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You came to this book assuming that the basic units of human cognition are states such as thoughts, beliefs, perceptions, desires, and preferences. That assumption is natural enough: it is built into the vocabulary of every natural language. And each state is typically identified by way of a specific sentence in one's natural language: one has the belief that P, or the desire that Q, for example, where P and Q are sentences. Human cognition is thus commonsensically portrayed as a dance of sentential or propositional states, with the basic unit of computation being the inference from several such states to some further sentential state. ¶ These assumptions are central elements in our standard conception of human cognitive activity, a conception often called "folk psychology" to acknowledge it as the common property of folks generally. Their universality notwithstanding, these bedrock assumptions are probably mistaken.

But who, in that case, can be watching this pixilated show? The answer is straightforward: no one. There is no distinct "self" in there, beyond the brain as a whole. On the other hand, almost every part of the brain is being "watched" by some other part of the brain, often by several other parts at once.

The religious hypothesis of mind-body dualism has been in trouble with evolutionary biology, and with several other sciences as well, for more than a century. It didn't need any special input from artificial intelligence or neuroscience to make it scientifically implausible. I bring it up here only because it is a clear example of a popular and important belief currently under siege by modern information. And because its example may be repeated. The fact is, there is a much more intriguing area of current conceptual commitment, one more likely to be affected by emerging cognitive theory in particular. It lies even closer to home and is even more widespread, if that is possible, than mind-body dualism. It is our current self-conception: our shared portrait of ourselves as self-conscious creatures with beliefs, desires, emotions, and the power of reason.

Your brain is far too complex and mercurial for its behavior to be predicted in any but the broadest outlines or for any but the shortest distances in the future. Faced with the extraordinary dynamical features of a functioning brain, no device constructible in this universe could ever predict your behavior, or your thoughts, with anything more than merely statistical success. ¶ So one need not fear being reduced to a clanking robot or an empty machine. Quite to the contrary, we are now in a position to explain how our vivid sensory experience arises in the sensory cortex of our brains: how the smell of baking bread, the sound of an oboe, the taste of a peach, and the color of a sunrise are embodied in a vast chorus of neural activity. We now have the resources to explain how the motor cortex, the cerebellum, and the spinal cord conduct an orchestra of muscles to perform the cheetah's dash, the falcon's strike, or the ballerina's dying swan. ... On this matter of conceptual development there is especial cause for wonder. For the human brain, with a volume of roughly a quart, encompasses a space of conceptual and cognitive possibilities that is larger, by one measure at least, than the entire astronomical universe. It has this striking feature because it exploits the combinatorics of its 100 billion neurons and their 100 trillion synaptic connections with each other.