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Ayer, Alfred Jules (1910–89)

DOI: 10.4324/9780415249126-DD006-1
Version: v1,  Published online: 1998
Retrieved January 18, 2018, from

Article Summary

A.J. Ayer made his name as a philosopher with the publication of Language, Truth and Logic in 1936, a book which established him as the leading English representative of logical positivism, a doctrine put forward by a group of philosophers known as members of the Vienna Circle. The major thesis of logical positivism defended by Ayer was that all literally meaningful propositions were either analytic (true or false in virtue of the meaning of the proposition alone) or verifiable by experience. This, the verificationist theory of meaning, was used by Ayer to deny the literal significance of any metaphysical propositions, including those that affirmed or denied the existence of God. Statements about physical objects were said to be translatable into sentences about our sensory experiences (the doctrine known as phenomenalism). Ayer further claimed that the propositions of logic and mathematics were analytic truths and that there was no natural necessity, necessity being a purely logical notion. Finally the assertion of an ethical proposition, such as ‘Stealing is wrong’, was analysed as an expression of emotion or attitude to an action, in this case the expression of a negative attitude to the act of stealing.

During the rest of his philosophical career Ayer remained faithful to most of these theses, but came to reject his early phenomenalism in favour of a sophisticated realism about physical objects. This still gives priority to our experiences, now called percepts, but the existence of physical objects is postulated to explain the coherence and consistency of our percepts. Ayer continued to deny that there were any natural necessities, analysing causation as consisting in law-like regularities. He used this analysis to defend a compatibilist position about free action, claiming that a free action is to be contrasted with one done under constraint or compulsion. Causation involves mere regularity, and so neither constrains nor compels.

Citing this article:
MacDonald, Graham. Ayer, Alfred Jules (1910–89), 1998, doi:10.4324/9780415249126-DD006-1. Routledge Encyclopedia of Philosophy, Taylor and Francis,
Copyright © 1998-2018 Routledge.

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