species. Now, the trouble is not irrationality, not a definite preference for unreason, but suggestibility—that is, a capacity for accepting reason or unreason if it comes from the proper source.
This quality we have seen to be a direct consequence of the social habit, of a single definite instinct, that of gregariousness, the same instinct which makes social life at all possible and altruism a reality.
It does not seem to have been fully understood that if you attack suggestibility by selection—and that is what you do if you breed for rationality—you are attacking gregariousness, for there is at present no adequate evidence that the gregarious instinct is other than a simple character and one which cannot be split up by the breeder. If, then, such an effort in breeding were successful, we should exchange the manageable unreason of man for the inhuman rationality of the tiger.
The solution would seem rather to lie in seeing to it that suggestion always acts on the side of reason; if rationality were once to become really respectable, if we feared the entertaining of an unverifiable opinion with the warmth with which we fear using the wrong implement at the dinner table, if the thought of holding a prejudice disgusted us as does a foul disease, then the dangers of man’s suggestibility would be turned into advantages. We {46} have seen that suggestion already has begun to act on the side of reason in some small part of the life of the student of science, and it is possible that a highly sanguine prophetic imagination might detect here a germ of future changes.
Again, a fourth corollary of gregariousness in man is the fact expounded many years ago by Pearson that human altruism is a natural instinctive product. The obvious dependence of the evolution of altruism upon increase in knowledge and inter-communication has led to its being regarded as a late and a conscious development—as something in the nature of a judgment by the individual that it pays him to be unselfish.