Frege-Geach problem and metaethical expressivism

Abstract

This article consists of four parts: introduction which includes an explanation of what Frege-Geach (FG) problem is; Blackburn's solution of the problem; Gibbard's solution of the problem and author's conclusion. The origin of the FG problem is not ethics nor metaethics, but logic. The key question of the FG problem is: What is the (semantic or other) function of the so-called Frege's 'assertoric sign' in 'unasserted contexts'. In metaethical non-cognitivism the problem derived from this question is: what is the status of antecedent in 'moral modus ponens'. Two 'non-cognitivists', 'exspressivists' and 'quasirealists', Blackburn and Gibbard, have almost the same idea: without necessary philosophical intervention antecedent in moral modus ponens cannot has same status which it has in modus ponens of classical logic. They think we can expand notions of so-called 'operators' (logical and moral) and even construct artificial languages to make that kind of 'logic' possible. Author concludes that those ideas are counter-intuitive, logically problematic and even unintelligible. So FG problem cannot be solved from 'quasi-realistic' prospective.