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

Some of Kant's particular moral opinions, either because he shared the prejudices of his time, or because of his own personal crotchets, can strike sensible people as ridiculous or offensive. But in my view, his own theory provides us with the resources (the best resources available, I believe) to correct his own personal errors or cultural prejudices.

We commit not only theoretical error but also moral wrong in objectifying ourselves or other rational beings, ignoring their capacities for free action and communicative interaction with us.

We totally misunderstand both his aims and his contribution if we try to read into Marx some anticipation of either the modest successes or the disastrous failures of those who later thought they were acting in his name.

For the utilitarian, there is a fact of the matter about the good (the general happiness, or whatever conception of the good the utilitarian adopts) and about which actions or moral rules would contribute to maximizing the good. For the rational intuitionist, there are truths about which actions should be done and not done.

Notice that tearing oneself out of the insensible state is the opposite of remaining in it; the man who is beneficent from duty nevertheless acts with feelings, if not with empirical inclinations.

Being aware of truths about what is good or right or about what we ought to do is not the same as deciding what to do. Nor can the former truths be derived from decisions about what to do, or about procedures for making such decisions, unless these procedures themselves rest in some way on the apprehension of truths about what we ought to do.