Let us now see if there be room in this philosophy for our argument from adaptability, and whether it will allow us to infer that because belief in theism and in future retribution are beliefs postulated by our higher moral aspirations, therefore they answer to reality more or less approximately; whether, in short, under certain conditions (specified in our last essay) the wish to believe may be a valid reason for believing.
Now Evolution as a philosophy or explanatory hypothesis owes its popularity to its apparent simplicity. Wrapped in its wordy envelope, the notion as formulated by Spencer needs no subtilty of apprehension, but only a dictionary. Nor is the Darwinian theory of Natural Selection more difficult.
Other things equal, the simpler hypothesis is to be preferred to the less simple where no proof can be had of either. But none the less, the simpler may be false and the other true. Cheapness is no proof of goodness. We are naturally impatient of troublesome and complex theories; but what we gain in the simplicity of an hypothesis, we commonly lose in the difficulty of getting the facts to square with it. It is a simple theory that circular motion is the most perfect, and that the planets being the most perfect bodies must move with the most perfect motion; but so many epicycles must be introduced to explain apparent exceptions that the modern astronomical hypothesis, however more complex in statement, is on the whole welcomed as a simplification. So we are disposed to think it is with regard to the popular form of Evolutionism. Its simplicity in statement is more than cancelled by its difficulty in application; and at last we are driven to conceive it in a form which at once deprives it of its title to popularity. So far as it is simple it is fallacious and proves incoherent on closer inspection, when we try to translate its terms into clear and distinct ideas; but when we get it into intelligible form it is no simpler than the theistic hypothesis which it wants to displace, except inasmuch as it prescinds from the question of origin and last end. But in this, its only intelligible form, it leaves the argument from adaptability intact, and even requires theism as its rational complement.
This is what we must now endeavour to show. We cannot illustrate our contention better than from the popular simplification of Ethics introduced by Bentham. Taking pleasure as a simple and ultimate notion he affirms that our conduct is always determined by a balance of pleasure on one side or the other. The problem of practical ethics is to construct a calculus of pleasures, a sort of ready-reckoner whereby men may be able to invest in the most profitable course of action. "When we have a hedonistic calculus with its senior wranglers," says Mr. Bain, "we shall begin to know whether society admits of being properly reconstructed." [5] It is assumed that pleasures differ only in quantity, i.e., in intensity, extent, and duration, just as warmth does, which may be of high or low temperature; diffused over a greater or less extent of body; and that, for a shorter or a longer time. On this assumption pleasure is every bit as mathematically measurable as is warmth, the whole difficulty being due to its subjective and therefore inaccessible nature. Simple in statement, this theory proves in application infinitely complex, and indeed on closer inspection breaks up into a mere verbal fallacy—as Dr. Martineau, amongst others, has shown in his Types of Ethical Theory. For "pleasure," though one simple word, has an endless variety of meanings, not indeed wholly disconnected, but bound together only by a certain kind of analogy. The eye, the ear, the palate, the mind, the heart, have each their proper pleasure; which is nothing else than the resultant of their perfect operation in response to the stimulus of some all-satisfying object—a fact which may be expressed differently by different philosophies, but with substantial identity of meaning. But not till we find some common measure for sound and colour and flavour and thought and affection, will it be possible to compare in any hedonistic scales the pleasures they produce. Yet colour is to the eye what music is to the ear; and therefore the one word pleasure is used not unreasonably of both.
Quite similar seems to us the fallacy to which Evolution owes its seeming simplicity and its popularity. The word "existence" or "life" (which is the existence of organic beings, about which we are chiefly concerned), is taken as having one homogeneous meaning, like "heat" or "warmth;" the only difference being quantitative—a difference of intensity, of breadth, of duration; not a difference of kind such as would destroy all common measure. Life is something which we predicate of the most diversely organized beings, and therefore would seem to be something the same in all, which they secure in a diversity of ways.
