Quasi-Realism, Negation, and the Frege-Geach Problem

Every expressivist theory of moral language requires a solution to the Frege-Geach problem, i.e., the problem of explaining how moral sentences retain their meaning in unasserted (e.g., conditional and disjunctive) contexts. An essential part of Blackburn’s ‘quasi-realist project’, i.e., the project of showing how we can earn the right to treat moral sentences as if they have ordinary truth-conditions, is to provide a sophisticated solution. I show, however, that simple negated contexts provide a fundamental difficulty, since accepting the negation of a sentence is easily confused with merely refusing to accept that sentence. I argue that Blackburn’s model-set semantics for his ‘Hooray!’ and ‘Boo!’ operators requires logical apparatus to which he is not entitled. I consider various modifications, but show that they do not succeed