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A brain and body are made the same way. From the bottom up. Instead of towns, you begin with simple behaviors -- instincts and reflexes. You make a little circuit that does a simple job, and you get a lot of them going. Then you overlay a secondary level of complex behavior that can emerge out of that bunch of working reflexes. The original layer keeps working whether the second layer works or not. But when the second layer manages to produce a more complex behavior, it subsumes the action of the layer below it.

Here is the generic recipe for distributed control that Brooks's mobot lab developed. It can be applied to most creations:

1) Do simple things first.

2) Learn to do them flawlessly.

3) Add new layers of activity over the results of the simple tasks.

4) Don't change the simple things.

5) Make the new layer work as flawlessly as the simple.

6) Repeat, ad infinitum.

This script could also be called a recipe for managing complexity of any type, for that is what it is.

What you don't want is to organize the work of a nation by a centralized brain. Can you imagine the string of nightmares you'd stir up if you wanted the sewer pipe in front of your house repaired and you had to call the Federal Sewer Pipe Repair Department in Washington, D.C., to make an appointment?

The most obvious way to do something complex, such as govern 100 million people or walk on two skinny legs, is to come up with a list of all the tasks that need to be done, in the order they are to be done, and then direct their completion from a central command, or brain. The former Soviet Union's economy was wired in this logical but immensely impractical way. Its inherent instability of organization was evident long before it collapsed.

Central-command bodies don't work any better than central-command economies. Yet a centralized command blueprint has been the main approach to making robots, artificial creatures, and artificial intelligences. It is no surprise to Brooks that braincentric folks haven't even been able to raise a creature complex enough to collapse.

Brooks has been trying to breed systems without central brains so that they would have enough complexity worth a collapse. In one paper he called this kind of intelligence without centrality "intelligence without reason," a delicious yet subtle pun. For not only would this type of intelligence -- one constructed layer by layer from the bottom up -- not have the architecture of "reasoning," it would also emerge from the structure for no apparent reason at all.

The USSR didn't collapse because its economy was strangled by a central command model. Rather it collapsed because any central-controlled complexity is unstable and inflexible. Institutions, corporations, factories, organisms, economies, and robots will all fail to thrive if designed around a central command.

Yes, I hear you say, but don't I as a human have a centralized brain?

Humans have a brain, but it is not centralized, nor does the brain have a center. "The idea that the brain has a center is just wrong. Not only that, it is radically wrong," claims Daniel Dennett. Dennett is a Tufts University professor of philosophy who has long advocated a "functional" view of the mind: that the functions of the mind, such as thinking, come from non-thinking parts. The semimind of a insectlike mobot is a good example of both animal and human minds. According to Dennett, there is no place that controls behavior, no place that creates "walking," no place where the soul of being resides. Dennett: "The thing about brains is that when you look in them, you discover that there's nobody home."

Dennett is slowly persuading many psychologists that consciousness is an emergent phenomenon arising from the distributed network of many feeble, unconscious circuits. Dennett told me, "The old model says there is this central place, an inner sanctum, a theater somewhere in the brain where consciousness comes together. That is, everything must feed into a privileged representation in order for the brain to be conscious. When you make a conscious decision, it is done in the summit of the brain. And reflexes are just tunnels through the mountain that avoid the summit of consciousness."

From this logic (very much the orthodox dogma in brain science) it follows, says Dennett, that "when you talk, what you've got in your brain is a language output box. Words are composed by some speech carpenters and put in the box. The speech carpenters get directions from a sub-system called the 'conceptualizer' which gives them a preverbal message. Of course the conceptualizer has to gets its message from some source, so it all goes on to an infinite regress of control."

Dennett calls this view the "Central Meanor." Meaning descends from some central authority in the brain. He describes this perspective applied to language -- making as the "idea that there is this sort of four-star general that tells the troops, 'Okay, here's your task. I want to insult this guy. Make up an English insult on the appropriate topic and deliver it.' That's a hopeless view of how speech happens."

