Ayer on Monism, Pluralism and Essence

Abstract

After an initial section about a j ayer's "language, truth, and logic, and ayer's conceptions of monism, pluralism and essentialism, the article largely coincides (except with respect to its plentiful misprints and with respect to unfortunate house-editorial interventions) with chapter four of "sameness & substance" (blackwell 1980). necessity is treated not as a sentence operator, but as a predicate operator, the traditional conception. a version of miss barcan's necessity of identity result is proved. it is then suggested that the essential properties of a thing are those whose denial would subvert the singling out of that thing under a sortal concept adequate to determine the identity conditions of the thing. the high price of denying this modest doctrine is then assessed.