To argue that a thing is good because it is natural, or bad because it is unnatural, in these common senses of the term, is therefore certainly fallacious; and yet such arguments are very frequently used. But they do not commonly pretend to give a systematic theory of Ethics. Among attempts to systematise an appeal to nature, that which is now most prevalent is to be found in the application to ethical questions of the term Evolution—in the ethical doctrines which have been called Evolutionistic. These doctrines are those which maintain that the course of evolution, while it shews us the direction in which we are developing, thereby and for that reason shews us the direction in which we ought to develop. Writers, who maintain such a doctrine, are at present very numerous and very popular; and I propose to take as my example the writer, who is perhaps best known of them all—Mr Herbert Spencer. Mr Spencer’s doctrine, it must be owned, does not offer the clearest example of the naturalistic fallacy as used in support of Evolutionistic Ethics. A clearer example might be found in Guyau, a writer who has lately had considerable vogue in France, but who is not so well known as Spencer. Guyau might almost be called a disciple of Spencer; he is frankly evolutionistic, and frankly naturalistic; and I may mention that he does not seem to think that he differs from Spencer by reason of his naturalism. The point in which he has criticised Spencer concerns the question how far the ends of pleasure and of increased life coincide as motives and means to the attainment of the ideal: he does not seem to think that he differs from Spencer in the fundamental principle that the ideal is Quantity of life, measured in breadth as well as in length, or, as Guyau says, Expansion and intensity of life; nor in the naturalistic reason which he gives for this principle. And I am not sure that he does differ from Spencer in these points. Spencer does, as I shall shew, use the naturalistic fallacy in details; but with regard to his fundamental principles, the following doubts occur: Is he fundamentally a Hedonist? And, if so, is he a naturalistic Hedonist? In that case he would better have been treated in my next chapter. Does he hold that a tendency to increase quantity of life is merely a criterion of good conduct? Or does he hold that such increase of life is marked out by nature as an end at which we ought to aim? (§ 29 ¶ 1)

I think his language in various places would give colour to all these hypotheses; though some of them are mutually inconsistent. I will try to discuss the main points. (§ 29 ¶ 2)

The modern vogue of Evolution is chiefly owing to Darwin’s investigations as to the origin of species. Darwin formed a strictly biological hypothesis as to the manner in which certain forms of animal life became established, while others died out and disappeared. His theory was that this might be accounted for, partly at least, in the following way. When certain varieties occurred (the cause of their occurrence is still, in the main, unknown), it might be that some of the points, in which they have varied from their parent species or from other species then existing, made them better able to persist in the environment in which they found themselves—less liable to be killed off. They might, for instance, be better able to endure the cold or heat or changes of the climate; better able to find nourishment from what surrounded them; better able to escape from or resist other species which fed upon them; better fitted to attract or master the other sex. Being thus liable to die, their numbers relatively to other species would increase; and that very increase in their numbers might tend towards the extinction of those other species. This theory, to which Darwin gave the name Natural Selection, was also called the theory of survival of the fittest. The natural process which it thus described was called evolution. It was very natural to suppose that evolution meant evolution from what was lower into what was higher; in fact it was observed that at least one species, commonly called higher—the species man—had so survived, and among men again it was supposed that the higher races, ourselves for example, had shewn a tendency to survive the lower, such as the North American Indians. We can kill them more easily than they can kill us. The doctrine of evolution was then represented as an explanation of how the higher species survives the lower. Spencer, for example, constantly uses more evolved as equivalent to higher. But it is to be noted that this forms no part of Darwin’s scientific theory. That theory will explain, equally well, how by an alteration in the environment (the gradual cooling of the earth, for example), quite a different species from man, a species which we think infinitely lower, might survive us. The survival of the fittest does not mean, as one might suppose, the survival of what is fittest to fulfil a good purpose—best adapted to a good end: at the last, it means merely the survival of the fittest to survive; and the value of the scientific theory, and it is a theory of great value, just consists in shewing what are the causes which produce certain biological effects. Whether these effects are good or bad, it cannot pretend to judge. (§ 30 ¶ 1)

But now let us hear what Mr Spencer says about the application of Evolution to Ethics. (§ 31 ¶ 1)

