CHAPTER 1
PROLOGUE
Everything should be made as simple as possible, but not simpler.
Albert Einstein
This book tries to explain how minds work. How can intelligence emerge from nonintelligence? To answer that, we''ll show that you can build a mind from many little parts, each mindless by itself.
I''ll call "Society of Mind" this scheme in which each mind is made of many smaller processes. These we''ll call agents. Each mental agent by itself can only do some simple thing that needs no mind or thought at all. Yet when we join these agents in societies -- in certain very special ways -- this leads to true intelligence.
There''s nothing very technical in this book. It, too, is a society -- of many small ideas. Each by itself is only common sense, yet when we join enough of them we can explain the strangest mysteries of mind.
One trouble is that these ideas have lots of cross-connections. My explanations rarely go in neat, straight lines from start to end. I wish I could have lined them up so that you could climb straight to the top, by mental stair-steps, one by one. Instead they''re tied in tangled webs.
Perhaps the fault is actually mine, for failing to find a tidy base of neatly ordered principles. But I''m inclined to lay the blame upon the nature of the mind: much of its power seems to stem from just the messy ways its agents cross-connect. If so, that complication can''t be helped; it''s only what we must expect from evolution''s countless tricks.
What can we do when things are hard to describe? We start by sketching out the roughest shapes to serve as scaffolds for the rest; it doesn''t matter very much if some of those forms turn out partially wrong. Next, draw details to give these skeletons more lifelike flesh. Last, in the final filling-in, discard whichever first ideas no longer fit.
That''s what we do in real life, with puzzles that seem very hard. It''s much the same for shattered pots as for the cogs of great machines. Until you''ve seen some of the rest, you can''t make sense of any part.
1.1 THE AGENTS OF THE MIND
Good theories of the mind must span at least three different scales of time: slow, for the billion years in which our brains have evolved; fast, for the fleeting weeks and months of infancy and childhood; and in between, the centuries of growth of our ideas through history.
To explain the mind, we have to show how minds are built from mindless stuff, from parts that are much smaller and simpler than anything we''d consider smart. Unless we can explain the mind in terms of things that have no thoughts or feelings of their own, we''ll only have gone around in a circle. But what could those simpler particles be -- the "agents" that compose our minds? This is the subject of our book, and knowing this, let''s see our task. There are many questions to answer.
Function: How do agents work?
Embodiment: What are they made of?
Interaction: How do they communicate?
Origins: Where do the first agents come from?
Heredity: Are we all born with the same agents?
Learning: How do we make new agents and change old ones?
Character: What are the most important kinds of agents?
Authority: What happens when agents disagree?
Intention: How could such networks want or wish?
Competence: How can groups of agents do what separate agents cannot do?
Selfness: What gives them unity or personality?
Meaning: How could they understand anything?
Sensibility: How could they have feelings and emotions?
Awareness: How could they be conscious or self-aware?
How could a theory of the mind explain so many things, when every separate question seems too hard to answer by itself? These questions all seem difficult, indeed, when we sever each one''s connections to the other ones. But once we see the mind as a society of agents, each answer will illuminate the rest.
1.2 THE MIND AND THE BRAIN
It was never supposed [the poet Imlac said] that cogitation is inherent in matter, or that every particle is a thinking being. Yet if any part of matter be devoid of thought, what part can we suppose to think? Matter can differ from matter only in form, bulk, density, motion and direction of motion: to which of these, however varied or combined, can consciousness be annexed? To be round or square, to be solid or fluid, to be great or little, to be moved slowly, or swiftly one way or another, are modes of material existence, all equally alien from the nature of cogitation. If matter be once without thought, it can only be made to think by some new modification, but all the modifications which it can admit are equally unconnected with cogitative powers.
Samuel Johnson
How could solid-seeming brains support such ghostly things as thoughts? This question troubled many thinkers of the past. The world of thoughts and the world of things appeared to be too far apart to interact in any way. So long as thoughts seemed so utterly different from everything else, there seemed to be no place to start.
A few centuries ago it seemed equally impossible to explain Life, because living things appeared to be so different from anything else. Plants seemed to grow from nothing. Animals could move and learn. Both could reproduce themselves -- while nothing else could do such things. But then that awesome gap began to close. Every living thing was found to be composed of smaller cells, and cells turned out to be composed of complex but comprehensible chemicals. Soon it was found that plants did not create any substance at all but simply extracted most of their material from gases in the air. Mysteriously pulsing hearts turned out to be no more than mechanical pumps, composed of networks of muscle cells. But it was not until the present century that John yon Neumann showed theoretically how cell-machines could reproduce while, almost independently, James Watson and Francis Crick discovered how each cell actually makes copies of its own hereditary code. No longer does an educated person have to seek any special, vital force to animate each living thing.
Similarly, a century ago, we had essentially no way to start to explain how thinking works. Then psychologists like Sigmund Freud and Jean Piaget produced their theories about child development. Somewhat later, on the mechanical side, mathematicians like Kurt Gödel and Alan Turing began to reveal the hitherto unknown range of what machines could be made to do. These two streams of thought began to merge only in the 1940s, when Warren McCulloch and Walter Pitts began to show how machines might be made to see, reason, and remember. Research in the modern science of Artificial Intelligence started only in the 1950s, stimulated by the invention of modern computers. This inspired a flood of new ideas about how machines could do what only minds had done previously.
Most people still believe that no machine could ever be conscious, or feel ambition, jealousy, humor, or have any other mental life-experience. To be sure, we are still far from being able to create machines that do all the things people do. But this only means that we need better theories about how thinking works. This book will show how the tiny machines that we''ll call "agents of the mind" could be the long sought "particles" that those theories need.
1.3 THE SOCIETY OF MIND
You know that everything you think and do is thought and done by you. But what''s a "you"? What kinds of smaller entities cooperate inside your mind to do your work? To start to see how minds are like societies, try this: pick up a cup of tea!
Your GRASPING agents want to keep hold of the cup.
Your BALANCING agents want to keep the tea from spilling out.
Your THIRST agents want you to drink the tea.
Your MOVING agents want to get the cup to your lips.
Yet none of these consume your mind as you roam about the room talking to your friends. You scarcely think at all about Balance; Balance has no concern with Grasp; Grasp has no interest in Thirst; and Thirst is not involved with your social problems. Why not? Because they can depend on one another. If each does its own little job, the really big job will get done by all of them together: drinking tea.
How many processes are going on, to keep that teacup level in your grasp? There must be at least a hundred of them, just to shape your wrist and palm and hand. Another thousand muscle systems must work to manage all the moving bones and joints that make your body walk around. And to keep everything in balance, each of those processes has to communicate with some of the others. What if you stumble and start to fall? Then many other processes quickly try to get things straight. Some of them are concerned with how you lean and where you place your feet. Others are occupied with what to do about the tea: you wouldn''t want to burn your own hand, but neither would you want to scald someone else. You need ways to make quick decisions.
All this happens while you talk, and none of it appears to need much thought. But when you come to think of it, neither does your talk itself. What kinds of agents choose your words so that you can express the things you mean? How do those words get arranged into phrases and sentences, each connected to the next? What agencies inside your mind keep track of
