Abstract

The view that some version of comparative similarity ordering is capable of supporting an analysis of the counterfactual conditional is defended. ;Comparative order semantics, a generalization of Lewis' comparative similarity semantics, is developed. In comparative order semantics, possible worlds are ordered relative to each world as a basis for comparison. The smallest logic, CP, in which the order relative to each world is a partial order, is identified. A number of logics of the counterfactual conditional that have been suggested contain CP, though in some cases the results presented in this essay are surprising, and at variance with what has been claimed elsewhere. In particular, a family of logics is identified which lies between previously identified logics whose comparative order semantics are partially ordered , and certain of the V-logics of Lewis . The smallest member of this intervening family is characterized by a semiconnected partial order. ;In addition, a formal comparison of modal and conditional logics is undertaken, using neighborhood semantics, as well as a formal comparison of a variety of normal conditional logics, using selection function semantics. Various families of normal conditional logics are thereby identified. These families are classified in terms of two dimensions: one of increasing materiality of the conditional connective, and the other of increasing strength in the comparison of possible worlds implicit in any semantics for the logics. Much of this work is a continuation of that of Brian Chellas and Donald Nute. ;Recently, possible world semantics has provided a basis for several accounts of the counterfactual conditional that offer theories of counterfactual deliberation superior to that of previous, so-called metalinguistic, accounts. The present essay is a survey of a number of these possible world accounts, with particular emphasis on that of David K. Lewis. It is argued that possible world accounts more closely resemble scientific theories than they do traditional conceptual analyses. The view that what is at issue is a central concept of conditionality, rather than a more narrow notion of counterfactuality or subjunctivity, is espoused