I recur, he says, to the main proposition set forth in these two chapters, which has, I think, been fully justified. Guided by the truth that as the conduct with which Ethics deals is part of conduct at large, conduct at large must be generally understood before this part can be specially understood; and guided by the further truth that to understand conduct at large we must understand the evolution of conduct; we have been led to see that Ethics has for its subject-matter, that form which universal conduct assumes during the last stages of its evolution. We have also concluded that these last stages in the evolution of conduct are those displayed by the highest type of being when he is forced, by increase of numbers, to live more and more in presence of his fellows. And there has followed the corollary that conduct gains ethical sanction in proportion as the activities, becoming less and less militant and more and more industrial, are such as do not necessitate mutual injury or hindrance, but consist with, and are furthered by, co-operation and mutual aid. (§ 31 ¶ 2)

These implications of the Evolution-Hypothesis, we shall now see harmonize with the leading moral ideas men have otherwise reached. (§ 31 ¶ 3)

Now, if we are to take the last sentence strictly—if the propositions which precede it are really thought by Mr Spencer to be implications of the Evolution-Hypothesis—there can be no doubt that Mr Spencer has committed the naturalistic fallacy. All that the Evolution-Hypothesis tells us is that certain kinds of conduct are more evolved than others; and this is, in fact, all that Mr Spencer has attempted to prove in the two chapters concerned. Yet he tells us that one of the things it has proved is that conduct gains ethical sanction in proportion as it displays certain characteristics. What he has tried to prove is only that, in proportion as it displays those characteristics, it is more evolved. It is plain, then, that Mr Spencer identifies the gaining of ethical sanction with the being more evolved: this follows strictly from his words. But Mr Spencer’s language is extremely loose; and we shall presently see that he seems to regard the view it here implies as false. We cannot, therefore, take it as Mr Spencer’s definite view that better means nothing but more evolved; or even that what is more evolved is therefore better. But we are entitled to urge that he is influenced by these views, and therefore by the naturalistic fallacy. It is only by the assumption of such influence that we can explain his confusion as to what he has really proved, and the absence of any attempt to prove, what he says he has proved, that conduct which is more evolved is better. We shall look in vain for any attempt to shew that ethical sanction is in proportion to evolution, or that it is the highest type of being which displays the most evolved conduct; yet Mr Spencer concludes that this is the case. It is only fair to assume that he is not sufficiently conscious how much these propositions stand in need of proof—what a very different thing is being more evolved from being higher or better. It may, of course, be true that what is more evolved is also higher and better. But Mr Spencer does not seem aware that to assert the one is in any case not the same thing as to assert the other. He argues at length that certain kinds of conduct are more evolved, and then informs us that he has proved them to gain ethical sanction in proportion, without any warning that he has omitted the most essential step in such a proof. Surely this is sufficient evidence that he does not see how essential that step is. (§ 31 ¶ 4)

Whatever be the degree of Mr Spencer’s own guilt, what has just been said will serve to illustrate the kind of fallacy which is constantly committed by those who profess to base Ethics on Evolution. But we must hasten to add that the view which Mr Spencer elsewhere most emphatically recommends is an utterly different one. It will be useful briefly to deal with this, in order that no injustice may be done to Mr Spencer. The discussion will be instructive partly from the lack of clearness, which Mr Spencer displays, as to the relation of this view to the evolutionistic one just described; and partly because there is reason to suspect that in this view also he is influenced by the naturalistic fallacy. (§ 32 ¶ 1)

We have seen that, at the end of his second chapter, Mr Spencer seems to announce that he has already proved certain characteristics of conduct to be a measure of its ethical value. He seems to think that he has proved this merely by considering the evolution of conduct; and he has certainly not given any such proof, unless we are to understand that more evolved is a mere synonym for ethically better. He now promises merely to confirm this certain conclusion by shewing that it harmonizes with the leading moral ideas men have otherwise reached. But, when we turn to his third chapter, we find that what he actually does is something quite different. He here asserts that to establish the conclusion Conduct is better in proportion as it is more evolved an entirely new proof is necessary. That conclusion will be false, unless a certain proposition, of which we have heard nothing so far, is true—unless it is true that life is pleasant on the whole. And the ethical proposition, for which he claims the support of the leading moral ideas of mankind, turns out to be that life is good or bad, according as it does, or does not, bring a surplus of agreeable feeling (§ 10). Here, then, Mr Spencer appears, not as an Evolutionist, but as a Hedonist, in Ethics. No conduct is better, because it is more evolved. Degree of evolution can at most be a criterion of ethical value; and it will only be that, if we can prove the extremely difficult generalisation that the more evolved is always, on the whole, the pleasanter. It is plain that Mr Spencer here rejects the naturalistic identification of better with more evolved; but it is possible that he is influenced by another naturalistic identification—that of good with pleasant. It is possible that Mr Spencer is a naturalistic Hedonist. (§ 32 ¶ 2)

