“Certain” represents an assessment of the evidence for a conclusion; it is usually contrasted with two other broad types of assessment: “possible” and “probable.” . . .

Idea X is “certain” if, in a given context of knowledge, the evidence for X is conclusive. In such a context, all the evidence supports X and there is no evidence to support any alternative . . . .

You cannot challenge a claim to certainty by means of an arbitrary declaration of a counter-possibility, . . . you cannot manufacture possibilities without evidence . . . .

All the main attacks on certainty depend on evading its contextual character . . . .

The alternative is not to feign omniscience, erecting every discovery into an out-of-context absolute, or to embrace skepticism and claim that knowledge is impossible. Both these policies accept omniscience as the standard: the dogmatists pretend to have it, the skeptics bemoan their lack of it. The rational policy is to discard the very notion of omniscience. Knowledge is contextual—it is knowledge, it is valid, contextually.

Infallibility is not a precondition of knowing what one does know, of firmness in one’s convictions, and of loyalty to one’s values.

“Don’t be so sure—nobody can be certain of anything.” Bertrand Russell’s gibberish to the contrary notwithstanding, that pronouncement includes itself; therefore, one cannot be sure that one cannot be sure of anything. The pronouncement means that no knowledge of any kind is possible to man, i.e., that man is not conscious. Furthermore, if one tried to accept that catch phrase, one would find that its second part contradicts its first: if nobody can be certain of anything, then everybody can be certain of everything he pleases—since it cannot be refuted, and he can claim he is not certain he is certain (which is the purpose of that notion).

Copyright © 1986 by Harry Binswanger. Introduction copyright © 1986 by Leonard Peikoff. All rights reserved. For information address New American Library.


Excerpts from The Ominous Parallels, by Leonard Peikoff. Copyright © 1982 by Leonard Peikoff. Reprinted with permission of Stein and Day Publishers. Excerpts from The Romantic Manifesto, by Ayn Rand. Copyright © 1971, by The Objectivist. Reprinted with permission of Harper & Row, Publishers, Inc. Excerpts from Atlas Shrugged, copyright © 1957 by Ayn Rand, The Fountainhead, copyright © 1943 by Ayn Rand, and For the New Intellectual, copyright © 1961 by Ayn Rand. Reprinted by permission of the Estate of Ayn Rand. Excerpts from Philosophy: Who Needs It, by Ayn Rand. Copyright © 1982 by Leonard Peikoff, Executor, Estate of Ayn Rand. Reprinted by permission of the Estate of Ayn Rand. Excerpts from “The Philosophy of Objectivism” lecture series. Copyright © 1976 by Leonard Peikoff. Reprinted by permission. Excerpts from Alvin Toffler’s interview with Ayn Rand, which first appeared in Playboy magazine. Copyright © 1964. Reprinted by permission of Alvin Toffler. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Plume, a member of Penguin Group (USA), Inc.