It was an important part of Mendelssohn's philosophical and religious view that the traditional rationalist proofs for God's existence should be sound an convincing. Kant thought they were not. So Kant's critique was world-shaking for Mendelssohn.

No theory about our bodies as mere objects of observation and calculation (as distinct from partners in communicative interaction, assumed to be free) can comprehend human nature.

As long as the Republican party exists in its present form, our nation cannot endure as a free society. Still worse, under their policies the human race is being rapidly propelled toward its extinction.

Kant does not think there is anything wrong with being beneficent from sympathy. He thinks we have a duty to cultivate sympathetic feelings by participating in the situations of others and acquiring an understanding of them. He thinks we also have a duty to make ourselves into the kind of person for whom the recognition that something is our duty would be a sufficient incentive to do it (if no other incentives were available to us). That's what he means by "the duty to act from the motive of duty".

Smith could not be expected to have anticipated the horrors that were to come. But even in his own time, he was a defender of certain state actions that he thought necessary in order to safeguard the good effects of commercial society (Smith did not speak of 'capitalism' and was acquainted only with an early undeveloped form of it). Among these state actions the chief was general public education.

I think it is clear that what we ought to do has to be independent of our decisions about what to do, and independent of any procedures we might use in making such decisions.

Teaching and writing about philosophy is about the only thing I've ever been really good at.