ABSTRACT
Russell’s Multiple Relation Theory of Judgement was an elegant response to real problem, but Wittgenstein faults Russell’s idea for being unable to explain why certain constellations of entities are not judgeable. Wittgenstein proposed instead his celebrated ‘picture theory’ of the proposition. The crucial difference between propositions and pictures is just that the former accomplishes abstractly via conventions what the latter actually embodies. This leads Wittgenstein to say that anything that cannot be pictured in this way is not literally sayable; it can only be shown. Ayer puts the principle of verification at the centre of his philosophy. Meaningful propositions or statements are either analytic or (weakly) verifiable. Ayer applies the idea to several examples, including his account of physical objects, other minds, discourse about value, the past and future, and idealism versus realism. Carnap was the source of many of Ayer’s ideas but added some layers of sophistication as well as actually providing much of the formal work in logic that Ayer only describes informally. To close, the chapter considers the famous ‘Protocol Debate’ among members of the Vienna Circle (Carnap, Neurath, and Schlick).
