 As already intimated, while advocates of altruism and of egoism agree that people often help others, they disagree about why they do this. On the standard account, defenders of altruism insist that, sometimes at least, people are motivated by an ultimate desire for the well-being of another person, while defenders of egoism maintain that all ultimate desires are self-interested. This formulation invites questions about (1) what it is for a behavior to be motivated by an ultimate desire, and (2) the distinction between desires that are self-interested and desires for the well-being of others.