First, consider Kant's interpretation of what he believes to be the ultimate and universal moral law, which is actually a moral command: The Categorical Imperative. This is his attempt to provide a rational foundation for moral knowledge and an answer to those who believe in ethical relativism. He provides several versions of this law, one being: Act only in accordance with that (subjective) maxim through which you can at the same time will that it become a universal law. Another formulation is: Never treat others as means to an end, but always as ends in themselves (this relates to Kant's conception of an ideal moral community he calls the "Kingdom of Ends").

Our textbook author, Robert Paul Wolff, claims that Kant "liked to say that his Categorical Imperative was nothing more than a philosophically more precise statement of the old Golden Rule: Do unto others as your would have others do unto you....Kant thought [the Categorical Imperative] contained the same basic notion" (pp. 154-155, About Philosophy).

However, there is reason to deny what Wolff says here. Here is what Kant actually says in a footnote in his Groundwork of the Metaphysics of Morals: "Don’t think that the banal ‘Don’t do to anyone else what you wouldn’t want done to you’ could serve here as a guide or principle. It is only a consequence of the real principle, and a restricted and limited consequence at that. It can’t as it stands be a universal law, because it doesn’t provide a basis for duties to oneself, or benevolent duties to others (for many a man would gladly consent to not receiving benefits from others if that would let him off from showing benevolence to them!), or duties to mete out just punishments to others (for the criminal would argue on this ground against the judge who sentences him). And so on."

So it seems that Kant did NOT think that the Categorical Imperative was simply another version of the Golden Rule. Explain why Kant rejects the idea that not doing to anyone else what you don't want done to you falls far short of being a universal moral guide or principle. Why, according to Kant, should a rational moral agent prefer the Categorical Imperative to the Golden Rule?