Kant regards the universalizability test for maxims as focused on a very special sort of situation: one where the agent is tempted to make an exception to a recognized duty out of self-preference. The universalizability test is supposed help the agent to see, in a particular case of moral judgment, that self-preference is not a satisfactory reason for exempting yourself from a duty you recognize. Kant thinks, as a matter of human nature, that this situation arises often enough and that we need a canon of judgment to guard against it.

The species of anti-Enlightenment religion we find among evangelical protestants is far more impoverished, anti-intellectual and downright wretched.

Our decisions need not be seen as resting on procedures that are merely instrumental in making judgments that are reliably truth-tracking. The procedures might be more directly related than that to truths about what is right or good, or about what we ought to do, or to principles that tell us what is true about these matters. And I have no metaphysical theory about the truth-conditions of such truths, except to say that as objective truths, they must be independent of the attitudes, decisions or actions that they are supposed to justify or for which they are to offer reasons.

It is both theoretically mistaken and morally wrong to regard others as objects of investigation rather than partners in free rational communication.

I think the term "Kantian constructivism" as an oxymoron. Kant was a constructivist about mathematics, but not about ethics.

The Russian revolution did not occur until a generation after Marx's death. He was not involved with it, or with what came after it. His works do not describe post-capitalist society, and a fortiori they do not recommend any part of what the Soviet Union did.

My own view is that Kant's conception of the duality of the good (morality and happiness, the good of our person and the good of our state or condition) is a distinctively modern view.