The Similarity Approach to Truthlikeness

Abstract

The similarity approach to truthlikeness was discovered in 1974, in two different forms and independently of each other, by Risto Hilpinen within possible worlds semantics (see Hilpinen, 1976) and Pavel Tichý within propositional logic (see Tichý, 1974). The convergence of their apparently different ideas, and the application of the general approach to monadic first-order logic, was given in my paper for the 1975 International Congress for Logic, Methodology, and Philosophy of Science in London, Ontario (see Niiniluoto, 1977b). Later extensions cover full first-order logic (Tichý, 1976, 1978; Niiniluoto, 1978a, b; Tuomela, 1978; Oddie, 1979), higher-order and intensional logics (Oddie, 1982; Niiniluoto, 1983b), probabilistic hypotheses (Rosen-krantz, 1980), and quantitative languages (Niiniluoto, 1982b, c, 1986a, c; Festa, 1986). The technical and philosophical controversies surrounding this approach have ranged from disagreements about the details in working out the programme (cf. Oddie, 1981; Niiniluoto, 1982a) to more general challenges to the whole enterprise (cf. Miller, 1976, 1978; Popper, 1976;Urbach, 1983).¹