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.

Kantian ethical theory distinguishes three levels: First, that of a fundamental principle (the categorical imperative, formulated in three main ways in Kant's Groundwork); second, a set of duties, not deduced from but derived from this principle, by way of its interpretation or specification, its application to the general conditions of human life - which Kant does in the Doctrine of virtue, the second main part of the Metaphysics of Morals; and then finally an act of judgment, through which these duties are applied to particular cases.

Fichte thinks that the mutual recognition of one another as free beings belongs among the transcendental conditions of self-consciousness itself.

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 does represents a distinctively modern view of the human condition in contrast to that of ancient high culture, found in ancient Greek ethics and also in ancient Chinese ethics.

There is a lot in Adam Smith that reflects the insights of Rousseau and anticipates those of Marx.

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.