If the problem of free will is to see how freedom fits into the order of nature, then Kant's basic view about the free will problem is that it is insoluble.

It would be nice, wouldn't it? if we could get comfortable about the problem of freedom. Kant thinks that we can't.

That Hegel's theory is derivative from Fichte's does not prevent it from being strikingly original and of independent value.

In fact people do not know enough about themselves and what is good for them to form a sufficiently definite conception of the general happiness (or whatever the end is) to establish definite rules for its pursuit.

Kant has been famous for his rejection of eudaimonism, but I think Kantian ethics has a great deal in common with Aristotle, and some things in common with Stoicism as well. The traditions tend, I believe, to talk past each other when it comes to happiness or eudaimonia.

Freedom is an unprovable but unavoidable presupposition, not an article of faith.

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.