First edition. 8vo. [2], 28, [2] pp. Original printed wrappers, stapled as issued. A very good copy. London, H.K. Lewis & Co. Ltd, 1947.
Ayer’s inaugural lecture as Grote Professor of the Philosophy of Mind and Logic at University College, London. Ayer would never reprint the article, mainly because he thought it owed too much to Gilbert Ryle, to whom it is dedicated.