How could anything as complex as a human mind work so well for so many years? We all appreciate those splendid feats of writing plays and symphonies. But we rarely recognize how wonderful it is that a person can traverse an entire lifetime without making a single really serious mistake — like putting a fork in one's eye or using a window instead of a door. How do we do such amazing feats as to imagine things we've never seen before, to overcome obstacles, to repair things that are broken, to speak to one another, to have new ideas? What magical trick makes us intelligent? The trick is that there is no trick. The power of intelligence stems from our vast diversity, not from any single, perfect principle. Our species has evolved many effective although imperfect methods, and each of us individually develops more on our own. Eventually, very few of our actions and decisions come to depend on any single mechanism. Instead, they emerge from conflicts and negotiations among societies of processes that constantly challenge one another. In this book we've seen many such dimensions of diversity:
The accumulation of myriad subagents. We learn many different ways to achieve each kind of goal. The many realms of ordinary thought. When one viewpoint fails to solve a problem, we can adopt other perspectives. The endowment of several instinctive protominds. We embody different kinds of organizations for achieving many kinds of goals. The hierarchies of administration grown in accord with Papert's principle. When simple methods fail, we can build new levels of organization. The evolutionary vestiges of animals that still remain inside our brains. We use machinery evolved from fish, amphibia, reptiles, and earlier mammals. The sequence of stages of the growing child's personality. We accumulate different personalities that we can apply to
different situations. The complex, ever-growing heritage of language and culture. We can use methods and ideas developed by millions of our ancestors. The subordination of thought processes to censors and suppressors. We do not need perfect methods, since we can remember how imperfect methods fail.
Each of these dimensions gives you toughness and versatility. They offer alternative ways to proceed when any system fails. If part of your society of mind proposes to do what other parts find unacceptable, your agencies can usually find another way. Sometimes you merely need to turn to another branch of the same accumulation. When that fails, you can ascend to a higher level and engage a larger change in strategy. Then, even if an entire agency should fail, your brain retains earlier versions of it. This means that every facet of your personality may have the option to regress to an earlier stage, which already has proved itself competent to deal with the usual problems of life. Finally, when even that won't work, you can usually switch to an entirely different family of agencies. Whenever anything goes wrong, there are always other realms of thought.