Schopenhauer
According to Schopenhauer, Kant is right on two points: (1) Morality is to be separated from self-interest. (2) The categorical imperative states a universal law for all rational agents. But Kant is wrong to believe that his second point supports the first. The only purely rational aspect of morality is a demand for consistency that is compatible with any content whatever. We understand morality only when we see that it rests on compassion for others, which moves us to care about the welfare and suffering of others for their own sake. The right moral outlook requires us to overcome two errors about the reality of other people: (1) Egoism rests on failure to recognize that other people are just as real as I am. (2) Compassion requires us to see that there is no real distinction between myself and other people.