Language, Truth and Logic, a work of philosophy by Alfred Jules Ayer, published in 1936) defines, explains and argues for the verification principle of logical positivism, sometimes referred to as the "criterion of significance" or "criterion of meaning". The treatise explains how the principle of verifiability may be applied to the problems and aims of philosophy.

The text has eight chapters, entitled: “Ch. I. The Elimination of Metaphysics,” “Ch. II. The Function of Philosophy,” “Ch. III. The Nature of Philosophical Analysis,” “Ch. IV. The A Priori,” “Ch. V. Truth and Probability,” “Ch. VI. Critique of Ethics and Theology,” “Ch. VII. The Self and the Common World,” “Ch. VIII. Solutions of Outstanding Philosophical Disputes.”

Sir Alfred Jules Ayer (October 29, 1910 – June 27, 1989), better known as A. J. Ayer (or Freddie by his friends), was a British philosopher known for his promotion of logical positivism, particularly in his books Language, Truth and Logic (1936) and The Problem of Knowledge (1956).

Ayer was the Grote Professor of the Philosophy of Mind and Logic at the University College London from 1946 until 1959, when he became Wykeham Professor of Logic at Oxford University. He was knighted in 1970.