When Marxist biologist J.B.S. Haldane in his article "Auld Hornie, F.R.S." questioned Lewis for being anti-science and against a "planned world" in his "Space Trilogy" ("Mr. Lewis's idea is clear enough. The application of science to human affairs can only lead to hell."), Lewis wrote the following in "A Reply to Professor Haldane":

It certainly is an attack, if not on scientists, yet on something which might be called "scientism" -- a certain outlook on the world which is casually connected with the popularization of the sciences, though it is much less common among real scientists than among their readers. It is, in a word, the belief that the supreme moral end is the perpetuation of our own species, and that this is to be pursued even if, in the process of being fitted for survival, our species has to be stripped of all those things for which we value it -- of pity, of happiness, and of freedom. . . . Under modern conditions any effective invitation to Hell will certainly appear in the guise of scientific planning -- as Hitler's regime in fact did. Every tyrant must begin by claiming to have what his victims respect and to give what they want. The majority in most countries respect science and want to be planned. And, therefore, almost by definition, if any man or group wishes to enslave us it will of course describe itself as "scientific planned democracy". All the more reason to look very carefully at anything which bears that label.

My fears of such a tyranny will seem to the Professor either insincere or pusillanimous. For him the danger is all in the opposite direction, in the chaotic selfishness of individualism. I must try to explain why I fear more the disciplined cruelty of some ideological oligarchy. The Professor has his own explanation of this; he thinks I am unconsciously motivated by the fact that I "stand to lose by social change". And indeed it would be hard for me to welcome a change which might well consign me to a concentration camp (On Stories and Other Essays on Literature, 71-72, 74-75).

Power Corrupts

As the form of government most consistent with his study of natural law and the nature of man, Lewis settled on democracy (not majoritarianism, but self-government as in Alexis de Tocqueville's Democracy in America), considering it the least bad political structure. It should be established only in order to limit centralized political power, however: "I am a democrat because I believe in the Fall of Man" -- or more precisely that man is free to choose good or evil. He realized, though, that

most people are democrats for the opposite reason. A great deal of democratic enthusiasm descends from the ideas of people like Rousseau, who believed in democracy because they thought mankind so wise and good that everyone deserved a share in the government. The danger of defending democracy on those grounds is that they're not true. And whenever their weakness is exposed, the people who prefer tyranny make capital out of the exposure. I find that they're not true without looking further than myself. I don't deserve a share in governing a hen-roost, much less a nation. Nor do most people -- all the people who believe advertisement, and think in catchwords and spread rumours. The real reason for democracy is just the reverse. Man is so fallen that no man can be trusted with unchecked power over his fellows. Aristotle said that some people were only fit to be slaves. I do not contradict him. But I reject slavery because I see no men fit to be masters (Present Concerns, p. 17).