WITTGENSTEIN. By A.J. Ayer. Random House. 155 pp. $17.95.

A.J. AYER earned an early notoriety through a polemical and abrasive essay in analytical philosophy, his Language, Truth, and Logic of 1936. Though he later patronized this as very much a young man's book, Ayer remains, half a century later, largely committed to its once incendiary theses: that metaphysics is nonsense; that propositions are meaningful only if verifiable through sense experience; that though nonsense by this severe criterion, moral propositions have a kind of "emotive meaning" in that they express the feelings of those who utter them; and that philosophy has no task beyond elucidating the language and concepts of the natural sciences. His many writings have brought him considerable worldly respect in the form of important professorships at London and Oxford, as well as a knighthood. And they are throughout marked, as is this book, by an unfailing acuity and lucidity, an engaging urbanity and a wry wit, but also, it is perhaps not too harsh to add, by an unmistakable philistinism. Sir Alfred is numb to any writing he finds exotic, mystical, religious, or -- well -- metaphysical. This means, in the present book especially, that a certain class of utterances distinctive of its subject is ruled out by him as oracular noise.

The subject of the book, Ludwig Wittgenstein, is by common recognition one of the great philosophical thinkers of this century and perhaps of any century. Ayer, however restrained his enthusiasm for Wittgenstein -- "My admiration for him falls short of idolatry" -- places him nevertheless "second only to Bertrand Russell among the philosophers of the twentieth century." One would be hard pressed to identify more than two or three others as belonging in this restricted set -- Heidegger certainly, Sartre probably, Dewey possibly -- for philosophical genius remains rare even in a period in which philosophical competence can seldom have been higher or attained by so many. The literature on Wittgenstein, whether direct as commentary, or indirect as must be virtually everything written in English by philosophers since his work became known, is simply immense. And Ayer is as considerable a philosopher as any who have applied themselves to describing what Wittgenstein achieved as a thinker. Yet he is less qualified than many, in part through temperament, but also in part because he holds strong views on a good many of the issues to which Wittgenstein addressed himself, and which he feels constrained to defend against him.

Language, Truth, and Logic derived from certain views taken up from Wittgenstein by the Logical Positivist school of philosophy, to which Ayer belonged. And a central tenet of Ayer's theory of knowledge, the existence of private languages, was singled out for attack in a celebrated section of Wittgenstein's Philosophical Investigations. This book has, in consequence of the author's relationship with his subject, an air of setting the record straight, of taking Wittgenstein's thoughts up one by one, testing them against Ayer's own philosophical views, to see, on balance, how many survive and how many are simply wrong. In a way, it reads like a tutor's extended remarks on the papers of an immensely gifted but lamentably erratic pupil. The soul of Wittgenstein is screened out by this format.

Wittgenstein's writings fall into two main periods, with the central texts of each devoted to aspects of the philosophy of language. The Tractatus Logico-Philosophicus of 1922 sought to show how language must be if it is to represent the world and how the world must be if language is to represent it, as well as the limits of the sayable. The Philosophical Investigations, published posthumously in 1953, rejects the picture of language as representational completely, contending that languages go with certain forms of life, and that meaning is a matter of use, of what those who belong to a form of life do with the sentences they understand. But each of the books also expresses certain powerful, one might say mystical intuitions, about the deepest concerns of the self. The two main works are written in radically different styles: the Tractatus sets down seven theses, together with remarks and observations of varying degrees of importance, and each is given a kind of numerical value. The Investigations is composed of a sequence of brief dialogues between the narrator and an intimately addressed objector. There is scarcely a line in either book which is not dense with philosophical excitement, poetry, urgency and passion. And the thoughts expressed are at times so unusual, so powerful and unexpected as to leave the reader stunned. To be sure, the writing is often obscure, and often wrong when it is clear, but no study of Wittgenstein for a general audience can be adequate that does not convey an intense philosophical personality thinking at the limits of thought about those limits. Totting up scores and misses is not the way to do this.

Readers will enjoy the deft and amusing biographical sketch with which Ayer's book opens. They will profit from the concluding essay on Wittgenstein's influence, which is charmingly parochial, like a piece of family history, since Ayer writes from personal experience about those, himself included, who actually knew this fierce and original man. One can never seriously disrecommend a book by A.J. Ayer, but this one will be of primary interest to those who are interested in him, and are anxious to know what his views on specific theses of Wittgenstein are. But this means that readers not conversant with the recent history of theories of meaning, truth and knowledge, will find the discussion distant and abstract. If one wants to know about Wittgenstein, then better simply to read him. One will get quickly lost, but in compensation one will be moved and exalted. Perhaps the time to take this book up is when one is lost: but one pays a price for putting oneself in Professor Ayer's hands, and the sense of having found one's way may be an illusion. He himself is not always right, but soritng out the right from wrong belongs to the further literature of the subject.