Let us examine Mr Spencer’s own words. He begins this third chapter by an attempt to shew that we call good the acts conducive to life, in self or others, and bad those which directly or indirectly tend towards death, special or general (§ 9). And then he asks: Is there any assumption made in so calling them? Yes; he answers, an assumption of extreme significance has been made—an assumption underlying all moral estimates. The question to be definitely raised and answered before entering on any ethical discussion, is the question of late much agitated—Is life worth living? Shall we take the pessimist view? or shall we take the optimist view?… On the answer to this question depends every decision concerning the goodness or badness of conduct. But Mr Spencer does not immediately proceed to give the answer. Instead of this, he asks another question: But now, have these irreconcilable opinions [pessimist and optimist] anything in common? And this question he immediately answers by the statement: Yes, there is one postulate in which pessimists and optimists agree. Both their arguments assume it to be self-evident that life is good or bad, according as it does, or does not, bring a surplus of agreeable feeling (§ 10). It is to the defence of this statement that the rest of the chapter is devoted; and at the end Mr Spencer formulates his conclusion in the following words: No school can avoid taking for the ultimate moral aim a desirable state of feeling called by whatever name—gratification, enjoyment, happiness. Pleasure somewhere, at some time, to some being or beings, is an inexpugnable element of the conception (§ 16 ad fin.). (§ 33 ¶ 1)

Now in all this, there are two points to which I wish to call attention. The first is that Mr Spencer does not, after all, tell us clearly what he takes to be the relation of Pleasure and Evolution in ethical theory. Obviously he should mean that pleasure is the only intrinsically desirable thing; that other good things are good only in the sense that they are means to its existence. Nothing but this can properly be meant by asserting it to be the ultimate moral aim, or, as he subsequently says (§ 62ad fin.), the ultimately supreme end. And, if this were so, it would follow that the more evolved conduct was better than the less evolved, only because, and in proportion as, it gave more pleasure. But Mr Spencer tells us that two conditions are, taken together, sufficient to prove the more evolved conduct better: (1) That it should tend to produce more life; (2) That life should be worth living or contain a balance of pleasure. And the point I wish to emphasise is that if these conditions are sufficient, then pleasure cannot be the sole good. For though to produce more life is, if the second of Mr Spencer’s propositions be correct, one way of producing more pleasure, it is not the only way. It is quite possible that a small quantity of life, which was more intensely and uniformly present, should give a greater quantity of pleasure than the greatest possible quantity of life that was only just worth living. And in that case, on the hedonistic supposition that pleasure is the only thing worth having, we should have to prefer the smaller quantity of life and therefore, according to Mr Spencer, the less evolved conduct. Accordingly, if Mr Spencer is a true Hedonist, the fact that life gives a balance of pleasure is not, as he seems to think, sufficient to prove that the more evolved conduct is the better. If Mr Spencer means us to understand that it is sufficient, then his view about pleasure can only be, not that it is the sole good or ultimately supreme end, but that a balance of it is a necessary constituent of the supreme end. In short, Mr Spencer seems to maintain that more life is decidedly better than less, if only it give a balance of pleasure: and that contention is inconsistent with the position that pleasure is the ultimate moral aim. Mr Spencer implies that of two quantities of life, which gave an equal amount of pleasure, the larger would nevertheless be preferable to the less. And if this be so, then he must maintain that quantity of life or degree of evolution is itself an ultimate condition of value. He leaves us, therefore, in doubt whether he is not still retaining the Evolutionistic proposition, that the more evolved is better, simply because it is more evolved, alongside the Hedonistic proposition, that the more pleasant is better, simply because it is more pleasant. (§ 33 ¶ 2)

