by Matt Slick
Is the mind an emergent property of the physical brain, and if so what does that mean? In order to answer the question we first need to define our terms. A property of something is its attribute, its characteristic quality or feature such as the hardness of a rock, or the viscosity of a liquid.
An emergent property is a characteristic or feature that emerges when different components are joined. The property that emerges does not exist within the individual parts themselves, but comes into existence when the parts are combined. So, if we were to have a line on a piece of paper, that line possesses the property of straightness. If we were to arrange three of them together in the form of a triangle, then the emergent "property" of the three separate lines thus combined is that of "triangleness." Likewise, life is considered an emergent property of the numerous biological chemicals and neuro-wiring that have a complex arrangement. Therefore, with the same logic, the mind is sometimes considered an emergent property of the physical brain.
Such a conclusion is based on materialism, the view that the physical realm is all there is. If the mind is a necessary emergent property of the complex biological structures of the physical brain, then the mind is a dependent property of the physical brain. When the physical brain ceases, the mind also ceases.
But there are problems with this position.
There is no known test by which such the proposition that the mind is an emergent property of the physical brain can be tested. In other words, to say the mind is an emergent property of the brain is a guess.
Furthermore, if the mind is an emergent property of the physical brain then it must necessarily be dependent upon the physical brain and also be restricted to the laws of physics. This would mean that "logical" conclusions the mind would make cannot be trusted to be true since such conclusions are restricted to the properties of the physical brain and its particular neurochemical wiring. But, what do we do when one brain disagrees with another brain? If neurochemical wiring produces the mind which is, supposedly, rational, then how is truth to be determined? How could anyone then justify the idea that any logical deductions would actually be correct, since the thoughts of that mind are restricted to and must work in concert with the physical limitations of the physical brain? Is there any known mechanism by which one chemical state in the brain produces proper logical inference?
And, how could free will be defended rationally? At best we would only have the illusion of free will since all choices of the mind would be required to operate under physical laws. We would have to ask how physical laws produce free will. Since the physical laws govern the physical brain, and the mind is restricted to the brain, then how can such an idea rationally support free will?
So, the idea that the mind is an emergent property of the physical brain cannot be determined to be true since we know of no test to verify it, and when examined logically it becomes ultimately self-refuting because from such a position we cannot trust our own judgments nor freedom of will.