The Argument from Mind-Brain Dependence
by Francois Tremblay
There are some fundamental ontological facts about the concept “god” that derive from some of its basic attributes. A god is said to be Creator of all material existence. But if this is the case, then it cannot be material, given that something cannot create itself.
A god is also said to be a personal being. By definition, personhood depends on consciousness (to whatever extent), the capacity of cognition, the capacity to interact with other persons. All of these things can be subsumed under the more general category of “mind” – a mind of some sort is necessary for personhood.
Some kind of material, computational substrate is a necessary condition for the existence of a mind (whether it is sufficient is a different, irrelevant issue). In humans, the brain is this substrate. We know this principle as a scientific fact, for five reasons. I quote here from The Case Against Immortality, by Keith Augustine.
(F1) The evolution of species demonstrates that development of the brain obtains a corresponding mental development.
(F2) The same principle is demonstrated by brain growth in individual organisms.
(F3) Brain damage destroys mental capacities.
(F4) Experiments and measurements on the brain (EEG, stimulation of various areas) indicate a correspondence between brain activity and mental activity.
(F5) The effects of drugs show correspondence between brain activity and mental activity.
The references are Beyerstein, Barry L. “The Brain and Consciousness: Implications for Psi Phenomena.” In The Hundredth Monkey. Prometheus Books, 1991: 43-53, and Lamont, Corliss. The Illusion of Immortality, 1990.
With (F1) to (F5), we can see that the following conclusion is ironclad :
(1) None of the organic minds we have observed can exist without a brain. (from F1 to F5)
By induction, we obtain :
(2) Probably, no organic mind can exist without a brain.
To be fair, we do not expect a hypothetical god to have an organic mind. So we extend (2) to :
(2b) Probably, no mind can exist without a material, computational substrate.
(3) A god cannot be material.
(5) Probably, gods cannot exist. (from 2b, 3 and 4)
I see two main objections to this argument. For instance, one may object to my extension to (2b), which seems to imply that a computational substrate is material. What if a god was a computational system, without needing to be material at all ?
There is some merit to this assertion, but there are two problems with it. For one, some would object that materiality is a further necessity in order to obtain a mind, and that a computational system alone is not the only necessary condition. While I do not share that position, it is important to realize that the objection would not be a problem at all for such a view.
The second problem is the sheer ad hoc nature of such a construction. How can we say that a non-natural being could be computational ? To be computational requires the existence of parts, and there is no reason to suppose that a non-natural being could have parts. Indeed, the Catholic Encyclopedia argues explicitly against this view on the grounds that infinity cannot be divided. Since the nature of a hypothetical god is meaningless, the objection fails flat. Furthermore, all the computational systems we know are material, so induction can be used here also.
A second objection, which is far more common albeit used to justify the existence of an afterlife, is the existence of such alleged phenomena as OBEs (Out of Body Experiences), NDEs (Near-Death Experiences), astral travel, reincarnation, etc. Given these, we should cast (1) in doubt.
This is not the place for me to examine each paranormal claim. Such a discussion would be not only a waste of space but also futile, since many people have done it with great skill (see for instance “Reincarnation : A Critical Evaluation”, by Paul Edwards, and “Dying to Live”, by Susan Blackmore).
Suffice it to say that any evaluation is comparative, and we must examine both sides of the equation. As I said before, we have the preponderance of evidence represented by (F1) to (F5) to support (1). On the other side, we have a number of vaguely defined, logically dubious, scientifically bankrupt claims. The question therefore becomes : where does the weight of evidence lie ?
Unless one thinks that one of the paranormal phenomena I listed has more evidence than the whole of neuroscience and the evolution of the brain, the answer must be that (1) stays valid. And the current state of scientific research supports that conclusion.
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