The 'Explanatory Gap' was a term coined by Levine in the '80s. It refers to the seeming inability of physical concepts to account for subjectivity. I have commented on a number of books by folks who seem not to understand this gap or at least seem not to fully appreciate it. This expression situates the old mind/body and other minds problem in a more modern philosophical idiom( sorry this sounds so pretentious, but philosophy does that sometimes. Interesting, the basic problems are in some sense always the same but re-expressed.). Basically, the concepts and inference rules of the natural sciences are not sufficient currently to account for subjectivity. The view that experience is somehow the result of purely physical processes is called 'physicalism'. While I ultimately have a strong feeling that all mental phenomena are dependent upon physical phenomena, this has not been proven philosophically. The evidences of the neurosciences provide, to me, anyway, overwhelming evidence of the mental on the physical, but the philosophical issue still remains.
How can it be that science shows, I think definitively, the dependen of the mental life on brain structures and yet there is a remaining philosophical problem? Well, is there a difference between a scientific success and a philosophical one in this context? Well, if neurologists can identify all the parts of the brain and their activities and how they are correlated with mental states, then that is a complete scientific success. One way to state the philosophical problem is, how can the conceptual schemes of the modern natural sciences be used to arrive at our subjectivity, say, for example, our experience of 'green' as we experience? How does one get from the exchange of neurotransmitters etc.. to the color green as we experience it? There seems to be a conceptual gap. We seem to be in need of hybrid concepts to move from these physical concepts to subjective phenomena.
There are a number of issues that also arise in epistemology and evolution:
1. If the mental is completely the result of the physical, and, as mental, has no causal powers over the physical, why should mental states have come about in the first place?
2. Even more, if the mental has no causal powers, then it is cut-off from evolutionary feedback, since its contents are irrelevant. Without this adaptive pressure, why should mental life be considered a reliable picture of the world we inhabit? Why shouldn't we just be hallucinating crazy things while our bodies always behave in an adaptive way if the mental has no effect on the physical? And finally, if our natural sciences are the result of 'observation'(subjective experience), and if there is no reason to trust subjective experience, then why should we trust the conceptual models of the natural sciences that give rise to evolution in the first place?? There's a terrible circularity here.
3. If mental life is causally powerful, what kind of causality is this? It must be 'mental causation', whatever that means, and that sounds spooky, and nonscientific. I understand scientists' reluctance to consider such ideas.
We can hope that somehow in the future this problem can be solved, but it won't be solved I think by science continuing to operate with only current conceptual tools. How to add new tools without becoming weirdly metaphysical? I don't know.
The explanatory gap still allows those who are so inclined to involve ideas like Chardin's and others into their theories. I will talk about this next time.