When people think that moral problems can be solved by some simple strategy of calculation, that sets them up for ghastly overreaching. They think they can turn everything into a "science" the way mechanics was turned into a science in the seventeeth century. They want to turn everything over to technocrats and social engineers. They become shortsighted or simplistic about their ends, and they disastrously overestimate their ability to acquire the information they need to make the needed calculations.

The moral law is simply the way we think our own freedom as self-determination.

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.

Adam Smith was aware of the way that economic interests could have a distorting and destructive effect both on the market and on politics.

Kant's treatments of rational theology and metaphysics were aimed primarily at theoretical questions. His attitude toward the pseudo-sciences of "special metaphysics" in Wolff and Baumgarten was always double-edged. He did see them as pseudo-sciences but also valued their doctrinal value and especially their regulative value for the empirical sciences. Like his views about religion, I don't think any of this is any longer viable in its original form.

Capitalism has proven to be a far more terrible system than Marx could ever bring himself to imagine. Those who are so deluded as to find something good in it, or even feel loyalty toward it, are its most pitiful victims.

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.