in such a way that each language can be shewn to be exactly translatable into the (...) other. I shew that this translation is preserved at the metalinguistic level, so that equivalent truth conditions can be defined in a tensed metalanguage or an indexical metalanguage. I then make some remarks about the connection between proofs of relative consistency and metaphysical truth; and some historical remarks about Arthur Prior's use of formal logic in expressing his presentist views. (shrink)
The paper introduces a first-order theory in the language of predicate tense logic which contains a single simple axiom. It is shewn that this theory enables times to be referred to and sentences involving ‘now’ and ‘then’ to be formalised. The paper then compares this way of increasing the expressive capacity of predicate tense logic with other mechanisms, and indicates how to generalise the results to other modal and tense systems.
David Lewis's modal realism claims that nothing can exist in more than one world or time, and that statements about how something would have been are to be analysed in terms of its counterpart . I first explain why the counterpart relation depends on de re modal statements in an intensional language, so that intuitive properties of similarity relations cannot be used to show that the counterpart relation is not an equivalence relation. I then look at test sentences in (the (...) intensional) natural language, and show that none of them provide compelling evidence that a counterpart semantics is needed. (shrink)
This paper explores a modal analogue of Hugh Mellor''s version of McTaggart''s argument against the reality of tense. I show that if Mellor''s argument succeeds in showing that the present moment cannot be any more real than any other moment then it also shows that the actual world cannot be any more real than any other possible world.
Book Information Logical Form and Language. Edited by G. Preyer and G. Peter. Clarendon Press. Oxford. 2002. Pp. x + 512. Hardback, £55. Paperback, £19.99.
I distinguish between sentences like(1) Last Thursday we drove from Wellington to Waikanae and (2) Last Thursday my copy of Aspects of the Theory of Syntax remained on my bookshelf. Sentence (2) has the subinterval property. If it is true at an interval t it is true at every subinterval of t. (1) lacks this property. (1) reports an event. (2) reports a state. Events do not have the subinterval property but states do have it, and so do objects. If (...) something is a linguist at an interval t then that person is a linguist at all subintervals of t. I argue that exists applies to things which have the subdinterval property, and occurs applies to things which lack it. (shrink)
This article discusses the argument we cannot have knowledge of abstract entities because they are not part of the causal order. The claim of this article is that the argument fails because of equivocation. Assume that the “causal order” is concerned with contingent facts involving time and space. Even if the existence of abstract entities is not contingent and does not involve time or space it does not follow that no truths about abstract entities are contingent or involve time or (...) space. I argue that it is the latter which is required to obtain the desired conclusion. (shrink)
A (normal) system of prepositional modal logic is said to be complete iff it is characterized by a class of (Kripke) frames. When we move to modal predicate logic the question of completeness can again be raised. It is not hard to prove that if a predicate modal logic is complete then it is characterized by the class of all frames for the propositional logic on which it is based. Nor is it hard to prove that if a propositional modal (...) logic is incomplete then so is the predicate logic based on it. But the interesting question is whether a complete propositional modal logic can have an incomplete extension. In 1967 Kripke announced the incompleteness of a predicate extension of S4. The purpose of the present article is to present several such systems. In the first group it is the systemswith the Barcan Formula which are incomplete, while those without are complete. In the second group it is thosewithout the Barcan formula which are incomplete, while those with the Barcan Formula are complete. But all these are based on propositional systems which are characterized by frames satisfying in each case a single first-order sentence. (shrink)
The paper considers the question of when the operator L of necessity in modal logic can be expressed in terms of the operator meaning it is non-contingent that.
Book Information The Voices of Wittgenstein: The Vienna Circle. The Voices of Wittgenstein: The Vienna Circle Ludwig Wittgenstein and Friedrich Waismann , ed. Gordon Baker , London : Routledge , 2003 , 528 , US$100 ( cloth ) Edited by Gordon Baker . By Ludwig Wittgenstein. and Friedrich Waismann. Routledge. London. Pp. 528. US$100 (cloth:).
In a number of publications A.N. Prior considered the use of what he called ‘metric tense logic’. This is a tense logic in which the past and future operators P and F have an index representing a temporal distance, so that Pnα means that α was true n -much ago, and Fn α means that α will be true n -much hence. The paper investigates the use of metric predicate tense logic in formalising phenomena ormally treated by such devices as (...) multiple indexing or quantification over times. (shrink)
Urn models were developed by Veikko Rantala to provide a non-standard semantics for first-order logic in which the domains, over which the quantifiers range, are allowed to vary. Rantala uses game-theoretical semantics in his presentation, and the present paper is a study of urn models from a more classical, truth-conditional point of view. An axiomatic system for urn logic is set out and completeness is proved by the method of maximal consistent sets.
