...confronted even with Christ turns away to consider the judgement of his own conscience and to hear the voice of his own reason . . . . This man is with us still, free, independent, lonely, powerful, rational, responsible, brave, the hero of so many novels and books of moral philosophy. The raison d’être of this attractive but misleading creature is not far to seek . . . .Lucifer? Satan? Why such a harsh judgment? Perhaps because the modern, "rational" man believes only what science and his senses tell him. The rational man looks at himself and his fellows as little more than flesh and bone machines, animals, whose only real "purpose" is to reproduce, experience pleasure and avoid pain.
He is the ideal citizen of the liberal state, a warning held up to tyrants. He has the virtue which the age requires and admires, courage. It is not such a very long step from Kant to Nietzsche, and from Nietzsche to existentialism and the Anglo-Saxon ethical doctrines which in some ways closely resemble it.
In fact, Kant’s man had already received a glorious incarnation nearly a century earlier in the work of Milton: his proper name is Lucifer.
He regards morality as an illusion. His reason affords him no basis for caring about the weak or the poor, no basis for human compassion, no particular point to conserving the earth's resources for future generations.
Whereas Kant thought that reason dictated the categorical imperative, i.e. the duty to treat others as ends in themselves and not merely as a means to one's own happiness, the fact is that reason, unfettered from any divine sanction, dictates only that each should look to his own interests.
In practice modern man may care about the well-being of others, but he must abandon his fealty to science and reason to do so because these provide no justification for any moral obligations whatsoever.
Indeed, the purely rational man is led by the logic of his naturalism to the conclusion that might makes right. The pursuit of power frequently becomes the driving force of his life. It injects his life with meaning. It leads him to build abattoirs like Auschwitz and Dachau to eliminate the less powerful and less human. It leads him to employ vast prison camps like the Soviet Gulag to dispose of the millions who hold inconvenient political opinions or who otherwise stand in his way.
Would Kant have endorsed the notion that might makes right? No, but then Kant wasn't quite in tune with the modern, rational man. Kant believed that in order to make sense of our lives as moral agents we have to assume that three things are true: We have to assume that God exists, that we have free will, and that there is life beyond the grave.
The modern man, of course, rejects all three, and in so doing he rejects the notion of objective moral value or obligation. That's why reason has led men in the 20th century to embrace ideologies that have produced vast tracts of corpses, and that's why, perhaps, Murdoch uses the name Lucifer to describe them.