This paper offers an explanation of the fact that sentences of the form (1) ‘X may A or B’ may be construed as implying (2) ‘X may A and X may B’, especially if they are used to grant permission. It is suggested that the effect arises because disjunctions are conjunctive lists of epistemic possibilities. Consequently, if the modal may is itself epistemic, (1) comes out as equivalent to (2), due to general laws of epistemic logic. On the other hand, (...) on a deontic reading of may, (2) is only implied under exceptional circumstances – which usually obtain when (1) is used performatively. (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.

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)

Grice observes that the primary discourse function of disjunction is the presentation of alternatives, each of which is relevant in the same way to a given topic. After a brief introduction , I offer in Chapter Two an account of Grice's observation and of further felicity conditions on disjunction, for example, the constraint against disjunctions in which one disjunct entails another. Using an enriched version of the Stalnakerian model of assertion, I define two constraints on information update--Relevant Informativity and Simplicity--and (...) show that these suffice to account for the observations. ;I then argue that the requirement to abide by Relevant Informativity and Simplicity provides a basis for an account of two further properties of disjunctive sentences: their presupposition projection properties and the possibility of anaphora between disjuncts. I argue that presuppositions project in disjunction except where projection would lead to infelicity of the kind characterized in Chapter Two. To state this account, a treatment of presupposition which allows projection to be sensitive to considerations of felicity is required. I show that the Stalnakerian view of presupposition, combined with Heim's notion of local accommodation, provides the necessary framework. ;Similarly, I argue that anaphora across disjunction is disallowed only when it leads to an infelicitous disjunction. In certain configurations, anaphora between disjuncts leads to entailment between disjuncts, which is ruled out independently. The account is given using a version of Neale's E-type analysis of unbound anaphora. I show that the analysis has further desirable consequences with respect to more complex examples of inter-disjunct anaphora. ;Throughout Chapters Three and Four, I contrast my own proposals with accounts given in the Dynamic Semantic literature, offering a critique of Dynamic Semantic approaches to the phenomena discussed. ;In Chapter Five, I examine anaphora between NPs contained inside a disjunction and a pronoun in a following sentence. I argue that these pronouns are also E-type, but show that these cases require a reformulation of the E-type analysis. I develop a new account in which the interpretation of E-type pronouns is derived compositionally from the content of the antecedent clause. (shrink)