But the second question which we have to ask is: What reasons has Mr Spencer for assigning to pleasure the position which he does assign to it? He tells us, we saw, that the arguments both of pessimists and of optimists assume it to be self-evident that life is good or bad, according as it does, or does not, bring a surplus of agreeable feeling; and he betters this later by telling us that since avowed or implied pessimists, and optimists of one or other shade, taken together constitute all men, it results that this postulate is universally accepted (§ 16). That these statements are absolutely false is, of course, quite obvious: but why does Mr Spencer think them true? and, what is more important (a question which Mr Spencer does not distinguish too clearly from the last), why does he think the postulate itself to be true? Mr Spencer himself tells us his proof is that reversing the application of the words good and bad—applying the word good to conduct, the aggregate results of which are painful, and the word bad to conduct, of which the aggregate results are pleasurable—creates absurdities (§ 16). He does not say whether this is because it is absurd to think that the quality, which we mean by the word good, really applies to what is painful. Even, however, if we assume him to mean this, and if we assume that absurdities are thus created, it is plain he would only prove that what is painful is properly thought to be so far bad, and what is pleasant to be so far good: it would not prove at all that pleasure is the supreme end. There is, however, reason to think that part of what Mr Spencer means is the naturalistic fallacy: that he imagines pleasant or productive of pleasure is the very meaning of the word good, and that the absurdity is due to this. It is at all events certain that he does not distinguish this possible meaning from that which would admit that good denotes an unique indefinable quality. The doctrine of naturalistic Hedonism is, indeed, quite strictly implied in his statement that virtue cannot be defined otherwise than in terms of happiness (§ 13); and, though, as I remarked above, we cannot insist upon Mr Spencer’s words as a certain clue to any definite meaning, that is only because he generally expresses by them several inconsistent alternatives—the naturalistic fallacy being, in this case, one such alternative. It is certainly impossible to find any further reasons given by Mr Spencer for his conviction that pleasure both is the supreme end, and is universally admitted to be so. He seems to assume throughout that we must mean by good conduct what is productive of pleasure, and by bad what is productive of pain. So far, then, as he is a Hedonist, he would seem to be a naturalistic Hedonist. (§ 33 ¶ 3)

So much for Mr Spencer. It is, of course, quite possible that his treatment of Ethics contains many interesting and instructive remarks. It would seem, indeed, that Mr Spencer’s main view, that of which he is most clearly and most often conscious, is that pleasure is the sole good, and that to consider the direction of evolution is by far the best criterion of the way in which we shall get most of it; and this theory, if he could establish that amount of pleasure is always in direct proportion to amount of evolution and also that it was plain what conduct was more evolved, would be a very valuable contribution to the science of Sociology; it would even, if pleasure were the sole good, be a valuable contribution to Ethics. But the above discussion should have made it plain that, if what we want from an ethical philosopher is a scientific and systematic Ethics, not merely an Ethics professedly based on science; if what we want is a clear discussion of the fundamental principles of Ethics, and a statement of the ultimate reasons why one way of acting should be considered better than another—then Mr Spencer’s Data of Ethics is immeasurably far from satisfying these demands. (§ 33 ¶ 4)

