The role of symbols in human behavior.

M DEFINITIONS Of "man" have been proposed by serious thinkers-proposed with the best intentions to call attention to a feature of man's existence which is crucial, the essence of humanness, as it were . If only man could say what man is, it was felt, man could understand man, and thus achieve Socrates' criterion of wisdom-self-knowledge . And so man has been called a featherless biped, a rational animal, a copy of God, a combination of body and soul, and a possessor of "free will ." Yet man's self-knowledge did not make much headway even amid an abundance of definitions. Except for the facetious "featherless biped" label, which, as N . Wiener remarked, made man indistinguishable from a kangaroo or a plucked chicken, none of the definitions pointed to anything which could be unambiguously recognized . One cannot identify rationality, observe God, isolate the soul, or test the existence of a "free will ." The first significant definitions of man were given by those philosophers who recognized that significant definitions should be given in terms of what the thing defined does rather than in terms of what it is . Such definitions are called operational. They call attention to actual events or experiences characteristic of the thing defined . I will say more about operational definitions in a while . To my knowledge, the first operational definitions of man were given by John Dewey and Alfred Korzybski about 1920 . They both defined man by his most characteristic and unique observable activity, namely, the preservation of past experience, not only in individuals but also in the species . As far as is known, no other species possesses a store of knowledge which is transmitted to successive generations by other than genetic means and accumulated in the process of transmission . This process of transmitting accumulated knowledge, which Korzybski called "time-binding," is accomplished by the use of symbols . Since the use of symbols, like time-binding, is also a crucial and unique characteristic of man, it is proper to call man a symbol-user and to make the study o f the symbolic process central to the study of man . A symbol can be most vividly defined by contrast with another form of communication called a signal . By a signal I mean nothing more than a stimulus to which a response has been conditioned . Thus to a dog the sound of