Thus Darwin defines the general good or welfare which should be the aim of our conduct as "the rearing of the greatest number of individuals in full health and vigour with all their faculties perfect;" upon which Mr. Sidgwick remarks[6] with justice: "Such a reduction of the notion of 'well-being' to 'being' (actual and potential) would be a most important contribution from the doctrine of Evolution to ethical science. But it at least conflicts in a very startling manner with those ordinary notions of progress and development" in which "it is always implied that certain forms of life are qualitatively superior to others, independently of the number of individuals, present or future, in which each form is realized…. And if we confine ourselves to human beings, to whom alone the practical side of the doctrine applies, is it not too paradoxical to assert that 'rising in the scale of existence' means no more than 'developing the capacity to exist'? A greater degree of fertility would thus become an excellence outweighing the finest moral and intellectual endowments; and some semi-barbarous races must be held to have attained the end of human existence more than some of the pioneers and patterns of civilization." Nor is it only in the region of ethics but in every region that this false simplification is fertile in paradoxes; and yet if it be disowned, the charm to which Evolution owes its popularity is gone.
It would be indeed a short cut to knowledge if we might believe life to be, as this theory imagines it, a simple, self-diffusing force with an irrepressible tendency to spread itself in all directions, like fire in a prairie. True we should not have altogether got rid of innate tendencies, but we should have reduced them to one, namely, to the struggling, or persisting, or self-asserting tendency; a simplification like that offered by the matter-and-force theory of Buchner.
This flame of life once kindled (we are told) endeavours to subdue all things to itself, and all that we find in the way of variety of organic structure and function has been shaped and determined by its struggle—much as a river channels a way for its waters in virtue of its own onward force, checked and determined by the nature of the obstacles it has to encounter. Every organism is related to life as the candlestick to the candle; it is simply a device for supporting and spreading as much life as is possible with the surrounding conditions. Often, when conditions are favourable, the simplest contrivance will be more effectual, more life-producing than the most complex in less favourable conditions. Where food is not present the animal that can move about in search of it will survive, and the stationary animal perish; and likewise those that can escape their foes will live down those rooted in one spot. And if to motion we add perception and intelligence, and associative instincts and the rest, we increase the appliances for dealing with difficulties; and therewith the means of survival when such difficulties exist. Still, in the hypothesis we are dealing with, all these contrivances—movement, consciousness, intelligence, will, society—are distinct from life and ministerial to it; they are instruments by which it is preserved, increased, and multiplied—like those contrivances by which heat or electricity is generated, sustained, and transmitted; with this difference, that no one has designed these life-machines, but they are simply the result of life's innate tendency to struggle and spread. A great deal of the form and movement of the inorganic world is due simply to the stress of gravitation and not to design, and so we are asked to believe that the human and every other organism has been shaped and quickened by the action of as blind a power; that it is in some sense a casual result.
Now if seeing and hearing and thinking do not constitute life, but are only chance discoveries helpful to life; if we do not live in order to eat and to see and to think, but only think, see, and eat in order to live, we ask ourselves, what then is this life which is none of these things and to which they are all subordinate? And when once we begin subtracting those functions which minister to life and which life has selected for its own service, we find there is absolutely nothing left to serve. Taking the very earliest forms, if we subtract movement, nutrition, growth, generation, we find there is nothing over called "life" distinct from these. This is the first and fundamental incoherence of the theory; life has simply no meaning apart from those functions which we speak of as ministering to life; unless we mean by life the mere cohering together of the bodily organism—an end more effectually secured without any such complex apparatus, by a stone or by an elementary atom.
If existence in that sense, be the force or principle whose persistence and self-assertion is the cause of all evolution, it is impossible to conceive how primordial atoms, which are assumed to be indestructible and constant in quantity, should trouble themselves to struggle at all; since the amount of that kind of existence can neither be lessened nor increased. And as motion is also assumed to be a constant quantity, it is plain that what struggles to be and to multiply, must be some special collocation and grouping of atoms with some correspondingly particular determination of motion, called "life;" but what "life" is, apart from the means it is supposed to have selected for itself, does not appear.