Article abstract: Ayer introduced the Austrian philosophy of logical positivism to the English-speaking world and continued the British empiricist and skeptical tradition of John Locke, George Berkeley, and David Hume. His contributions were primarily to the field of epistemology.
Alfred Jules Ayer’s father came from the French area of Switzerland and his mother from Belgium, although she was raised in England. The couple was residing in London when their only child was born in 1910. Ayer spent much of his early life in solitude, enjoying stamp collecting and reading. By age seven, he was in a boarding school, and when he was almost thirteen, he received a scholarship to Eton. There he first read philosophy, including works by contemporary thinkers Bertrand Russell and G. E. Moore, and though confirmed in the Church of England, he became a lifelong “militant” atheist. At the suggestion of his maternal grandfather, whom Ayer identified as the greatest influence on his life, in 1929 he entered Oxford University with the intention of becoming a barrister.
In Christ Church College at Oxford, he studied ancient history and philosophy. His principal tutor was Gilbert Ryle, who would later gain recognition and wide influence as the author of The Concept of Mind (1949). Isaiah Berlin, philosopher of political theory and intellectual history, became a lasting friend of Ayer when the two met through the Jowett Society, the undergraduate philosophical group of which Ayer was secretary. After completing three years of study, Ayer, at Ryle’s recommendation and despite a desire to work with Ludwig Wittgenstein at Cambridge, spent an academic year (1932-1933) in Vienna, where he participated in the weekly meetings of a group of Austrian philosophers, physicists, and mathematicians who developed the perspective of logical positivism and called themselves the Vienna Circle. They sought to rid philosophy of its metaphysical speculation and to unite the natural sciences. Their leader was Moritz Schlick, professor of philosophy at the University of Vienna, whose lectures Ayer attended. The observations made in the circle provided the basis for Ayer’s Language, Truth, and Logic, which would introduce Ayer to the world of professional philosophy.
Language, Truth, and Logic was the first systematic introduction of logical positivism for the English reader and became Ayer’s best-known and most widely read work. Ayer held that logical positivism was a natural extension of the British empirical tradition of John Locke, George Berkeley, and David Hume and logically followed from the work of Bertrand Russell and Ludwig Wittgenstein, particularly the latter’s “Logisch-philosophische Abhandlung” (1921; best known by the bilingual German and English edition title of Tractatus Logico-Philosophicus, 1922, 1961).
Logical positivism rested on the premise that all propositions could be sorted into two classes: The first contained propositions that were either true by form (tautologies from mathematics and logic or definitional claims such as “All unmarried men are bachelors”) or verifiable (testable) by some empirical means. The second category contained all remaining propositions. These were deemed to be neither true nor false but rather nonsensical. That is, the latter class of propositions were not merely untrue claims about the world—they really were not claims at all, for they could not meet the most fundamental test of any proposition, which is that a proposition must make a meaningful claim. The meaningfulness of a claim was to be assessed by the principle of verification. It was this principle that allowed for the sorting of propositions into their appropriate and respective category or class.
The principle of verification asserted that a claim was “factually significant” if one knew what observation or evidence could lead to demonstrating its truth or falsity. One was not required to be able to actually carry out...
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