At interdisciplinary conferences and forums about consciousness, I’ve noticed that more than a few scientists seem to seriously misunderstand the Hard Problem of Consciousness (HPC). In fact, I’ve begun to wonder whether misunderstanding the HPC is closer to the norm among scientists interested in consciousness.
Confusion about the HPC becomes evident to me when someone appeals to the wealth of evidence we have for neural correlates of consciousness (NCCs) as if merely being informed of strong NCCs is sufficient for seeing that the HPC has a solution. This suggests to me that the scientist believes that appreciating the alleged solution to the HPC is merely a matter of becoming convinced on the basis of empirical evidence that brains somehow realize conscious states. But the HPC is not a problem of becoming convinced of this; it is a problem that typically presupposes this. Here is David Chalmers doing just that in his 1995 presentation of the HPC, my emphasis in bold.
It is undeniable that some organisms are subjects of experience. But the question of how it is that these systems are subjects of experience is perplexing. Why is it that when our cognitive systems engage in visual and auditory information-processing, we have visual or auditory experience: the quality of deep blue, the sensation of middle C? How can we explain why there is something it is like to entertain a mental image, or to experience an emotion? It is widely agreed that experience arises from a physical basis, but we have no good explanation of why and how it so arises. Why should physical processing give rise to a rich inner life at all? It seems objectively unreasonable that it should, and yet it does.
If any problem qualifies as the problem of consciousness, it is this one.
—David Chalmers, ‘Facing Up to the Problem of Consciousness’
Here, the HPC is presented as a problem for anyone who is already convinced that physical states somehow “give rise to” (a phrase vague enough to include the variety of proposed relations) phenomenally conscious states. Granted, some people may use the HPC as a reason to reject the view that physical states give rise to conscious states. However, rejecting that view—even mere skepticism of it—is not essential to believing there is a HPC. And in fact, many of us are struck by the HPC precisely because we do hold the view that physical states somehow give rise to conscious states. We aren’t asking to be convinced of this relation between body and mind; we are hoping to better understand it. The HPC, then, is at first pass, a challenge to fill or bridge the explanatory gap between the physical and the phenomenally conscious.
But this is not all it is, for Chalmers also alleges that closing the explanatory gap imposes difficulties of a special, essentially more difficult kind. (Thus the H in the HPC.) Most problems, however complex, are not hard in Chalmers’s sense. I may not know exactly how pressing my gas pedal brings about the acceleration of my car, but I know what a complete mechanical explanation would look like. This question of physics has an answer in physics. But not so, Chalmers holds, with the HPC. For those who find the HPC to be truly hard, it is not clear how any degree of physical description could ever reveal why there is something it’s like to be in a particular brain state.