Aristotle and Kant

For Kant, the reason why the Critique of Pure Reason has to do with understanding, and the Critique of Practical Reason with morality, is that for Aristotle, theoretical knowledge is different than practical knowledge. It is one thing to know the virtues as a theoretical matter; another to practice them. Aristotle points to the shared word-root between ethics and ethos, or habit. One becomes virtuous by getting in the habit of practicing the virtues. We might be skeptical of this as the American wisdom of “smile, and you’ll feel better.” We need something to feel good about. We need to be inspired to practice the virtues. This is the Socratic wisdom, in the Meno, that virtue cannot be taught. Admittedly, it is rare that Socrates comes down on one side of this question in the dialogues, which he is always asking. Aristotle holds political science to be about training for virtue, so that all the language today about education as a training for citizenship is directly derived from the Ethics. In contemporary mass democracy, where political activity is reduced to voting rather than office-holding, education might better be said to consist in distinguishing between information and misinformation. Whether this is something that can be taught is also unclear.

This distinction between theory as knowledge and morality as practice, or reason on the one hand and practical reason on the other, is assumed by Kant. Hence his talk of “maxims” in the context of practical reason, in the same way that the Ten Commandments are spoken of, in English, as “precepts.” They are rules for action to be incorporated in practice, rather than merely known as a matter of theory.