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Materialist Neuroscience and an Iron Spike through the Brain


P.Z. Myers over at Pharyngula has responded to my recent

Myers raised the example of Phineas Gage and I believe that the example of Gage is important. The issues raised by brain disease and injury cause real problems for the view that the human mind is entirely an emergent product of brain matter.

Phineas Gage was a railway worker in the mid-19th century who suffered a severe brain injury when an explosion drove an iron spike through his brain (diagram above). He survived the injury, but his personality changed considerably. Prior to the injury, he was sober and hardworking. After the injury, he was profane and shiftless. The change in his personality was attributed to the injury to his frontal lobes, and the case stimulated much interest in the neurology of behavior and personality.

The changes in Gage's personality from the brain injury raise serious problems for the materialist theories of the mind. Gage's associates and family realized that his behavioral changes were 'not him', and his behavior was 'not him' in a way that diminished his personal responsibility for his actions. That, is, they realized that the brain injury left him with immoral judgment, not just different judgment. And the observation wasn't just that his judgment was less effective or comported less with reality, but that it was morally wrong in ways that it had previously been morally right. They recognized, at the same time, that Gage was less culpable for his ideas and actions after the injury.

Yet if the mind were just an emergent property of brain matter, Gage's personality after the injury would have been just as much 'him' as his personality before the injury. If Gage's mind were merely the product of brain matter, then Gage's behavior before and after the accident were both the 'real' Gage. It was different behavior, of course, just as Gage had different brain matter, and perhaps behavior that was more or less effective at achieving certain goals, but equally culpable and equally real. A materialist has no basis for assigning either the pre-morbid or the post-morbid behavior to the 'real' Gage or assigning a moral status to either. Moral value isn't a property of mere configurations of matter. Matter can't be 'moral' or 'immoral'.

Yet we all (even materialists!) intuitively recognize that there are differences in culpability, and thus in intent, in the presence of organic brain disease. When we are free of brain dysfunction, we are the 'real' us, and when we have brain dysfunction, we aren't the 'real' us. If we suffer from serious brain disease, we may even be 'not in our right mind'. This forms the basis for the McNaughton Rule, which is the Western legal principle that criminal culpability is diminished if the individual has a brain disease that impairs his ability to distinguish right from wrong, or impairs his ability to act in accordance with that judgment. But organic brain disease is just 'different brain matter', and if the mind is entirely a secretion of the brain, then behavior arising from brain disease is just a different secretion, with no different moral status. Green bile is no more 'moral' than yellow bile. It will not avail to claim that organically 'healthy' brain tissue is what gives rise to virtue, and organically 'diseased' brain tissue is what gives rise to evil. A healthy genius may murder an elderly man with Alzheimer's disease who was offering to do his killer a favor; in this case, the virtuous idea arose in the diseased brain, and the evil idea arose in the healthy brain. The virtue or evil of an idea is not determined by the health or structure of the brain tissue associated with it.

If one accepts the materialist paradigm, mental 'secretions' may differ in form, or effectiveness in perceiving reality, or effectiveness in acting, etc, but no mental 'secretion' is more morally culpable than another. Materialists implicitly assert that the McNaughton Rule is nonsense. If materialism is true, then there are no differences in moral culpability. None of us is in our 'right mind', we're just in different minds at different times, depending on the contemporary condition of our brain matter.

What Myers is arguing, perhaps without fully realizing it, is that all of humanity's notions of moral value and culpability are nonsense, because he claims that mere configurations of matter are the entire cause of ideas and of personality. Values and culpability cannot be ascribed to matter itself, and values and culpability cannot be ascribed to ideas and personality if the mind is caused by matter alone.

The problem of free will and culpability is devastating to a deterministic theory of the mind. In the very act of discussing the mind, we presume that our opinions aren't determined wholly by chemistry and physics. We think that our opinions are true, in a metaphysical way, and are not merely chemical reactions. By promoting materialism as true, strict materialists must implictly claim exemption from their own theory of the mind. If materialism is true, the idea of materialism is merely a particular configuration of neurochemistry and brain matter. Just as materialists attribute the changes in Phineas Gage's behavior entirely to the material changes in Gage's brain caused by the iron spike, the materialistic theory itself is then a consequence of changes in the materialists' brain tissue-- a sort of ideological iron spike. From the materialist perspective, when P.Z. Myers reads Dennett or Dawkins or Churchland, Myers' new ideas are caused merely by electrochemical reactions to the photons reflected from the pages of the books that cause changes in Myers' brain. Just as photons from books cause material changes in Myers' brain which cause changes in Myers' ideas, the iron spike from the railway explosion caused material changes in Gage's brain which caused changes in Gage's ideas. Materialist books and the electrochemical brain processes they give rise to are more nuanced than Gage's iron spike, but, from the materialist perspective, they are qualitatively no different. They are both material causes of changes in brain matter and thus of changes in ideas. According to Myers' strict materialist theory of the mind, books and iron spikes both cause their effects on the mind in the same way: by rearranging brain matter. Rearranged brain matter isn't 'true' or 'false'-- it's just different. And the opinion that certain arrangements of brain matter give rise to true ideas is itself just a different arrangement of brain matter.

If ideas are caused entirely by brain tissue, Myers has no more claim to truth after reading books about materialism than Gage had a claim to truth after his brain was punctured by a spike. All opinions are just reshuffled brain matter-- including the idea that opinions are just reshuffled brain matter! As philosopher John Searle notes "...the conviction of our own freedom is inescapable. We cannot act except under the presupposition of freedom." (1) The materialist theory of the mind, as a deterministic theory that maps our thoughts entirely to our neurochemistry and to our brain matter, reduces to nonsense.

The materialistic/deterministic understanding of the mind is self-refuting, and is inconsistent with our intuitive and nearly universal understanding of personality and of moral culpability. But I wish that I could say that Myers wasn't entirely wrong. I like the analogy between materialist ideology and an iron spike through the brain...

(1) Searle, John R.: Mind. A Brief Introduction. In Fundamentals of Philosophy Series Oxford University Press 2004 p 164