Timothy Williamson gives an original and provocative treatment of deep metaphysical questions about existence, contingency, and change, using the latest resources of quantified modal logic. Contrary to the widespread assumption that logic and metaphysics are disjoint, he argues that modal logic provides a structural core for metaphysics.

Preface This book is about semantics and logic. More specifically, it is about the semantics and logic of natural language; and, even more specifically than ...

But Findlay's remark, like so much that has been written on the subject of time in the present century, was provoked in the first place by McTaggart's ...

The relationship between formal logic and general philosophy is discussed under headings such as A Re-examination of Our Tense-Logical Postulates, Modal Logic in the Style of Frege, and Intentional Logic and Indeterminism.

This book is collection of the the author’s previously published papers on the philosophy of modality and tense and it also includes three unpublished papers. The author provides an exposition and defence of certain positions for which he is well-known: the intelligibility of modality de re; the primitiveness of the modal; and the primacy of the actual over the possible. He also argues for some less familiar positions: the existence of distinctive forms of natural and normative necessity, not reducible to (...) any form of metaphysical necessity; the need to make a distinction between the worldly and unworldly, analogous to the distinction between the tensed and the tenseless; and the viability of a nonstandard form of realism about tense, which recognizes the tensed character of reality without conceding there is any privileged standpoint from which it is to be viewed. (shrink)

This is a revised and expanded edition of a seminal work in the logic and philosophy of time, originally published in 1968. Arthur N. Prior (1914-1969) was the founding father of temporal logic, and his book offers an excellent introduction to the fundamental questions in the field. Several important papers have been added to the original selection, as well as a comprehensive bibliography of Prior's work and an illuminating interview with his widow, Mary Prior. In addition, the Polish logic which (...) made Prior's writings difficult for many readers has been replaced by standard logical notation. This new edition will secure the classic status of the book. (shrink)

The theorems of the simplest and strongest sensible quantified modal logic include the Barcan Formula and its converse. Both formulas face strong intuitive objections. This paper develops a theory of possibilia to meet those objections.

Ulrich Meyer defends a novel theory about the nature of time, and argues against the consensus view that time and space are fundamentally alike. He presents the first comprehensive defense of a 'modal' account, which emphasizes the similarities between times and possible worlds in modal logic, and is easily reconciled with the theory of relativity.

' I heartily recommend it to any philosopher of language interested in the issues. [] Logicians, of course, will want to savour the whole thing.' Australian Journal of Philosophy, 71:3 (1993).

Our model of time is the classical continuum of real numbers, and our model of other measurable quantities that change over time is that of functions defined on real numbers with real numbers as values. This model is not derived from reality or from our experience of it, but imposed on reality; and the fit is very imperfect. In classical mathematics, the value of a function for any real number as argument is independent of its value for any other argument: (...) the analogue is Hume's doctrine that events are loose and separate. This makes continuity in the change of any quantity a contingent law of physica, rather than a conceptual necessity. The article explores alternatives to this classical model. (shrink)

I argue that David Lewis is too quick to deny the presentist the right to employ span operators. There is no reason why the presentist could not help herself to both primitive tensed slice operators and primitive span operators. She would then have another device available to eliminate ambiguities and explain why sentences with embedded contradictions may nevertheless be true.

Fara and Williamson (Mind, 2005) argue that counterpart theory is unable to account for modal claims that use an actuality operator. This paper argues otherwise. Rather than provide a different counterpart translation of the actuality operator itself, the solution presented here starts out with a quantified modal logic in which the actuality operator is redundant, and then translates the sentences of this logic into claims of counterpart theory.

Many philosophers believe there to be a fundamental difference between the present and past and future times, but they tend to disagree amongst themselves about what this difference is. Some think that the present is singled out by consciousness, while others believe that it marks the position to which the flow of time has advanced. According to presentism, the current moment is ontologically privileged: nothing exists that is not present. My aim in this chapter is to argue that this particular (...) attempt at distinguishing the present from other times is unsuccessful. (shrink)

It is shown how the modal actualist might make sense of quantification over possible worlds and the tense-logical presentist might make sense of quantification over instants.

