Descartes recommended that we distrust the senses and rely on the ... use of our intellect.

Kant does not think that along with choice of an action we also choose in each case the motive from which we do it. He thinks all is well if I act beneficently, realizing that it is my duty but also having sympathetic feelings for the person I help. But I ought to strive to be the sort of person who would still help even if these feelings were absent. And it is such a case that he presents when the sympathetic friend of humanity finds his sympathetic feelings overclouded by his own sorrows, and still acts beneficently from duty.

Kant's aim was to develop a religion within the boundaries of mere reason (that is, reason unaided by special empirical revelation) and then to ask about existing ecclesiastical faith (especially about Christianity, and the Lutheran Christianity of his time and place) how this revealed faith must be interpreted if it is to be reconciled with reason, and even seen as a wider (though morally optional) extension of a religion of reason.

As I understand it, Kantian constructivism is partly a position in normative ethics and partly a position in metaethics. In metaethics, it is the position that ethical claims have truth values, but their truth conditions consist not in a set of objective facts to which they correspond, but instead in the outcome of some procedure of deliberation resulting in decisions about what to do.

We can't coherently deny, or even decline to affirm, that we are free.

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.

If being "iron headed" is to be lacking such feelings, then Kant's position is that an ironheaded person could not be a moral agent because such a person would not be rational.