GRIPH Lecture: Bolzano's argument for the Identity of Indiscernibles

Bolzano's argument for the Identity of Indiscernibles

Abstract: The Principle of Identity of Indiscernibles rules out purely numerical difference: if it is true, then every two things must differ in some (extra-numerical) way. This principle has been widely debated since the time of Leibniz, who installed the principle at the centre of the metaphysical debate. There is a variety of arguments for it, though all of them are based on controversial premises. The case of Bolzano is interesting in this regard. For in hisWissenschaftslehre he produced an original, interesting, and intriguing argument for it which is, unlike any other argument for the principle, based on probabilistic reasons. In this talk I shall examine the relevant passage, compare it with Leibniz's arguments for it, attempt a reconstruction of the argument and evaluate it.