§2. Let us pass to consider the notions `Nature', `Natural', `Conformity to Nature'. I assume---in order to obtain a principle distinct from `Self-realisation',---that the `Nature' to which we are to conform is not each one's own individual nature, but human nature generally, considered either apart from or in relation to its environment: that we are to find the standard of right conduct in a certain type of human existence which we can somehow abstract from observation of actual human life. Now in a certain sense every rational man must, of course, ``conform to nature''; that is, in aiming at any ends, he must adapt his efforts to the particular conditions of his existence, physical and psychical. But if he is to go beyond this, and conform to `Nature' in the adoption of an ultimate end or paramount standard of right conduct, it must be on the basis---if not of strictly Theological assumptions, at any rate---of the more or less definite recognition of Design exhibited in the empirically known world. If we find no design in nature, if the complex processes of the world known to us through experience are conceived as an aimless though orderly drift of change, the knowledge of these processes and their laws may indeed limit the aims of rational beings, but I cannot conceive how it can determine the ends of their action, or be a source of unconditional rules of duty. And in fact those who use `natural' as an ethical notion do commonly suppose that by contemplating the actual play of human impulses, or the physical constitution of man, or his social relations, we may find principles for determining positively and completely the kind of life he was designed to live. I think, however, that every attempt thus to derive `what ought to be' from `what is' palpably fails, the moment it is freed from fundamental confusions of thought. For instance, suppose we seek practical guidance in the conception of human nature regarded as a system of impulses and dispositions, we must obviously give a special precision to the meaning of ``natural''; since in a sense, as Butler observes, any impulse is natural, but it is manifestly idle to bid us follow Nature in this sense: for the question of duty is never raised except when we are conscious of a conflict of impulses, and wish to know which to follow. Nor does it help us to say that the supremacy of Reason is Natural, as we have started by assuming that what Reason prescribes is conformity to Nature, and thus our line of thought would become circular: the Nature that we are to follow must be distinguished from our Practical Reason, if it is to become a guide to it. How then are we to distinguish `natural impulses'---in the sense in which they are to guide rational choice---from the unnatural? Those who have occupied themselves with this distinction seem generally to have interpreted the Natural to mean either the common as opposed to the rare and exceptional, or the original as opposed to what is later in development; or, negatively, what is not the effect of human volition. But I have never seen any ground for assuming broadly that Nature abhors the exceptional, or prefers the earlier in time to the later; and when we take a retrospective view of the history of the human race, we find that some impulses which all admire, such as the love of knowledge and enthusiastic philanthropy, are both rarer and later in their appearance than others which all judge to be lower. Again, it is obviously unwarrantable to eschew as unnatural and opposed to the Divine design all such impulses as have been produced in us by the institutions of society, or our use of human arrangements and contrivances, or that result in any way from the deliberate action of our fellow-men: for this were arbitrarily to exclude society and human action from the scope of Nature's purposes. And besides it is clear that many impulses so generated appear to be either moral or auxiliary to morality and in other ways beneficial: and though others no doubt are pernicious and misleading, it seems that we can only distinguish these latter from the former by taking note of their effects, and not by any precision that reflection can give to the notion of `natural'. If, again, we fall back upon a more physical view of our nature and endeavour to ascertain for what end our corporeal frame was constructed, we find that such contemplation determines very little. We can infer from our nutritive system that we are intended to take food, and similarly that we are to exercise our various muscles in some way or other, and our brain and organs of sense. But this carries us a very trifling way, for the practical question almost always is, not whether we are to use our organs or leave them unused, but to what extent or in what manner we are to use them: and it does not appear that a definite answer to this question can ever be elicited, by a logical process of inference, from observations of the human organism, and the actual physical life of men.
If, finally, we consider man in his social relations---as father, son, neighbour, citizen---and endeavour to determine the ``natural'' rights and obligations that attach to such relations, we find that the conception `natural' presents a problem and not a solution. To an unreflective mind what is customary in social relations usually appears natural; but no reflective person is prepared to lay down ``conformity to custom'' as a fundamental moral principle: the problem, then, is to find in the rights and obligations established by custom in a particular society at a particular time an element that has a binding force beyond what mere custom can give. And this problem can only be solved by reference to the ultimate good of social existence---whether conceived as happiness or as perfection---or by appealing to some intuitively known principle of social duty, other than the principle of aiming at the happiness or perfection of society.
Nor, again, does it help us to adopt the more modern view of Nature, which regards the organic world as exhibiting, not an aggregate of fixed types, but a continuous and gradual process of changing life. For granting that this `evolution'---as the name implies---is not merely a process from old to new, but a progress from less to more of certain definite characteristics; it is surely absurd to maintain that we ought therefore to take these characteristics as Ultimate Good, and make it our whole endeavour to accelerate the arrival of an inevitable future. That whatever is to be will be better than what is, we all hope; but there seems to be no more reason for summarily identifying `what ought to be' with `what certainly will be', than for finding it in `what commonly is', or `what originally was'.
On the whole, it appears to me that no definition that has ever been offered of the Natural exhibits this notion as really capable of furnishing an independent ethical first principle. Arid no one maintains that `natural' like `beautiful' is a notion that though indefinable is yet clear, being derived from a simple unanalysable impression. Hence I see no way of extracting from it a definite practical criterion of the rightness of actions.