The below post was incorporated into my e-book The Apple of Knowledge. If this interests you, please consider buying my book.
Okay, this blog is not supposed to be focused upon the philosophical question of the mind-brain identity. Next month I am going to start posting on entirely different topics. But permit me one last mind-brain blog post. . . .
How do we know that the mind is the brain? Three reasons:
1. Brain damage. Science has learned, from over 100 years of experience, that brain damage to a specific section of the brain corresponds to a failure in a specific function of the mind. For example, there is a part of the brain which once damaged causes the mind to cease to recognize faces, so a person can see the face of a loved one and not know who they are, and be unable to remember faces. This strongly suggests that the mind is composed of the collection of mental functions of each part of the human brain.
2. Drug effects. Drugs such as alcohol and marijuana have a specific effect upon the mind. These are physical substances which alter the brain. This is what we would expect if the mind is the brain. If the mind were a soul then we would not expect drugs to alter or control it.
3. Sleep, etc. If the mind was a disembodied soul then we would expect it to remain awake while the brain sleeps, not to be controlled by bodily urges such as hunger, etc.
The counterargument is people's anecdotes of out of body experiences and spiritual experiences, but this is adequately explained by hallucinations and wishful thinking.
One last note: I strongly believe that evolution not only changed the human brain, it also added new things on top of the old ones while leaving the old parts relatively unchanged. Thus I think the neocortex is the distinctly human reasoning part of the brain, while the older brain structures remain much as they were in our animal ancestors. This is why the conscious mind can focus and concentrate, but the older parts of the brain have a remarkably short attention span and are easily distracted: back one million years ago the brain needed to quickly react to new stimuli to survive (e.g. by fighting or running away from predators and dangers), whereas in modern man the need to mentally concentrate is key to survival (e.g. learning and developing technology). A lot of people underachieve their intellectual potential by not engaging the distinctly human reasoning part of their brain and instead let the animal part of their brain do most of their cognitive activity, which explains all the people who have short attention spans and do nothing but watch TV and eat potato chips in their spare time, instead of reading great books and thinking deep thoughts. That last part, however, is just my opinion, and is conceptually distinct from the brain-mind identity hypothesis.
