Behavior in the experimental games described in the last chapter cannot, then, be explained by self-interested desires alone, whether the desires are for the benefits of cooperation in later periods, or to satisfy one's taste for equity, or to avoid social or other external sanctions, or to avoid the alleged internal sanctions of shame or guilt. Nor can much cooperative behavior in the real world – the world outside the experimenters' laboratories – be explained in this way. (We'll see some examples in the next chapter.) This is not to say that sanctions are never required, for example, to deter crime; but, as H. L. A. Hart said, they are not “the normal motive for obedience” to the law, and I have argued that they cannot be the only motive sustaining cooperation.

What then is the normal motive – the motive of normally social human beings – for obeying the norm of fair reciprocity, if it is not self-interest? The short answer is that most people think it is wrong not to obey this norm – they believe they ought to obey it. But what do we mean when we say that an action is wrong, and how can a mere belief or judgment that an act is right motivate us to do it?

For the economists and other Rational Choice theorists (and some philosophers as well), there is no conceptual or internal connection between moral belief and motivation.