As I mentioned recently, I’ve just read John Searle’s book The Mystery of Consciousness. Searle holds a sort of middle ground among philosophers of mind: he is a card-carrying physicalist, meaning that he rejects the idea that our minds are non-material entities that interact with the body in some ghostly way, but he also takes issue with functionalist philosphers who argue that consciousness is simply an emergent property of sufficiently complex information-processing systems. Searle’s best-known salvo against functionalism is his famous “Chinese Room” thought experiment, which I won’t recap here, but which has been a source of lively dispute ever since it was published in 1980.
Although I am not persuaded by the Chinese Room argument, I do think Searle makes a very sensible case for regarding hard-core functionalism, and its cousin, “strong” Artificial Intelligence, with a doubtful eye. While it may be possible that a computer running an enormously complex program could be a system from which consciousness might emerge, there is little ground for assuming that this is likely, and I think that the example, sometimes given, of gradually replacing a human brain a neuron at a time with artificial components overlooks much about the biological brain that may be of crucial importance.
Yes, the brain is an information-processing system, but it is a particular kind of system, and it is far too early to be able to point to a single feature of the brain and claim that that is what creates consciousness. For all our speculation, the fact remains that the only thing in the world in which we can be sure that consciousness resides is the biological human brain, and to study it with the aim of understanding how it creates consciousness we must consider the interactions of all of its features, which include, just for starters:
- The abstract patterns of neural connection and excitation, and the information contained therein (this is what AI proponents suggest might be sufficient for consciousness when abstracted into other frameworks).
- The physical structure of the cells themselves (this is the area that Penrose and Hameroff are focusing on in their investigation of quantum-mechanical effects in neural-cell microtubules).
- The chemical environment both within and surrounding the neural tissue.
- The varying electromagnetic fields that permeate the conscious brain.
Any of these features, and of course their deeply entwined and recursive interactions, may be crucial to the emergence of consciousness. To disregard the enormous biological intricacy of the brain and focus only on its most abstract feature seems quite unjustifiable, given our nearly complete ignorance of the basic principles of consciousness, and Searle is right to call this to our attention.
Can machines be conscious? Searle asks. Yes, they clearly can, because we are machines, and we are conscious. But in virtue of what, exactly, is the human machine able to accomplish such a thing? That is a question to which we do not yet have even the slightest glimmer of an answer, and it is far too early to pretend that we do. What we need to do right now is simply to continue to examine, from every available angle, the one and only system we know to be conscious. That should be enough to keep us busy for quite some time.