It remains only to state clearly what is definitely fallacious in prevalent views as to the relation of Evolution to Ethics—in those views with regard to which it seems so uncertain how far Mr Spencer intends to encourage them. I propose to confine the term Evolutionistic Ethics to the view that we need only to consider the tendency of evolution in order to discover the direction in which we ought to go. This view must be carefully distinguished from certain others, which may be commonly confused with it. (1) It might, for instance, be held that the direction in which living things have hitherto developed is, as a matter of fact, the direction of progress. It might be held that the more evolved is, as a matter of fact, also better. And in such a view no fallacy is involved. But, if it is to give us any guidance as to how we ought to act in the future, it does involve a long and painful investigation of the exact points in which the superiority of the more evolved consists. We cannot assume that, because evolution is progress on the whole, therefore every point in which the more evolved differs from the less is a point in which it is better than the less. A simple consideration of the course of evolution will therefore, on this view, by no means suffice to inform us of the course we ought to pursue. We shall have to employ all the resources of a strictly ethical discussion in order to arrive at a correct valuation of the different results of evolution—to distinguish the more valuable from the less valuable, and both from those which are no better than their causes, or perhaps even worse. In fact it is difficult to see how, on this view—if all that be meant is that evolution has on the whole been a progress—the theory of evolution can give any assistance to Ethics at all. The judgment that evolution has been a progress is itself an independent ethical judgment; and even if we take it to be more certain and obvious than any of the detailed judgments upon which it must logically depend for confirmation, we certainly cannot use it as a datum from which to infer details. It is, at all events, certain that, if this had been the only relation held to exist between Evolution and Ethics, no such importance would have been attached to the bearing of Evolution on Ethics as we actually find claimed for it. (2) The view, which, as I have said, seems to be Mr Spencer’s main view, may also be held without fallacy. It may be held that the more evolved, though not itself the better, is a criterion, because a concomitant, of the better. But this view also obviously involves an exhaustive preliminary discussion of the fundamental ethical question what, after all, is better. That Mr Spencer entirely dispenses with such a discussion in support of his contention that pleasure is the sole good, I have pointed out; and that, if we attempt such a discussion, we shall arrive at no such simple result, I shall presently try to shew. If however the good is not simple, it is by no means likely that we shall be able to discover Evolution to be a criterion of it. We shall have to establish a relation between two highly complicated sets of data; and, moreover, if we had once settled what were goods, and what their comparative values, it is extremely unlikely that we should need to call in the aid of Evolution as a criterion of how to get the most. It is plain, then, again, that if this were the only relation imagined to exist between Evolution and Ethics, it could hardly have been thought to justify the assignment of any importance in Ethics to the theory of Evolution. Finally, (3) it may be held that, though Evolution gives us no help in discovering what results of our efforts will be best, it does give some help in discovering what it is possible to attain and what are the means to its attainment. That the theory really may be of service to Ethics in this way cannot be denied. But it is certainly not common to find this humble, ancillary bearing clearly and exclusively assigned to it. In the mere fact, then, that these non-fallacious views of the relation of Evolution to Ethics would give so very little importance to that relation, we have evidence that what is typical in the coupling of the two names is the fallacious view to which I propose to restrict the name Evolutionistic Ethics. This is the view that we ought to move in the direction of evolution simply because it is the direction of evolution. That the forces of Nature are working on that side is taken as a presumption that it is the right side. That such a view, apart from metaphysical presuppositions, with which I shall presently deal, is simply fallacious, I have tried to shew. It can only rest on a confused belief that somehow the good simply means the side on which Nature is working. And it thus involves another confused belief which is very marked in Mr Spencer’s whole treatment of Evolution. For, after all, is Evolution the side on which Nature is working? In the sense, which Mr Spencer gives to the term, and in any sense in which it can be regarded as a fact that the more evolved is higher, Evolution denotes only a temporary historical process. That things will permanently continue to evolve in the future, or that they have always evolved in the past, we have not the smallest reason to believe. For Evolution does not, in this sense, denote a natural law, like the law of gravity. Darwin’s theory of natural selection does indeed state a natural law: it states that, given certain conditions, certain results will always happen. But Evolution, as Mr Spencer understands it and as it is commonly understood, denotes something very different. It denotes only a process which has actually occurred at a given time, because the conditions at the beginning of that time happened to be of a certain nature. That such conditions will always be given, or have always been given, cannot be assumed; and it is only the process which, according to natural law, must follow from these conditions and no others, that appears to be also on the whole a progress. Precisely the same natural laws—Darwin’s, for instance—would under other conditions render inevitable not Evolution—not a development from lower to higher—but the converse process, which has been called Involution. Yet Mr Spencer constantly speaks of the process which is exemplified by the development of man as if it had all the augustness of a universal Law of Nature: whereas we have no reason to believe it other than a temporary accident, requiring not only certain universal natural laws, but also the existence of a certain state of things at a certain time. The only laws concerned in the matter are certainly such as, under other circumstances, would allow us to infer, not the development, but the extinction of man. And that circumstances will always be favourable to further development, that Nature will always work on the side of Evolution, we have no reason whatever to believe. Thus the idea that Evolution throws important light on Ethics seems to be due to a double confusion. Our respect for the process is enlisted by the representation of it as the Law of Nature. But, on the other hand, our respect for Laws of Nature would be speedily diminished, did we not imagine that this desirable process was one of them. To suppose that a Law of Nature is therefore respectable, is to commit the naturalistic fallacy; but no one, probably, would be tempted to commit it, unless something which is respectable, were represented as a Law of Nature. If it were clearly recognised that there is no evidence for supposing Nature to be on the side of the Good, there would probably be less tendency to hold the opinion, which on other grounds is demonstrably false, that no such evidence is required. And if both false opinions were clearly seen to be false, it would be plain that Evolution has very little indeed to say to Ethics. (§ 34 ¶ 1)