Space City Skeptics

The Official Blog of the Houston Skeptic Society

A primer on the mind-brain debate

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human brainA major contention of the spiritually inclined is that the mind is separate from the brain.  In other words, they believe the brain is simply a biological organ that is in some way controlled by a metaphysical “mind.”  Others believe that the brain is sufficient to explain all that we think, feel, and experience.  In this post, I am going to provide a brief overview of the skeptical thinking of this issue.


A brief note about nomenclature.  Some call the belief in a spiritual mind and a physical brain “dualism.” The belief that there is only the physical brain is sometimes called “materialism.” I prefer not to use this language as the term “materialistic” already has a negative connotation.

Occam’s razor

The default position when deciding between two hypotheses is to initial accept the one that introduces the least amount of variables.  In the  mind-brain debate, it is clear that the a spiritual basis for mind relies on many unproven and arbitrary variables.  In the spiritual basis, you have to introduce the idea of spirit.   Then you have to bring in the idea of how the brain communicates with this spirit.  On the other side, the only variable that has to brought in is the brain itself, and I am pretty sure it exists.


As with every debate, determining reality comes down to which side has the evidence.  The idea of a spiritual mind has no evidence.  In fact, out-of-body experiences and deja vu were formerly thought to only have underlying spiritual causes.  However, these phenomenon have been reproduced under laboratory conditions indicating that they all have underlying physical causes.  Of course modern science has not shown that the brain is sufficient to produce every characteristic that we associate with a human mind.

Quantum mechanics

Whenever a supernatural theory gets challenged, it seems to be that they always fall back on the idea of quantum mechanics. Pick your favorite pseudoscience and some proponent has likely invoked the world of quantum mechanics to explain their unscientific ideas.    The mind-brain debate is no exception.  The problem with using quantum mechanics to explain these pseudosciences is that quantum mechanics operates on a scale that is simply too small.  Such small scale phenomena do not have any appreciable effect on comparably large scale structures like neurons.  These effects are in no way large  enough to explain all of the characteristics that are ascribed to them.

Brain changing the brain

An argument put forth by the spiritual mind proponents is the idea that the brain can’t change the brain.  They claim that only an outside force, such as the spirit, can change our brains.  This line of reasoning is flawed, because we have good evidence that the brain does in fact change itself through experience.  One clear example comes from the process of learning something.  We can see biochemical changes happening in the brain when an animal learns.  Furthermore, we can see a change in the connection of two neurons in a petri dish simply by repeated stimulation of one of the neurons.  These examples show us that the brain can change itself.

Artificial Intelligence (AI)

One subject that invariably comes up when discussing the mind-brain debate is the status of AI.  The spiritual-mind proponent will often ask why we haven’t been able to reproduce a human mind if it is only made out of matter.  The obvious answer here is that the technology to perform such a feat is a long ways away.  Still, the proponents argue that it will never happen.  I guess only time will tell, but we can look at past successes and current technologies as a clue to our future.

deep blueThere was a time in recent memory that some people believed that a computer would never be able to beat a human at chess.  That all changed in 1997 with the victory of IBM’s Deep Blue over Garry Kasparov.  The idea seems ridiculous now, but many said it would never happen.  Such a defeat by a computer shows us an example of unexpected computer success.  In fact, it has been said that Garry Kasparov believed that Deep Blue was cheating because he saw intelligence and creativity in its moves.

Another example of where AI is making steady progress is in what is called the Turing test. Briefly, a computer/program is designed to be able to reproduce written human interactions so accurately that a person could not tell the difference between a real person and the computer when tested.  The test is typically all done through the keyboard so the subject can not tell which is which by sight or sound.  The latest round of testing showed that 3 out of  12 judges were fooled into thinking the program was a human.  Although this might not seem that impressive, the programs have been making impressive and steady gains every year.  This year’s winner was named Elbot and an online version can be found here. Try it out, it is a lot of fun.


This post is a simple overview of the debate between those that believe the mind is controlled by some outside factor and those that believe that the brain is sufficient to produce a mind.  There are numerous other nuances and ideas in the debates that I didn’t bring up (such as common logical fallacies, qualia, free-will, brain injury, etc.), but I think it is clear that on the surface that the physical brain hypothesis holds all the cards.

Written by bort901

December 23, 2008 at 12:59 pm

Posted in Science

One Response

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  1. Oh yeah!?!

    Michael Egnor

    December 23, 2008 at 11:02 pm

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