Transworld Similarity and Transworld Belief

Abstract Relations of trans world similarity play an essential role in Lewis’s system. Analysis reveals that they involve the possibility of detailed trans world belief. Such belief is problematic within Lewis’s framework. He has an answer to the problems raised, but it relies on a dubious distinction between natural and mere properties. Replacing that distinction with a respectable one undermines an essential part of his case against one of his chief opponents, the linguistic ersatzist. David Lewis’s untimely demise leaves a legacy which is a jewel in the crown of 20th Century analytical philosophy-a systematic metaphysical system, with its core doctrines in the theory of possible worlds meticulously detailed, and their implications carefully traced, through semantics and the philosophy of mind, even unto the realms of value theory. It is, then, natural that the lengthy, more-or-less annual visits to Australia, made following his first visit in 1971 as a Gavin David Young Lecturer to the University of Adelaide, should have made a weighty impact on the Australian philosophical community. After all, part of the attraction of the place for him was that its philosophical climate was already predisposed to systematic metaphysics; moreover, even in this age of easy access and communication, Lewis’s contact with the Australian philosophical community as a whole far exceeded that of any comparable external influence over the past twenty years.