We can treat human responses to cognitions as involving law-like connections grounded on free choices which show themselves in our character.

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

We cannot predict the effects of our actions, especially our collective actions over generations or centuries, to use instrumental reasoning toward these big final ends to tell us what we ought to do.

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 says that we may regard ourselves as legislator of the moral law, and consider ourselves as its author, but not that we are legislators or authors of the law.

Clearly no working class movement ever came about that was able to do what Marx was hoping for.

Not only our moral life, but even our use of theoretical reason - on which we rely in rationally inquiring into nature - presupposes that we are free.