Typically great piece by Dr. D. in City Journal. Sample aperçu:
The two greatest moral catastrophes of the twentieth century, wrought by Lenin and Hitler, were perverse effects of the Enlightenment. Lenin and Hitler were creatures of the Enlightenment not in the sense that they were enlightened, of course, but in the sense that they believed they had the right and the duty to act in accordance with their own unaided deductions from their own first principles. Everything else they regarded as sentimentality. Lenin preached no mercy to the non-proletarian, Hitler none to the Jew. The truth of their theories, supposedly rational and indubitable, was more evident to them, more real in their minds, than the millions killed as a consequence of those theories. If a syllogism ended in a command to commit unspeakable evil, you did not doubt the premises or the argument but obeyed the command.