“Rand's Razor”

The requirements of cognition determine the objective criteria of conceptualization. They can be summed up best in the form of an epistemological “razor”: concepts are not to be multiplied beyond necessity—the corollary of which is: nor are they to be integrated in disregard of necessity.

The requirements of cognition forbid the arbitrary grouping of existents, both in regard to isolation and to integration. They forbid the random coining of special concepts to designate any and every group of existents with any possible combination of characteristics. For example, there is no concept to designate “Beautiful blondes with blue eyes, 5’5” tall and 24 years old.” Such entities or groupings are identified descriptively. If such a special concept existed, it would lead to senseless duplication of cognitive effort (and to conceptual chaos): everything of significance discovered about that group would apply to all other young women as well. There would be no cognitive justification for such a concept—unless some essential characteristic were discovered, distinguishing such blondes from all other women and requiring special study, in which case a special concept would become necessary. . . .

In the process of determining conceptual classification, neither the essential similarities nor the essential differences among existents may be ignored, evaded or omitted once they have been observed. Just as the requirements of cognition forbid the arbitrary subdivision of concepts, so they forbid the arbitrary integration of concepts into a wider concept by means of obliterating their essential differences—which is an error (or falsification) proceeding from definitions by non-essentials. (This is the method involved in the obliteration of valid concepts by means of “anti-concepts.”)

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.