LONDON — Sir Alfred J. Ayer, a pioneering British philosopher who used the science of language to understand the principles of logic, has died at 78.
Ayer died Tuesday night after a lengthy respiratory illness in University College Hospital.
Ayer is known to generations as A. J. Ayer and to friends as Freddie. His first book, "Language, Truth and Logic," in 1936 was the first exposition of logical positivism in the English language. Ayer said that for any statement to mean anything it must be verifiable by experience or analysis, and, if that wasn't possible, then the statement is merely an expression of opinion.
This led him to atheism, for which he was often criticized.