A‐theorists of time postulate a deep distinction between the present, past and future. Settling on an appropriate logic for such a view is no easy matter. This Philosophy Compass article describes one of the most vexing formal problems facing A‐theorists. It is commonly thought that A‐theories can only be formally expressed in a tense logic: a logic with operators like P and F . And it seems natural to think that we live in a world where objects come to exist (...) and cease to exist as time passes. Indeed, this is typically a key component of the most prominent kind of A‐theory, presentism. But the temporary existence assumption cannot be upheld in any tense logic with a standard quantification theory. I will explain the problem and outline the philosophical and logical considerations that generate it. I will then consider two possible solutions to the problem – one that targets our logic of quantification and one that targets our assumptions about change. I survey the costs of each solution. (shrink)

Sufficient texts show that for aristotle the universal notion expresses the same real thing as the particular, Though in a different way. His grounds for a universal so conceived are twofold. First, In every sensible thing there is a basic formal principle that, Though individual, Brings each instance into formal identity with all the other instances. Secondly, In human intellectual cognition there is an active principle that raises knowledge above the status of photographing or registering or cataloguing, And actualizes what (...) was only potential in the real thing. In knowing sensible things universally, The human intellect is able to grasp the concrete thing as characterized by a formal nature, Thereby knowing it in a way that holds equally for all other instances. Though patently incomplete, This conception of the universal is free from internal contradictions. It provides a framework for fruitful discussion, And remains a challenge. (shrink)

This paper explains how to obtain quantification over times in a tense logic in which all temporal distinctions are ultimately spelled out in terms of the two simple tense operators “it was the case that” and “it will be the case that.” The account of times defended here is similar to what is known as “linguistic ersatzism” about possible worlds, but there are noteworthy differences between these two cases. For example, while linguistic ersatzism would support actualism, the view of times (...) defended here does not support presentism. (shrink)

According to Hans Kamp and Frank Vlach, the two-dimensional tense operators “now” and “then” are ineliminable in quantified tense logic. This is often adduced as an argument against tense logic, and in favor of an extensional account that makes use of explicit quantification over times. The aim of this paper is to defend tense logic against this attack. It shows that “now” and “then” are eliminable in quantified tense logic, provided we endow it with enough quantificational structure. The operators might (...) not be redundant in some other systems of tense logic, but this merely indicates a lack of quantificational resources and does not show any deep-seated inability of tense logic to express claims about time. The paper closes with a brief discussion of the modal analogue of this issue, which concerns the role of the actuality operator in quantified modal logic. (shrink)

We present a Hilbert style axiomatisation for the set of formulas in the temporal language with F and P which are valid over non-transitive cyclical flows of time. We also give a simpler axiomatisation using the slightly controversial 'irreflexivity rule' and go on to prove the decidability of any temporal logic over cyclical time provided it uses only connectives with first-order tables.

With the rigorous development of modal logic in the first half of the twentieth century, it became custom amongst philosophers to characterize different views about necessity and possibility in terms of rival axiomatic systems for the modal operators ‘ ’ (‘possibly’) and ‘ ’ (‘necessarily’). From the late 1950s onwards, Arthur Prior began to argue that temporal distinctions ought to be given a similar treatment, in terms of axiomatic systems for sentential tense operators, such as ‘P’ (‘it was the case (...) that’) and ‘F’ (‘it will be the case that’).1 My aim here is to give a brief survey of the extent to which time can be treated on the model of modality. I shall not try to address the further question of whether such ‘modal’ accounts of time are to be preferred over ‘spatial’ accounts that treat times more like places. (shrink)

Michael Dummett claims that the classical model of time as a continuum of instants has to be rejected. In his view, “it allows as possibilities what reason rules out, and leaves it to the contingent laws of physics to rule out what a good model of physical reality would not even be able to describe.” This paper argues otherwise.

Ulrich Meyer's objections to Dummett's arguments on the time continuum fail because he takes Dummett to endorse Hume's atomistic doctrine that events are ‘loose and separate’, In fact, Dummett rejects this doctrine. He used it in his original article only to indicate that certain implications which are conceptually possible fom the point of view of the classical model of time are not actually conceptually possible.

Review of Tense Logic, ed. by Lennart Åqvist and Frans Guenthner,.