First Egnor gives us a tutorial on the eloquent and non-eloquent areas of the brain and gives us the following diagram:
[The] non-eloquent areas (where brain anatomy does not correlate with specific function) are in tan, and the eloquent areas (where brain anatomy does correlate with specific function) are the named colored areas. As you can see, most of the brain mass is non-eloquent and does not anatomically correlate with specific brain function in any precise way. In fact, one can surgically remove much of the non-eloquent brain without significant discrete neurological deficit. Major portions of the frontal lobes, temporal lobes, parietal lobes, occipital lobes, and cerebellar hemispheres can be removed (and are removed, in operating rooms every day) without substantial specific loss of function.I wish had a picture but the best thing I could find was this summary of different brain functions by Brodmann area. If you take a look through it you can see that the idea that large parts of the non-eloquent brain do not correlate with specific function is quite absurd.
Furthermore, the eloquent brain is called so not because it correlates with a specific function, but because damage to those areas is necessary for regular daily activity. Damage here leads to readily apparent and predictable changes in behavioural output, such as language use or motor control. Damage to non-eloquent areas also leads to predictable changes in behavioral output. However, discerning those changes requires specialized tests because they only manifest under certain conditions, not because there is a poor correlation between anatomy and function. I find it difficult to conceive that anyone, given our current knowledge, would assert this is not the case.
Second, Egnor gives us his standards for scientific proof of a material mind:
Novella has no evidence for a 1:1 correlation between brain anatomy and higher mental function. This evidence is required if materialism is to be supported, because materialism asserts that brain matter is the complete cause of the mind, without remainder. Thus far, for higher mental functions, the remainder is huge, and there is no reason to believe based on the science that a 1:1 reduction of mind to brain will ever be found, especially with regard to higher mental functions such as reasoning.Now think about that for a moment. Egnor is asking not just for a high correlation but an absolute correlation as proof of materialism. There is no margin for errors in measurement, stochastic processes, or individual differences, let alone the limits of current or future technology to accurately measure brain function. Egnor has essentially said no amount of evidence will convince him that materialism is correct. That doesn't surprise me at all nor does it bother me at all, but it would be nice if he just came out and said that rather than imply that some empirical evidence would convince him otherwise. Within biology you never see a correlation of 1.0 even for the most basic functions (I would be very suspicious if I did). But this absolute correlation Egnor looks for as proof of materialism raises some problems when we start looking at non-biological fields of scientific inquiry.
For example, within chemistry we have a decent understanding of how elements interact to form complex molecules. A diamond, a decidedly non-living entity, is a crystalline formation of carbon atoms. It has a predictably structure that is restricted by the covalent bonding pattern of carbon although impurities and defects in the structure are not uncommon. It would seem that the results of cutting a diamond (the material) could be reliably predicted by complete knowledge of the lattice orientation, imperfections, inclusions, etc. However, even with years of experience diamond cutters do not know for certain how a diamond will spit when struck. Does the fact that one cannot use a materialist approach to predict diamond splitting with absolutely certainty mean that a) our imprecision is due to our lack of perfect knowledge (a lack that may exist in perpetuity), or b) there is an additional immaterial essence of the diamond (the form) that is unknowable and ultimately determines what shape the cut diamond will be. It seems improbable that the latter is the case, but I would not be surprised if Egnor believes it is. Frankly not too much he says would surprise me at this point.
Talk about an impossible standard.
I really don't mind when I hear a "god of the gaps" style argument. People are free to fit in their particular non-empirical entity of choice in any gap they want. But the "god of the gaps" accusation is not a comment on the success of current theories to fill in the gaps. It is a comment on the abject failure of god as an explanatory device. I have no illusions that we can attain perfect knowledge and explain all things, but that should not be mistaken as a belief that with perfect knowledge one could not do so in principle. With each new gap that is filled in by a materialist approach to the mind it becomes increasingly unreasonable to assert that the mind can best be accounted for by an immaterial essence. Inference to the best explanation, as fans of abductive reasoning would say.
Image via Xavier Studio