A very famous philosopher named Immanuel Kant flipped traditional ethics

on its head when he suggested that the commitment to moral goodness is only

truly noble and “pure” when it is fully detached from any reward, from any

happiness, from any other purpose whatsoever. 

Kant was worried about the problem of ulterior motives that, he thought,

could water down the noble purpose of the truly good choice.  His separation of goodness from human

happiness has led to what is now the most widespread ethical theory in the

West, namely the opposition of egoism vs. altruism.  Egoism is thought to be acting for the ego,

the self, the “I,” while altruism is thought to be acting for the other.  Kant’s philosophy pits these two motivations

for action against one another fundamentally, so that on Kant’s account, one

could not act both for the other and for the self.  Hence, any action done for one’s own sake

immediately becomes morally problematic, becomes selfish, because it seems to

deprive the other of your duty.