Our whole vocabulary of praise and blame, admiration and contempt, approval and disapproval would have to be eradicated. If someone murdered his neighbor, or exterminated an entire population, we would have no warrant to punish or even criticize that person because, after all, he was simply acting in the manner of a computer program malfunctioning or a stone involuntarily rolling down a hill.

But Kant says that this way of thinking is not only unacceptable, but is also impossible for human beings. People who operate outside the sphere of morality we call psychopaths, and rather than assign them to teach philosophy we put them in straightjackets. We are, by our nature, moral. And it follows from this that we are free, at least to a certain degree, to choose between alternative courses of action because this is the only way we can think and act morally.