We need not, however, for our present purpose, attempt to ascertain how the distinctively emotional characteristics arise. It is sufficient that they are presumably present in the situation. Now, as Dr. Stout well points out,[186] the emotions generally presuppose the existence of certain specific tendencies. “The anger produced in a dog by taking away its bone presupposes the specific appetite for food. The anger produced in it by interfering with its young presupposes the specific tendency to guard and tend its offspring. So the presence of a rival who interferes with its wooing causes anger because of the pre-existence of the sexual impulse.” In general, we may say that emotional states are, under natural conditions, closely associated with behaviour of biological value--with tendencies which are beneficial in self-preservation or race-preservation--with actions that promote survival, and especially with the behaviour which clusters round the pairing and parental instincts. The value of the emotions in animals is that they are an indirect means of furthering survival. But how has the close association between emotional condition and the biological end it furthers been established? Again, we must say that under natural conditions it is not the sort of thing which could be acquired. And again we must urge that natural selection through survival is, apart from some theory of pre-established harmony, the only hypothesis in the field on which the close association can be explained.
There is one more point to which attention may be drawn. If there be one thing, and there certainly are not many, on which all writers on the emotions are agreed, it is as to their vagueness. They do not readily submit to definition, and cannot be described in a sentence. This is not due to any indefiniteness of biological end, nor to much indefiniteness in the mode of “expression;” it is due, rather, to an inherent dimness and haziness of psychological outline. We seem unable to focus them and get a clear-cut result. This is, no doubt, in part due to the complexity of emotional states. But, may it not be largely due to the fact that there is no necessity for definiteness? They fulfil their purpose just as well if they are vague. It is quite necessary for the dog to have a clear-cut impression of his antagonist; and, on the cognitive side of consciousness, meaning must be in some degree definite to be of real value. But, so long as the emotion raises the temperature, so to speak, to the boiling-point of vigorous action, it matters little what the psychological source of heat may be. If this be so, we should expect an emotional vagueness, since natural selection puts no premium upon emotional definiteness. And from this it follows, as a corollary, that, whereas we may infer that an animal’s perceptual products are probably closely similar to our own, since sight, touch, hearing, smell, and taste are of value in so far as they convey definite meaning, in interpreting their feelings and emotions we have less secure grounds of inference, since all that is requisite is that there should be a sufficiently high emotional temperature to afford the conditions for definite and vigorous action.