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.

One rational standard of action is how well it promotes the end it seeks. Another standard is whether it aims at ends which are good. Both of these, but especially the former, depend on judgments of fact.

As with many metaphysical and religious questions, Kant thinks they lie beyond our power to answer them. If you can't stand the frustration involved in accepting this, and insist on finding some more stable position which affords you peace of mind and intellectual self-complacency, then you will find Kant's position "problematic" in the sense that you can't bring yourself to accept it. You may try to kid yourself into accepting either some naturalistic deflationary answer to the problem or some dishonest supernaturalist answer.

Since we cannot know too much about the long term effects of our particular lives, and since success and fame are not good measures of the value of what we have done, it should be enough for any of us that as far as we can tell, in some small way we have made humanity's future better rather than worse.

Kant can provide, and has provided, a good model for philosophers to think about the relation of metaphysics to science and scientific methodology.

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.

What is central to morality is rational self-constraint (acting from duty), in cease where there is no other incentive to do your duty except that the moral law commands it.