Conditional sentences are among the most intriguing and puzzling features of language, and analysis of their meaning and function has important implications for, and uses in, many areas of philosophy. Jonathan Bennett, one of the world's leading experts, distils many years' work and teaching into this book, making it the fullest and most authoritative treatment of the subject.

A very simple contextualist treatment of a sentence containing an epistemic modal, e.g. a might be F, is that it is true iff for all the contextually salient community knows, a is F. It is widely agreed that the simple theory will not work in some cases, but the counterexamples produced so far seem amenable to a more complicated contextualist theory. We argue, however, that no contextualist theory can capture the evaluations speakers naturally make of sentences containing epistemic modals. If (...) we want to respect these evaluations, our best option is a relativist theory of epistemic modals. On a relativist theory, an utterance of a might be F can be true relative to one context of evaluation and false relative to another. We argue that such a theory does better than any rival approach at capturing all the behaviour of epistemic modals. (shrink)

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.

Consider a superagent, a being with extraordinary rational capactities. Not only are a superagent’s beliefs closed under entailment, but a superagent also has a wonderful kind of introspective awareness: whenever she believes that she doesn’t believe something, she is right—she doesn’t believe it. A superagent, then, is a being who satisfies the following two principles: (I) If p entails q, and if S believes p, then S believes q. (II) If S believes that she doesn’t believe p, then S doesn’t (...) believe p. I don’t suppose anyone thinks that there is such a thing as a superagent, or that there ever will be. But I do suppose that there could be a superagent, in the sense that it’s not conceptually impossible for a superagent to exist. Our concept of belief, whatever it is, should not be such as to rule out the possibility of a being of this kind. In this paper I expose a paradox: although our concept of belief shouldn’t rule out the possibility of a being of this kind, it apparently does.1 I end the paper by arguing that the key to solving this paradox lies in the recognition that the question of whether an agent could believe so-and-so can sometimes diverge from the question of whether it is possible that she believes so-and-so. (shrink)

Suppose the world is chancy. The worry arises that most ordinary counterfactuals are false. This paper examines David Lewis' strategy for rescuing such counterfactuals, and argues that it is highly problematic.

In this paper I offer an account of the meaning of must and can within the framework of possible worlds semantics. The paper consists of two parts: the first argues for a relative concept of modality underlying modal words like must and can in natural language. I give preliminary definitions of the meaning of these words which are formulated in terms of logical consequence and compatibility, respectively. The second part discusses one kind of insufficiency in the meaning definitions given in (...) the first part, which arise from the ex falso quodlibet paradox of logical consequence. In stepwise fashion, I make an attempt to avoid most of the consequences of this paradox for the meaning definitions of must and can. (shrink)