Nor, again, is the complexity of the adjustment distinctive of intelligence as opposed to instinct. The case of the sitaris, before given, the larva of which attaches itself to a male bee, passes on to the female, springs upon the eggs she lays, eats first the egg and then the store of honey,—this case, I say, affords us a series of sufficiently marked complexity. This instinct, the paralyzing, but not killing outright, of prey by the sphex; the marvellous economy of wax in the cell-building of the honey-bee; the affixing to their body, by crabs, of seaweed (Stenorhynchus), of ascidians (an Australian Dromia), of sponge (Dromia vulgaris), of the cloaklet anemone (Pagurus prideauxii); and other cases too numerous for citation;—these show, too, that the circumstances may be dealt with in such a way as to extract from them the maximum of benefit, probably without intelligence. It would be quite impossible intelligently to improve upon the manner of dealing with the circumstances displayed in many instinctive activities, even those which we have reason to believe were evolved without the co-operation of intelligence.
There remain, therefore, the novelty of the adjustment and the individuality displayed in these adjustments. And here we seem to have the essential features of intelligent activities. The ability to perform acts in special adaptation to special circumstances, the power of exercising individual choice between contradictory promptings, and the individuality or originality manifested in dealing with the complex conditions of an ever-changing environment,—these seem to be the distinctive features of intelligence. On the other hand, in instinctive actions there seems to be no choice; the organism is impelled to their performance through impulse, as by a stern necessity; they are so far from novel that they are performed by every individual of the species, and have been so performed by their ancestors for generations; and, in performing the instinctive action, the animal seems to have no more individuality or originality than a piece of adequately wound clockwork.
It may be said that, in granting to animals a power of individual choice, we are attributing to them free-will; and surely (it may be added), after denying to them reason, we cannot, in justice and in logic, credit them with this, man's choicest gift. I shall not here enter into the free-will controversy. I shall be content with defining what I mean by saying that animals have a power of individual choice. Two weather-cocks are placed on adjoining church pinnacles, two clouds are floating across the sky, two empty bottles are drifting down a stream. None of these has any power of individual choice. They are completely at the mercy of external circumstances. On the other hand, two dogs are trotting down the road, and come to a point of divergence; one goes to the right hand, the other to the left hand. Here each exercises a power of individual choice as to which way he shall go. Or, again, my brother and I are out for a walk, and our father's dog is with us. After a while we part, each to proceed on his own way. Pincher stands irresolute. For a while the impulse to follow me and the impulse to follow my brother are equal. Then the former impulse prevails, and he bounds to my side. He has exercised a power of individual choice. If any one likes to call this yielding to the stronger motive an exercise of free-will, I, for one, shall not say him nay. What I wish specially to notice about it is that we have here a sign of individuality. There is no such individuality in inorganic clouds or empty bottles. Choice is a symbol of individuality; and individuality is a sign of intelligence.
But though I decline here to enter into the free-will controversy, I may fairly be asked where I place volition in the series between external stimulus and resulting activity; and what I regard as the concomitant physiological manifestation. I doubt whether I shall be able to say anything very satisfactory in answer to these questions. I shall have to content myself with little more than stating how the problem presents itself to my mind.
I believe that volition is intimately bound up and associated with inhibition. I go so far as to say that, without inhibition, volition properly so called has no existence. When the series follows the inevitable sequence—
Stimulus: perception: emotion: fulfilment in action
—the act is involuntary. And such it must ever have remained, had not inhibition been evolved, had not an alternative been introduced, thus—
| Stimulus: perception: emotion | / | fulfilment in action. |
| \ | inhibition of action. |
At the point of divergence I would place volition. Volition is the faculty of the forked way. There are two possibilities—fulfilment in action or inhibition. I can write or I can cease writing; I can strike or I can forbear. And my poor little wounded terrier, whose gashed side I was sewing up, clumsily, perhaps, but with all the gentleness and tenderness I could command, could close his teeth on my hand or could restrain the action.
I have here, so to speak, reduced the matter to its simplest expression. It is really more complex. For volition involves an antagonism of motives, one or more prompting to action, one or more prompting to restraint. The organism yields to the strongest prompting, acts or refrains from acting according as one motive or set of motives or the other motive or set of motives prevails; in other words, according as the stimuli to action or the inhibitory stimuli are the more powerful.