Psychological egoism is the theory that all our actions are basically motivated by self-interest. It is a view endorsed by several philosophers, among them Thomas Hobbes and Friedrich Nietzsche, and has played a role in some game theory. A self-interested action is one that is motivated by a concern for one’s own interests. Clearly, most of our actions are of this sort. I get a drink of water because I have an interest in quenching my thirst. I show up for work because I have an interest in being paid. But are all our actions self-interested? On the face of it, there seem to be lots of actions that are not. For instance: A motorist who stops to help someone who has broken down. A soldier falling on a grenade to protect others from the explosion. But psychological egoists think they can explain such actions without abandoning their theory. The motorist might be thinking that one day she, too, could need help. So she supports a culture in which we help those in need. The person giving to charity might be hoping to impress others, or they might be trying to avoid feelings of guilt, or they might be looking for that warm fuzzy feeling one gets after doing a good deed. The soldier falling on the grenade might be hoping for glory, even if only the posthumous kind. The first and most obvious objection to psychological egoism is that there are lots of clear examples of people behaving altruistically or selflessly, putting the interests of others before their own. The examples just given illustrate this idea. But as already noted, the psychological egoists think they can explain actions of this kind. But can they? Critics argue that their theory rests on a false account of human motivation. Take , for instance, the suggestion that people who give to charity, or who donate blood, or who help people in need, are motivated by either a desire to avoid feeling guilty or by a desire to enjoy feeling saintly. This may be true in some cases, but surely it simply isn’t true in many. The fact that I don’t feel guilty or do feel virtuous after performing a certain action may be true. But this is often just a side effect of my action. I didn’t necessarily do it in order to get these feelings. Psychological egoists suggest that we are all, at bottom, quite selfish. Even people who we describe as unselfish are really doing what they do for their own benefit. Those who take unselfish actions at face value, they say, are naïve or superficial. Against this, though, the critic can argue that the distinction we all make between selfish and unselfish actions (and people) is an important one. A selfish action is one that sacrifices someone else’s interests to my own: e.g. I greedily grab the last slice of cake. An unselfish action is one where I place another person’s interests above my own: e.g. I offer them the last piece of cake, even though I’d like it myself. Perhaps it is true that I do this because I have a desire to help or please others. In that sense, I could be described, in some sense, as satisfying my desires even when I act unselfishly. But this is exactly what an unselfish person is: namely, someone who cares about others, who wants to help them. The fact that I am satisfying a desire to help others is no reason to deny that I am acting selflessly. On the contrary. That’s exactly the sort of desire that unselfish people have. It satisfies our preference for simplicity. In science we like theories that explain diverse phenomena by showing them to all be controlled by the same force. E.g. Newton’s theory of gravity offers a single principle that explains a falling apple, the orbits of the planets, and the tides. Psychological egoism promises to explain every kind of action by relating them all to one fundamental motive: self-interest it offers a hard-headed, seemingly cynical view of human nature. This appeals to our concern not to be naïve or taken in by appearances. To its critics, though, the theory is too simple. And being hard-headed is not a virtue if it means ignoring contrary evidence. Consider, for instance how you feel if you watch a film in which a two year old girl starts stumbling toward the edge of a cliff. If you’re a normal person, you’ll feel anxious. But why? The film is only a film; it isn’t real. And the toddler is a stranger. Why should you care what happens to her? It isn’t you that is in danger. Yet you do feel anxious. Why? A plausible explanation of this feeling is that most of us have a natural concern for others, perhaps because we are, by nature, social beings. This is a line of criticism advanced by David Hume.