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WHAT is it like to be a bat? Philosopher Thomas Nagel鈥檚 1974 question has evolved to dominate our thinking on consciousness. Nagel鈥檚 point, simply put, is that even if we could fly, and navigate using sonar, we would never grasp what it feels like to be a bat. The argument has become the 鈥渉ard problem鈥� of consciousness, the intractability of explaining subjective experience. Consciousness isn鈥檛 something you can measure or weigh; its ethereal quality is so fascinating as to verge on the mystical. Certainly it attracts plenty of mystical explanations.
So it is unsurprising that, despite decades of thought, we have been unable to explain how our brains create the conscious experience. Even if we might insist that the hard problem is illusory, or that consciousness is simply the way information feels when processed in certain ways, we still need to understand how the illusion arises, and what kind of information in the brain gives rise to the feeling. Philosophy alone isn鈥檛 enough.
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This is where engineering comes in. To build something, you have to understand it precisely. Can we make a machine that does what a conscious being does, that constructs a self-image and uses it to produce descriptions of the world? This week, we report on just such a project (see 鈥�The true nature of consciousness: Solving the biggest mystery of your mind鈥�).
The idea is that, just as any control device needs a model of the thing it is controlling, a brain needs a model of itself. The experience of a phantom limb 鈥� the feeling that an amputated arm, for example, is still present 鈥� comes about because the brain originally created an internal model of the arm to help control its movement. When the physical arm is gone, the model, the phantom, remains. The feeling of consciousness could be the phantom of the brain鈥檚 model of its own workings.
Although an engineering approach won鈥檛 allow us to grasp the essence of 鈥渂atness鈥�, it looks like a promising way to build artificial consciousness. Who knows, it might eventually explain the mystery of our own being.
