The only adequate disproof of the position here maintained would be about as follows.  Let a Japanese infant be reared in an American home from infancy, not only fed and clothed as an American, but loved as a member of the family and trained as carefully and affectionately as one’s own child.  The full conditions require that not only the child himself, but everyone else, be ignorant of his parentage and race in order that he be thought to be, and be treated as though he were, a genuine member of his adopting home and people.  What would be the psychic characteristics of that child when grown to manhood?  If he should manifest psychic traits like those of his Japanese parents, if he should think in the Japanese order, if he should have a tendency to use prepositions as postpositions, if he should drop pronouns and should use honorific words in their place, if he should be markedly suspicious and inferential, if he should bow in making his salutations rather than shake hands, if he should show marked preference for sitting on the floor rather than on chairs, and for chopsticks to knives and forks, and if developing powers as an artist he should naturally paint Japanese pictures, Japanese landscapes, and Japanese faces, finding himself unable to draw according to the canons of Western art, if on developing poetic tastes he should find special pleasure in seventeen syllable or thirty-one syllable exclamatory poems, finding little interest in Longfellow or Shakespeare, if, in short, he should develop a predilection for any distinctive Japanese custom, habit of thought, method of speech, emotion or volition, it would evidently be due to his intrinsic heredity.  If in all these matters, however, he should prove to be like an American, acquiring an American education like any American boy, and if on being brought to Japan, at, say, thirty years of age, still supposing himself to be an American, he should have equal difficulty with any American in mastering the language and adapting himself to and understanding the Japanese people, then it would follow that his psychic characteristics have been inherited socially and he is what he is, nationally, because of his social heritage.  Such a result would show that the psychic traits differentiating races are social and not intrinsic.

We have limited our discussion to the advanced races because the problem is then relatively simple, the material abundant, and the issue clear.  Much discussion in theology, psychology, and sociology is futile because it concerns that practically mythical being, the aboriginal man, about whose social and psychic life no one knows anything, and any theorizer can say what he chooses without fear of shipwreck on incontrovertible facts.  Whether the lowest races known to-day are differentiated from the highest only by acquired social and psychic characteristics, or also by differences of psychic nature, may perhaps be an open question.  However this may be, the case is fairly clear in regard to the higher races inhabiting the earth.  Their differentiating psychic characteristics are, for the most part, not due to diverse psychic nature, but to diverse social orders, while the transmission of these characteristics takes place, as a matter of observation, through social heredity.