In The Abolition of Man, C. S. Lewis addresses the issue of whether (evolved) instincts can provide any guidance whatsoever in the realm of value judgments or moral determinations (pp. 48–49):
Telling us to obey instinct is like telling us to obey ‘people’. People say different things: so do instincts. Our instincts are at war. If it is held that the instinct for preserving the species should always be obeyed at the expense of other instincts, whence do we derive this rule of precedence? To listen to that instinct speaking in its own cause and deciding in its own favour would be rather simple minded. Each instinct, if you listen to it, will claim to be gratified at the expense of all the rest. By the very act of listening to one rather than to others we have already prejudged the case. If we did not bring to the examination of our instincts a knowledge of their comparative dignity we could never learn it from them. And that knowledge cannot itself be instinctive: the judge cannot be one of the parties judged: or, if he is, the decision is worthless and there is no ground for placing the preservation of the species above self-preservation or sexual appetite.
The idea that, without appealing to any court higher than the instincts themselves, we can yet find grounds for preferring one instinct above its fellows dies very hard. We grasp at useless words: we call it the ‘basic’, or ‘fundamental’, or ‘primal’, or ‘deepest’ instinct. It is of no avail. Either these words conceal a value judgement passed upon the instinct and therefore not derivable from it, or else they merely record its felt intensity, the frequency of its operation, and its wide distribution. If the former, the whole attempt to base value upon instinct has been abandoned: if the latter, these observations about the quantitative aspects of a psychological event lead to no practical conclusion. It is the old dilemma. Either the premisses already concealed an imperative or the conclusion remains merely in the indicative.
He then inserts this priceless footnote:
The desperate expedients to which a man can be driven if he attempts to base value on fact are well illustrated by Dr C. H. Waddington’s fate in Science and Ethics. Dr Waddington here explains that ‘existence is its own justification’ (p. 14), and writes: ‘An existence which is essentially evolutionary is itself the justification for an evolution towards a more comprehensive existence’ (p. 17). I do not think Dr Waddington is himself at ease in this view, for he does endeavour to recommend the course of evolution to us on three grounds other than its mere occurrence. (a) That the later stages include or ‘comprehend’ the earlier. (b) That T. H. Huxley’s picture of Evolution will not revolt you if you regard it from an ‘actuarial’ point of view. (c) That, any way, after all, it isn’t half so bad as people make out (‘not so morally offensive that we cannot accept it’, p. 18). These three palliatives are more creditable to Dr Waddington’s heart than his head and seem to me to give up the main position. If Evolution is praised (or, at least, apologized for) on the ground of any properties it exhibits, then we are using an external standard and the attempt to make existence its own justification has been abandoned. If that attempt is maintained, why does Dr Waddington concentrate on Evolution: i.e., on a temporary phase of organic existence in one planet? This is ‘geocentric’. If Good = ‘whatever Nature happens to be doing’, then surely we should notice what Nature is doing as a whole; and nature as a whole, I understand, is working steadily and irreversibly towards the final extinction of all life in every part of the universe, so that Dr Waddington’s ethics, stripped of their unaccountable bias towards such a parochial affair as tellurian biology, would leave murder and suicide our only duties. Even this, I confess, seems to me a lesser objection than the discrepancy between Dr Waddington’s first principle and the value judgements men actually make. To value anything simply because it occurs is in fact to worship success, like Quislings or men of Vichy. Other philosophies more wicked have been devised: none more vulgar. I am far from suggesting that Dr Waddington practises in real life such grovelling prostration before the fait accompli. Let us hope that Rasselas, cap. 22, gives the right picture of what his philosophy amounts to in action. (‘The philosopher rose up and departed with the air of a man that had co-operated with the present system.’)