 The first point to be made about this form of psychological egoism is that, once again, there is no a priori argument to support it. The two premises we have been examining—that all action is motivated by desire and all desire is like hunger—are implausible, and so they do not support the thesis that we never sacrifice our well-being to any degree. If this form of psychological egoism is to be sustained, its evidence would have to be drawn from the observation of each human being’s reasons for acting. It would have to say: when our motives are carefully scrutinized, it may indeed be found that although we do good to others for the sake of those others, we never do so when we think it would detract even slightly from our own well-being. In other words, we count the good of others as something that by itself gives us a reason, but it is always a weak reason, in that it is never as strong as reasons that derive from our self-interest.