Karl Marx left it to others to find the way beyond capitalism to a higher form of society. He saw his role as giving them as accurate a theory as he could of how capitalism works, which would also show them the reasons why it needs to be abolished and replaced by a freer and more human form of society.

We usually can't know how, and we probably should not even ask, how our lives contribute to a better world.

It is both theoretically mistaken and morally wrong to regard others as objects of investigation rather than partners in free rational communication.

It is actually a nice question how far Descartes himself endorses the monological and metaphysically dualistic theory of mind associated with his name and his legacy in early modern philosophy. But Fichte does reject this tradition, by suggesting that an immaterial thinking substance is an incoherent notion, and a rational being whose rationality was not developed through communication with others is a transcendental impossibility.

Kant considers belief in God and immortality to be items of "faith" because he relates faith to the pursuit of ends - in this case, the highest good.

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

I don't think Kant's theory looks bad to people except insofar as they have misunderstood it (for instance, as heartless and ironheaded, or as committed to an absurd metaphysical conception of freedom that violates Kant's own philosophy).