[B] This introspectual quality of the “_a priori_ synthesis of the most perfect sort” is found, for example, in the assumptions upon which is based the bulk of opinion in matters of Church and State, the family, justice, probity, honour, purity, crime, and so forth. Yet clearly we cannot say that there is a specific instinct concerned with each of these subjects, for that, to say the least, would be to postulate an unimaginable multiplicity of instincts, for the most part wholly without any conceivable biological usefulness. For example, there are considerable difficulties in imagining an instinct for making people Wesleyans or Roman Catholics, or an instinct for making people regard British family life as the highest product of civilization, yet there can be no question that these positions are based upon assumptions having all the characters described by James as belonging to the impulses of instinct.
Many attempts have been made to explain the behaviour of man as dictated by instinct. He is, in fact, moved by the promptings of such obvious instincts as self-preservation, nutrition, and sex enough to render the enterprise hopeful and its early spoils enticing. So much can so easily be generalized under these three impulses that the temptation to declare that all human behaviour could be resumed under them was irresistible. These early triumphs of materialism soon, however, began to be troubled by doubt. Man, in spite of his obvious duty to the contrary, would continue so often not to preserve himself, not to nourish himself and to prove resistant to the blandishments of sex, that the attempt to squeeze his behaviour into these three categories began to involve an increasingly obvious and finally intolerable amount of pushing and pulling, as well as so much pretence that he was altogether “in,” { 17} when, quite plainly, so large a part of him remained “out,” that the enterprise had to be given up, and it was once more discovered that man escaped and must always escape any complete generalization by science.
A more obvious inference would have been that there was some other instinct which had not been taken into account, some impulse, perhaps, which would have no very evident object as regarded the individual, but would chiefly appear as modifying the other instincts and leading to new combinations in which the primitive instinctive impulse was unrecognizable as such. A mechanism such as this very evidently would produce a series of actions in which uniformity might be very difficult to recognize by direct observation, but in which it would be very obvious if the characters of this unknown “x” were available.