Maggs Bros.

Ayer’s first and most famous book, complete with the rare dust jacket, vital for bringing the ideas of the Vienna Circle to the English-speaking world, ‘written at the age at which (as he liked to recall) David Hume had written his Treatise of Human Nature (1739). It was his version of Viennese logical positivism, though he also saw it as a recasting of the traditional theses of British empiricism into linguistic terms. The book is full of passionate iconoclasm, expressed in a fine cadenced prose. Its central thesis is the verification principle, which divided all statements into the verifiable or the unverifiable. Verifiable statements were either, like everyday beliefs or science, reducible to observation statements, or, like mathematics or logic, transformable by means of definitions into tautologies, and only they were meaningful. Unverifiable statements (metaphysics, ethics, religion) were literally nonsense’ (ODNB).