Logical positivism

Logical Positivism was philosophical school originating in Vienna in the early years of the Twentieth century. The originators of the philosophy is often referred to as the "Vienna Circle". The Circle's views was first brought to the attention of the English speaking world by A. J. Ayer in his work "Language, Truth and Logic".

Logical Positivism sought to eliminate metaphysics from philosophy to which end it proposed a criterion of verifiability:

"a sentence was facually significant to any given person, if, and only if, he knows what observations would lead him , under certain conditions , to accept the proposition as being true, or accept it as being false." ( A. J. Ayer, "Language, Truth and Logic" Second Edition, Victor Gollancz Ltd, 1956 page 35).

That was to say that if there was no empirical evidence, for or against, the proposition the propostion fails to have any meaning: it was simply nonesense.