A theory purporting to solve the problem of universals must be able to explain predication, recurrence, and classification. How Platonism does this is well known. Here I take a hard look at an attempt by M.J. Cresswell to give an Aristotelian answer and show it to be a complete and utter failure. The answer does not eliminate commitment to universals and it is only half an answer anyway because it does not cover relational predicates, an omission that Russell noted (...) dooms answers by other philosophers as well. (shrink)
This paper shows in detail how the formal semiotic of M. J. Cresswell [6] may be extended to provide an account of indirect question clauses in English. The resulting account is compared at various points with the theory recently propounded by Karttunen [12] and is argued to have two major advantages over the latter in that (i) it accommodates the manifest teleological relativity of who-clauses, and (ii) it avoids the need for categorial segregation of sentence-taking verbs from wh-clause-taking verbs (...) while offering a uniform explanation of various apparent semantic differences between them. (shrink)
I am idebted to members of the Wellington Logic Seminar for useful discussions of work of which this essay forms part, in particular to M. J. Cresswell for comments in the earlier stages of the investigation and to R. I. Goldblatt who suggested the definition ofB infD supu and made numerous other suggestions.
Die Reihe formaler Sprachen, die im Verständnis von M.J. Cresswell "sinnvoll" als Modelle für natüriiche Sprachen anzusehen sind und die dabei auch semantische Vagheiten zu erfassen gestatten, nämlich die dreiwertige Logik (U. Blau), die Superbewertung (B.C. van Fraassen, K. Fine, M. Pinkal, J. Ballweg) und die unscharfe Logik (L.A. Zadeh), legt nahe, daß bei der Sprachanalyse Zadehs "Prinzip der Inkompatibilität" gilt: Hohe Präzision ist inkompatibel mit hoher Komplexität. Je komplexer man das Vagheitsproblem angeht, desto verschwommener wird der benutzbare Geltungswert. (...) Zudem wird die Sprachanalyse auf Empirie verwiesen: Die Superbewertung erfordert eine Beschreibung von Kontexten, die unscharfe Logik eine sprachempirische Untersuchung aller Geltungswerte. (shrink)
These lecture notes were composed while teaching a class at Stanford and studying the work of Brian Chellas (Modal Logic: An Introduction, Cambridge: Cambridge University Press, 1980), Robert Goldblatt (Logics of Time and Computation, Stanford: CSLI, 1987), George Hughes and Max Cresswell (An Introduction to Modal Logic, London: Methuen, 1968; A Companion to Modal Logic, London: Methuen, 1984), and E. J. Lemmon (An Introduction to Modal Logic, Oxford: Blackwell, 1977). The Chellas text influenced me the most, though the order (...) of presentation is inspired more by Goldblatt.2 My goal was to write a text for dedicated undergraduates with no previous experience in modal logic. The text had to meet the following desiderata: (1) the level of difficulty should depend on how much the student tries to prove on his or her own—it should be an easy text for those who look up all the proofs in the appendix, yet more difficult for those who try to prove everything themselves; (2) philosophers (i.e., colleagues) with a basic training in logic should be able to work through the text on their own; (3) graduate students should find it useful in preparing for a graduate course in modal logic; (4) the text should prepare people for reading advanced texts in modal logic, such as Goldblatt, Chellas, Hughes and Cresswell, and van Benthem, and in particular, it should help the student to see what motivated the choices in these texts; (5) it should link the two conceptions of logic, namely, the conception of a logic as an axiom system (in which the set of theorems is constructed from the bottom up through proof sequences) and the conception of a logic as a set containing initial ‘axioms’ and closed under ‘rules of inference’ (in which the set of theorems is constructed from the top down, by carving out the logic from the set of all formulas as the smallest set closed under the rules); finally, (6) the pace for the presentation of the completeness theorems should be moderate—the text should be intermediate between Goldblatt and Chellas in this regard (in Goldblatt, the completeness proofs come too quickly for the undergraduate, whereas in Chellas, too many unrelated.... (shrink)
This paper specifies classes of framesmaximally omnitemporally characteristic for Thomas' normal modal logicT 2 + and for each logic in the ascending chain of Segerberg logics investigated by Segerberg and Hughes and Cresswell. It is shown that distinct a,scending chains of generalized Segerberg logics can be constructed from eachT n + logic (n 2). The set containing allT n + and Segerberg logics can be totally- (linearly-) ordered but not well-ordered by the inclusion relation. The order type of this (...) ordered set is *( + 1). Throughout the paper my approach is fundamentally semantical. (shrink)
