by Yohan J. John
As a neuroscientist, I am frequently asked about consciousness. In academic discourse, the celebrated problem of consciousness is often divided into two parts: the "Easy Problem" involves identifying the processes in the brain that correlate with particular conscious experiences. The "Hard Problem" involves murkier questions: what are conscious experiences, and why do they exist at all? This neat separation into Easy and Hard problems, which comes courtesy the Australian philosopher David Chalmers, seems to indicate a division of labor. The neuroscientists, neurologists and psychologists can, at least in principle, systematically uncover the neural correlates of consciousness. Most of them agree that calling this the "Easy Problem" somewhat underestimates the theoretical and experimental challenges involved. It may not be the Hard Problem, but at the very least it's A Rather Hard Problem. And many philosophers and scientists think that the Hard Problem may well be a non-problem, or, as Ludwig Wittgenstein might have said, the kind of problem that philosophers typically devise in order to maximize unsolvability.
One might assume that as a neuroscientist, I should be gung-ho to prove the imperious philosophers wrong, and to defend the belief that science can solve any sort of problem one might throw at it: hard, soft, or half-baked. But I have become increasingly convinced that science is severely limited in what it can say about consciousness. In a very important sense, consciousness is invisible to science.
The word "consciousness" means different things to different people, so it might help to cover some of the typical ways its used. The most objective notion of consciousness arises in the world of medicine. We don't usually require a degree in philosophy to tell when a person is conscious and when they are unconscious. The conscious/unconscious distinction is only loosely related to subjective experience: we say a person is unconscious if they are unresponsive to stimuli. These stimuli may come from outside the body, or from the still-mysterious wellspring of dreams.
But the interesting thing about any "medical" definition of consciousness is that it evolves with technology.
