Radical versions of physicalism fail at the level of our intuitions. I don’t mean to suggest by this that our intuitions are the last word on what can be accepted as true or false, but we do rely on our intuitions where neither the force of logic or the evidence of sense supports one account at the expense of all other accounts of complex phenomena.
This is sufficient for most people, even keeping an open mind, to regard the physicalist agenda as excessively optimistic, if not grandiose. That such assessments might be premature, has been suggested by more than one philosopher. Galen Strawson in Mental Reality argues that the real problem with physicalism is that we simply do not know enough about matter itself. He calls himself an agnostic materialist and he puts his position this way:
“According to agnostic materialism, the idea that the mind-body problem is particularly perplexing flows from our unjustified and relatively modern faith that we have an adequate grasp of the fundamental nature of matter, as some crucial general level of understanding, even if we are still uncertain about many details.“
Galen Strawson remains committed to monism, to monistic physicalism, nonetheless. But he must remain neutral, or as he would have it, agnostic, as to just what the physics of it all might in the future turn out to be. I regard this as a modest position to take, one that, at some level, I suspect all conjectures about the nature matter, accept. It adds nothing to the debate, however, except that small clause about how science at this point cannot explain everything.
Although the age of Newton (not to mention achievements in the ancient world) have supplied us with detailed descriptions of the physical world at the macro-level, it is important to keep in mind that at the micro-level, at the level of particles, the science of physics is a fairly young subject. It is not only young, but by historic standards entirely surprising. I’m not sure how physicists prior to 1900 would have reacted to the fact that, for example, the neutral B meson goes from its particle to its anti-particle state at a rate of some three trillion times each second. They never faced such a challenge, in part because the measurement of such events, occurring at such a rate, was simply impossible. And what might they have said about there being six flavors of quarks, not to mention a strange quark, into the bargain.
In all, then, the expectation that physics will provide an increasingly detailed and perhaps evermore surprising account of the material world is sound and sensible. Agnostic materialism I argue is a non-position. While sound and sensible, it is just as problematic as all forms of agnosticism are. Except for the materialism, it is not a position about the ontology of the universe. It is merely an epistemological posture one takes with regard to things one cannot ultimately know all the things there is to know about it.
It would also seem sensible to conclude even at this early date that if consciousness proves to be something finally and ultimately physical, it will surely not be at the macro-level of chunks of brain tissue, but at the level of sub-particles. Accordingly, if the physicalist is to press on with attempts to ground consciousness in physics, there is good reason to believe that quantum physics will ultimately seal the causal closure debate.