Much more likely, says Dennett, is that "meaning emerges from distributed interaction of lots of little things, no one of which can mean a damn thing." A whole bunch of decentralized modules produce raw and often contradictory parts -- a possible word here, a speculative word there. "But out of the mess, not entirely coordinated, in fact largely competitive, what emerges is a speech act."

We think of speech in literary fashion as a stream of consciousness pouring forth like radio broadcasts from a News Desk in our mind. Dennett says, "There isn't a stream of consciousness. There are multiple drafts of consciousness; lots of different streams, no one of which will be singled out as the stream." In 1874, pioneer psychologist William James wrote, "...the mind is at every stage a theatre of simultaneous possibilities. Consciousness consists in the comparisons of these with each other, the selection of some, and the suppression of the rest...."

The idea of a cacophony of alternative wits combining to form what we think of as a unified intelligence is what Marvin Minsky calls "society of mind." Minsky says simply "You can build a mind from many little parts, each mindless by itself." Imagine, he suggests, a simple brain composed of separate specialists each concerned with some important goal (or instinct) such as securing food, drink, shelter, reproduction, or defense. Singly, each is a moron; but together, organized in many different arrangements in a tangled hierarchy of control, they can create thinking. Minsky emphatically states, "You can't have intelligence without a society of mind. We can only get smart things from stupid things."

The society of mind doesn't sound very much different from a bureaucracy of mind. In fact, without evolutionary and learning pressures, the society of mind in a brain would turn into a bureaucracy. However, as Dennett, Minsky, and Brooks envision it, the dumb agents in a complex organization are always both competing and cooperating for resources and recognition. There is a very lax coordination among the vying parts. Minsky sees intelligence as generated by "a loosely-knitted league of almost separate agencies with almost independent goals." Those agencies that succeed are preserved, and those that don't vanish over time. In that sense, the brain is no monopoly, but a ruthless cutthroat ecology, where competition breeds an emergent cooperation.

The slightly chaotic character of mind goes even deeper, to a degree our egos may find uncomfortable. It is very likely that intelligence, at bottom, is a probabilistic or statistical phenomenon -- on par with the law of averages. The distributed mass of ricocheting impulses which form the foundation of intelligence forbid deterministic results for a given starting point. Instead of repeatable results, outcomes are merely probabilistic. Arriving at a particular thought, then, entails a bit of luck.

Dennett admits to me, "The thing I like about this theory is that when people first hear about it they laugh. But then when they think about it, they conclude maybe it is right! Then the more they think about it, they realize, no, not maybe right, some version of it has to be right!"

As Dennett and others have noted, the odd occurrence of Multiple Personalities Syndrome (MPS) in humans depends at some level on the decentralized, distributed nature of human minds. Each personality -- Billy vs. Sally -- uses the same pool of personality agents, the same community of actors and behavior modules to generate visibly different personas. Humans with MPS present a fragmented facet (one grouping) of their personality as a whole being. Outsiders are never sure who they are talking to. The patient seems to lack an "I."

But isn't this what we all do? At different times of our life, and in different moods, we too shift our character. "You are not the person I used to know," screams the person we hurt by manifesting a different cut on our inner society. The "I" is a gross extrapolation that we use as an identity for ourselves and others. If there wasn't an "I" or "Me" in every person then each would quickly invent one. And that, Minsky says, is exactly what we do. There is no "I" so we each invent one.

There is no "I" for a person, for a beehive, for a corporation, for an animal, for a nation, for any living thing. The "I" of a vivisystem is a ghost, an ephemeral shroud. It is like the transient form of a whirlpool held upright by a million spinning atoms of water. It can be scattered with a fingertip.

But a moment later, the shroud reappears, driven together by the churning of a deep distributed mob. Is the new whirlpool a different form, or the same? Are you different after a near-death experience, or only more mature? If the chapters in this book were arranged in a different order, would it be a different book or the same? When you can't answer that question, then you know you are talking about a distributed system.