Why do we accept that paradoxical image of a central Self inside the self? Because it serves us well in many spheres of practical life. Here are some reasons to regard a person as a single thing.
The Physical World: Our bodies act like other objects that take up space. Because of that, we must base our plans and decisions on having a single body. Two people cannot fit where there is room for only one — nor can a person walk through walls or stay aloft without support.
Personal Privacy: When Mary tells Jack something, she must remember to whom it was told, and she must not assume that every other person knows it, too. Also, without the concept of an individual, we could have no sense of responsibility. Mental Activity: We often find it hard to think two different thoughts at once particularly when they're similar, because we get confused when the same agencies are asked to do different jobs at the same time.
Why do our mental processes so often seem to us to flow in streams of consciousness? Perhaps because, in order to keep control, we have to simplify how we represent what's happening. Then, when that complicated mental scene is straightened out, it seems as though a single pipeline of ideas were flowing through the mind.
These are all compelling reasons why it helps to see ourselves as singletons. Still, each of us must also learn not only that different people have their own identities, but that the same person can entertain different beliefs, plans, and dispositions at the same time.
For finding good ideas about psychology, the single-agent image has become a grave impediment. To comprehend the human mind is surely one of the hardest tasks any mind can face. The legend of the single Self can only divert us from the target of that inquiry.