Paul Horwich

In the final chapter the possibility of time travel is defended. The starting point is Godel's discovery of solutions to Einstein's field equations. These permits the sort of closed causal chains involved in backwards time travel. My concern is to rebut those arguments to show the conceptual absurdity and physical impossibility of these solutions. ;The third chapter consists of an exposition and criticism of Grunbaum's views on the metrics of space and time. I argue that he fails to provide a non-trivial basis for conventionalism and I urge several objections against his claim that space and time are intrinsically metrically amorphous. I also discuss, and attempt to undermine Grunbaum's critique of the theory of Geometrodynamics. ;This dissertation deals with some philosophical problems concerning the measurement of time and its topology. ;The first two chapters are devoted to an examination of the thesis that correct attribution of congruence to pairs of temporal intervals depends upon convention rather than fact. My main conclusions are: that insofar as this thesis is true, it is no more than a subthesis of trivial semantical conventionalism--the view that any sentence depends for its truth-value, not only upon the nature of things, but also upon the conventional association of the sentence with its meaning. that, nevertheless, a substantive conventionalist claim may be made if one specifies the degree to which the extension of a temporal predicate is left underdetermined by certain elements of its meaning. This is illustrated for the case of simultaneity. that there are theories, observationally indistinguishable from standard physics, which yield non-standard congruence results. In these theories instants of time have unusual causal properties. Our grounds for rejecting them involve the existence of reference-fixing stipulations for the nature of congruence. I claim that we know such theories to be false in much the same way we know that the standard meter-bar is not two meters long

This paper questions the idea that Wittgenstein’s account of meaning as use requires an intrinsically normative understanding of this notion, and suggests instead that Wittgenstein is better understood as promoting a naturalistic view of meaning that undertakes an explanation based on non–semantic and non–normative facts of word–usage. It discusses the relevant positions of Kripke, Brandom and McDowell, all of whom are found to be united by the attempt to attribute to Wittgenstein a normative understanding of language that is not convincing. While language does exhibit normative properties that cannot be naturalized, the understanding speakers have of their own words is “a prima facie plausible candidate for naturalistic analysis.”

Discussion of Wittgenstein's philosophy has suffered from a scarcity of commentators who understand his work well enough to explain it in their own words. Apart from certain notable exceptions, all too many advocates and critics alike have tended merely to repeat slogans, with approval or ridicule as the case may be. The result has been an unusual degree of polarization and acrimony—some philosophers abandoning normal critical standards, falling under the spell and becoming fanatical supporters; and others taking an equally extreme opposite view, deriding the absence of analytic technique, and refusing to see anything of value in Wittgenstein's work.

This paper offers a critique of mainstream formal semantics. It begins with a statement of widely assumed adequacy conditions: namely, that a good theory must (1) explain relations of entailment, (ii) show how the meanings of complex expressions derive from the meanings of their parts, and (iii) characterize facts of meaning in truth-theoretic terms. It then proceeds to criticize the orthodox conception of semantics that is articulated in these three desiderata. This critique is followed by a sketch of an alternative conception—one that is argued to be more in tune with the empirical objectives of linguistics and the clarificatory aims of philosophy. Finally, the paper proposes and defends a specific theoretical approach—use based rather than truth based—that is suggested by that alternative conception.