Brains and minds: science in the clear

Graeme Mitchison
5 June 2009

Jane O'Grady castigates neuroscientists for confusing brains and minds. Undoubtedly she is right to detect slipshod use of language, and she is also right to worry about the unattractive and somewhat sinister rush to commercialise the products of brain scans. However, I would argue that neuroscientists are not quite in the grip of the conceptual delusions she diagnoses. I would also say that the contention of the leading quote, that confusing mind and brain "leads to a dehumanised world and a controlling politics", is debatable. It is not confusing mind and brain that leads this way: it is looking deep into the puzzle of how brain and mind states are truly related.


This article is a response to Jane O'Grady's Can a machine change your mind?

Graeme Mitchison is a scientist based in Cambridge, UK who has worked in fields including sight, bio-informatics and quantum information theory.

Let me begin by saying that, in my view, neuroscientists do not believe in the identity of brains and minds. They may believe that mental states are determined by patterns of neuronal activity, so one ought in principle to be able to predict the mental state of a person from a detailed and compendious enough account of their neural activity. However, since much brain activity never surfaces into consciousness, brain states cannot be in one-to-one correspondence with mental states. And even if they were, the claim that brain and mind states are identical is so bizarre that only a philosopher could have thought it up. Brain states are clearly states of matter and mind states are states of perception or feeling.

Neuroscientists might slip between mental and neural language too easily, as in saying "the subject is seeing a triangle" when all they mean is that there is a triangle-shaped pattern of activity in primary visual cortex. But they don't mean "the brain state is the percept of a triangle". I speak from experience, having been a subject in an experiment where I was shown a triangle while my brain was scanned, and the experimenter happily used somewhat imprecise language but was no identity theorist (I wouldn't let my brain be scanned by an identity theorist).

Of course, triangles are easy enough to map onto visual cortex. But complex mental events seem much more elusive. To quote Jane O'Grady: "Given what is called the holism of the mental, a holism both of abstract belief systems, and of concrete, personal life histories, you couldn't alter either just by tampering piecemeal." However, most phenomena seem holistic before we understand and anatomise them. Embryology seemed an extraordinary series of coordinated processes that could not be disentangled. Yet we now know to some extent how it evolves through cascades of gene switches, which gives us far greater understanding and control. Why shouldn't the same eventually be true of the complex neural activities that underlie beliefs? (I realise that that "eventually" is the "just a matter of time" that Jane O'Grady deplores. But what is one to say? Science does advance, and usually much faster than anyone would have guessed.)

Suppose we succeed in understanding brains and in correlating neural activity with mental events. To do this we will probably have to explore the nature of beliefs and feelings, and map biography in all its detail onto the memory structures of individuals. Isn't it this aim that raises fears of dehumanising and political control? If so, it is not the confusion of minds and brains that we need fear: it is getting deeper into how the brain works and how it relates to the mind.

Let me end by pointing out that our speech organs are driven by output from motor areas of the brain. Although this process is extremely complicated, it is surely possible in principle to accurately predict utterances from the firing of certain sets of neurons. Now it is tempting to think that when we talk about thoughts and feelings we are somehow reporting on the mental world: speech is the medium of philosophers, and seems to transcend the technology of science. Yet our speech is just another kind of brain scan, translating certain neural blips into sound. So, why should a philosopher be happy to study speech activity patterns yet contemptuous of the potentially much more informative patterns seen in brain scans? The puzzle of minds and brains only deepens when we realise that we have been decoding brain scans since the beginning of human history.

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