Counterfactuals is David Lewis' forceful presentation of and sustained argument for a particular view about propositions which express contrary to fact conditionals, including his famous defense of realism about possible worlds and his theory of laws of nature.

Because statements like ‘This object is soluble in aqua regia’ involve the causal modalities, we call them causal dispositional statements. Now while this involvement has long been recognized, no thorough examination of its exact nature has ever been made. One purpose of this paper is to begin such an examination. In Sec. 2 we will suggest an analysis of causal dispositional statements, and in Sec. 3 we will discuss some philosophic issues to which this analysis is relevant.

In this paper a formalized logic of propositions, PA1, is presented. It is proven consistent and its relationships to traditional logic, to PM ([15]), to subjunctive (including contrary-to-fact) implication and to the “paradoxes” of material and strict implication are developed. Apart from any intrinsic merit it possesses, its chief significance lies in demonstrating the feasibility of a general logic containing theprinciple of subjunctive contrariety, i.e., the principle that ‘Ifpwere true thenqwould be true’ and ‘Ifpwere true thenqwould be false’ are incompatible.

Relative to any point in time, how many possible futures are there? For example, it may rain tomorrow, or again it may not. So it would appear that relative to today, there are at least two possible futures, one involving rain tomorrow and the other not. Of course only one of these two future states of affairs will take place, and in that sense there is only one actual future, though there may be many possible futures. The only hypothesis under (...) which there is, for every instant in time, only one possible future, is the hypothesis of universal Laplacean determinism, and this hypothesis has had little to recommend it since the advent of quantum physics. Furthermore, although among the many possible futures relative to any given moment in time there is only one which will become actual, no distinguishing mark separates this one from its fellows at the given moment. So it would appear that what confronts the world at each moment in time is an undifferentiated multiplicity of possible futures. But this multiplicity, though at first sight admittedly frightening in its implications, may be put to good philosophical use: as will be seen it yields natural and convincing definitions of the notions of physical necessity and possibility. On the other hand, alternative definitions of these notions are obtainable which do not make use of the manifold of possible futures, and these also will be presented. The paper will be in two parts, the first dealing with the concepts of physical possibility and necessity, and the second presenting a formal calculus of necessary and sufficient conditions in which the physical modalities find their place. (shrink)

The aim of the book is to introduce the reader to some new areas oflogic which have yet to find their way into the bulk of modern logic books written from the more orthodox direction of the mainstream of develop ments. Such a work seems to me much needed, both because of the in trinsic value and increasing prominence of the nonstandard sector of logic, and because this particular sector is of the greatest interest from the standpoint of philosophical implications (...) and applications. This book unites a series of studies in philosophical logic, drawing for the most part on material which I have contributed to the journal liter ature of the subject over the past ten years. Despite the fact that some of these essays have been published in various journals at different times, they possess a high degree of thematic and methodological unity. All of these studies deal with material of substantial current interest in philo sophical logic and embody a fusion of the modern techniques of logical and linguistic-philosophical analysis for the exploration of areas of logic that are of substantial philosophical relevance. (shrink)