How do we control our minds? Ideally, we first choose what we want to do, then make ourselves do it. But that's harder than it sounds: we spend our lives in search of schemes for self-control. We celebrate when we succeed, and when we fail, we're angry with ourselves for not behaving as we wanted to — and then we try to scold or shame or bribe ourselves to change our ways. But wait! How could a self be angry with itself? Who would be mad at whom? Consider an example from everyday life.
I was trying to concentrate on a certain problem but was getting bored and sleepy. Then I imagined that one of my competitors, Professor Challenger, was about to solve the same problem. An angry wish to frustrate Challenger then kept me working on the problem for a while. The strange thing was, this problem was not of the sort that ever interested Challenger.
What makes us use such roundabout techniques to influence ourselves? Why be so indirect, inventing misrepresentations, fantasies, and outright lies? Why can't we simply tell ourselves to do the things we want to do?
To understand how something works, one has to know its purposes. Once, no one understood the heart. But as soon as it was seen that hearts move blood, a lot of other things made sense: those things that looked like pipes and valves were really pipes and valves indeed — and anxious, pounding, pulsing hearts were recognized as simple pumps. New speculations could then be formed: was this to give our tissues drink or food? Was it to keep our bodies warm or cool? For sending messages from place to place? In fact, all those hypotheses were correct, and when that surge of functional ideas led to the guess that blood can carry air as well, more puzzle parts fell into place.
To understand what we call the Self, we first must see what Selves are for. One function of the Self is to keep us from changing too rapidly. Each person must make some long-range plans in order to balance single-purposeness against attempts to do everything at once. But it is not enough simply to instruct an agency to start to carry out our plans. We also have to find some ways to constrain the changes we might later make — to prevent ourselves from turning those plan-agents off again! If we changed our minds too recklessly, we could never know what we might want next. We'd never get much done because we could never depend on ourselves.
Those ordinary views are wrong that hold that Selves are magic, self-indulgent luxuries that enable our minds to break the bonds of natural cause and law. Instead, those Selves are practical necessities. The myths that say that Selves embody special kinds of liberty are merely masquerades. Part of their function is to hide from us the nature of our self-ideals — the chains we forge to keep ourselves from wrecking all the plans we make.