Hegel's theory of recognition is basically derived from Fichte, who is its real author.

Kant's system of duties constitutes a Doctrine of Virtue because the duties also indicate what kinds of attitudes, dispositions and feelings are morally virtuous or vicious.

Utilitarians are usually empiricists who think they can solve every problem by accumulating enough empirical facts. They do not realize that thinking as well as experience is necessary to know anything or get anything right.

Both Kant and Fichte thought of traditions of revealed religion as ways of symbolically (that is, with aesthetic emotional power) thinking about our moral condition. Both thought that religion would become more and not less powerful, emotionally and morally, if the claims of scriptures and religious teachings were taken symbolically rather than literally (whatever 'literally' might mean in the case of claims that are either nonsensical or outdated or historically unsupportable if taken as metaphysical or historical assertions).

Kant can provide, and has provided, a good model for philosophers to think about the relation of metaphysics to science and scientific methodology.

Marx's own illusion was to think that the working class movement, which he devoted his life to creating and strengthening, would both be socially and politically successful in the industrial nations of Western Europe, and that it would develop an entirely new way of human social life that would retain and even enhance the productive benefits of capitalism while overcoming the inhumanity and exploitation of capitalist social relations. Marx himself had no solutions to these problems. His object of study was capitalism itself.

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.