Here is the problem. Neurons and yeast cells don’t merely have “different tasks to perform.” They perform differently because they are chemically different.
One water molecule isn’t wet; two aren’t; three aren’t; 100 aren’t; but at some point we cross a threshold, something happens, and the result is a drop of water. But this trick only works because of the chemistry and physics of water molecules! It won’t work with just any kind of molecule. Nor can you take just any kind of molecule, give it the right “tasks to perform,” and make it a fit raw material for producing water.
The fact is that the conscious mind emerges when we’ve collected many neurons together, not many doughnuts or low-level computer instructions. Why should the trick work when I substitute simple computer instructions for neurons? Of course, it might work. But there isn’t any reason to believe it would.
My fellow anticognitivist John Searle made essentially this argument in a paper that referred to the “causal properties” of the brain. His opponents mocked it as reactionary stuff. They asserted that since Searle is unable to say just how these “causal properties” work, his argument is null and void. Which is nonsense again. I don’t need to know anything at all about water molecules to realize that large groups of them yield water, whereas large groups of krypton atoms don’t.
Why the Cognitive Spectrum Is More Exciting than Consciousness
To say that building a useful conscious mind is highly unlikely is not to say that AI has nothing worth doing. Consciousness has been a “mystery” (as Turing called it) for thousands of years, but the mind holds other mysteries, too. Creativity is one of the most important; it’s a brick wall that psychology and philosophy have been banging their heads against for a long time. Why should two people who seem roughly equal in competence and intelligence differ dramatically in creativity? It’s widely agreed that discovering new analogies is the root (or one root) of creativity. But how are new analogies discovered? We don’t know. In his 1983 classic The Modularity of Mind, Jerry Fodor wrote, “It is striking that, while everybody thinks analogical reasoning is an important ingredient in all sorts of cognitive achievements that we prize, nobody knows anything about how it works.”
Furthermore, to speak of the mystery of consciousness makes consciousness sound like an all-or-nothing proposition. But how do we explain the different kinds of consciousness we experience? “Ordinary” consciousness is different from your “drifting” state when you are about to fall asleep and you register external events only vaguely. Both are different from hallucination as induced by drugs, mental illness–or life. We hallucinate every day, when we fall asleep and dream.
And how do we explain the difference between a child’s consciousness and an adult’s? Or the differences between child-style and adult-style thinking? Dream thought is different from drifting or free-associating pre-sleep thought, which is different from “ordinary” thought. We know that children tend to think more concretely than adults. Studies have also suggested that children are better at inventing metaphors. And the keenest of all observers of human thought, the English Romantic poets, suggest that dreaming and waking consciousness are less sharply distinguished for children than for adults. Of his childhood, Wordsworth writes (in one of the most famous short poems in English), “There was a time when meadow, grove, and stream, / The earth, and every common sight, / To me did seem / Apparelled in celestial light, / The glory and the freshness of a dream.”