The problem is that there a good deal of evidence against such thinking. I've discussed some of these items before, but let's look at some new items that have been discussed in the news.
One interesting case recently reported was that of a woman who has no cerebellum. The cerebellum is known as the “little brain,” and is located near the middle of the brain. But in terms of the percentage of brain cells found in the cerebellum, it is misleading to say the cerebellum is the “little brain.” According to this scientific paper, the most recent estimates are that there are about 22 billion neurons in the cerebrum (the outer part of the brain), and 101 billion neurons in the cerebellum. So as the cerebellum has most of the brain's neurons, we might expect that this woman with no cerebellum was completely dysfunctional.
But actually, it turns out that the woman without a cerebellum merely suffered from mild mental retardation. She was able to walk and talk, and had even got married and had a daughter. How could that be: losing 80% of your brain neurons produces only mild mental retardation?
Another interesting case recently reported is that of an 88-year old man (identified as H.W.) who tested very well on a test of mental functioning, getting the maximum possible score of 30. But it was found that the man had no corpus callosum. The corpus callosum is the main part of the brain that links the two brain hemispheres. As an article reports:
Given the importance of the callosum for connecting the bicameral brain, you’d think this would have had profound neuropsychological consequences for H.W. In fact, a detailed clinical interview revealed that he’d led a normal, independent life – first in the military and later as a flower delivery man. Until recently, if H.W.’s testimony is to be believed, he appeared to have suffered no significant psychological or neurological effects of his unusual brain...Brescian and her colleagues conducted comprehensive neuropsych tests on H.W. and on most he excelled or performed normally. This included IQ tests, abstract reasoning, naming tests, visual scanning, motor planning, visual attention and auditory perception.
The same article refers us to another case of a boy named E.B. who had surgery to remove almost the entire left half of his brain. But he underwent rehabilitation, and “EB's language fluency improved remarkably over the ensuing two to three years until no language problems at all were reported at school or in the family home.” Now how is that possible? If the light (consciousness and intelligence) is all coming from the 100-watt light bulb (the brain), how do you get almost 100 watts of light when you slice the light bulb in half?
Scientists have a kind of lame phrase to try to describe such things. They call it brain plasticity. Brain plasticity is supposed to kind of mean: if one part of the brain goes down, some other part will take over its work. It's basically a kind of non-explanation rather like saying: the brain can keep working pretty good even if you yank out most of its neurons. I guess now we're forced to accept a doctrine of “radical brain plasticity.”
But how can we explain such a thing? Through Darwinian natural selection, perhaps? I can imagine the explanation:
Through the blind process of natural selection, humans slowly developed radical brain plasticity, to help them survive and flourish during all those times about 30,000 years ago when many people were losing half of their brains because of brain surgery.
Oops, that doesn't quite work, does it? That's because about 30,000 years ago, when humans were shuffling around in caves, there was no brain surgery. It seems hard to explain the origin of “radical brain plasticity” giving any reasons relating to natural selection. From the standpoint of survival of the fittest, nature shouldn't care about about helping out the occasional person with a brain defect such as being born without a cerebellum. If Darwinian evolution has 100 healthy brains and 1 defective brain, in theory its attitude should just be: I don't care about the deficient brain – let the fittest survive and reproduce. That's the gist of natural selection – let the weak be damned, and let the strong flourish. So how exactly can we account for the origin of this “radical brain plasticity”?
It's very hard to explain such a thing under conventional ideas that the brain is the light bulb and consciousness is the light. Drastically different ideas may be needed, including some new brain/consciousness model that may be compatible with phenomena such as near-death experiences, a phenomenon quite incompatible with the brain/light-bulb model of consciousness.
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