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How to Solve the Mind-Body Problem
The mind is the brain. Each mental state -- each hope, fear, thought -- can be identified with a particular physical state of the brain, without remainder. So argues Nicholas Humphrey in this highly readable yet scholarly essay. He offers strong support for his "identity theory" from evolution. His controversial claim is discussed and challenged in commentaries by authors such as Andy Clark ( Being There , 1997), Daniel Dennett ( Consciousness Explained , 1991; Darwin's Dangerous Idea , 1995) and Ralph Ellis ( Questioning Consciousness , 1995). Humphrey rounds off the book with a response to his critics. An excellent short introduction to the mind-body problem and the study of consciousness.
- GenresPhilosophy
112 pages, Paperback
First published April 6, 2000
22 people want to read
About the author
Nicholas Humphrey
42 books67 followersNicholas Keynes Humphrey is an English neuropsychologist based in Cambridge, known for his work on evolution of primate intelligence and consciousness. He studied mountain gorillas with Dian Fossey in Rwanda; he was the first to demonstrate the existence of "blindsight" after brain damage in monkeys; he proposed the theory of the "social function of intellect". He is the only scientist to have edited the literary journal Granta.
Humphrey played a significant role in the anti-nuclear movement in the late 1970s and delivered the BBC Bronowski memorial lecture titled "Four Minutes to Midnight" in 1981.
His 10 books include Consciousness Regained, The Inner Eye, A History of the Mind, Leaps of Faith, The Mind Made Flesh, Seeing Red, and Soul Dust. He has received several honours, including the Martin Luther King Memorial Prize, the Pufendorf Medal and the British Psychological Society's book award.
He has been lecturer in psychology at Oxford, assistant director of the Subdepartment of Animal Behaviour at Cambridge, senior research fellow at Cambridge, professor of psychology at the New School for Social Research, New York, and school professor at the London School of Economics.
Humphrey played a significant role in the anti-nuclear movement in the late 1970s and delivered the BBC Bronowski memorial lecture titled "Four Minutes to Midnight" in 1981.
His 10 books include Consciousness Regained, The Inner Eye, A History of the Mind, Leaps of Faith, The Mind Made Flesh, Seeing Red, and Soul Dust. He has received several honours, including the Martin Luther King Memorial Prize, the Pufendorf Medal and the British Psychological Society's book award.
He has been lecturer in psychology at Oxford, assistant director of the Subdepartment of Animal Behaviour at Cambridge, senior research fellow at Cambridge, professor of psychology at the New School for Social Research, New York, and school professor at the London School of Economics.
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December 23, 2018
This book is an attempt to indicate the way to solve a very knotty problem. Humphrey starts by noting that cognitive scientists 'assume that the human mind and brain are... aspects of a single state.' (p.5) This is already selling the reader short, because there is no evidence to support such an assumption, but let's run with it as a working hypothesis. As Humphrey observes, this assumption would lead to an equation of the form 'mental state, m = brain state, b', and he goes on:
'as experimental science becomes more advanced, we are indeed coming to see that mind and brain are merely aspects of a single state. In particular, brain imaging studies... demonstrate in ever more detail how specific kinds of mental activity... are precisely correlated with specific occurrences of brain activity.' (p.6)
We should notice how Humphrey fails to distinguish here between identity and correlation. The argument is circular at this point, because it is only by adding identity as an assumption that evidence of correlation can also be made to be evidence for identity. But let us continue along this intellectually rickety walkway, and see where it leads. Humphrey's next move is to say, quite correctly, that the identity equation, 'mental state, m = brain state, b', can only be correct if the dimensions on both sides of the equation are commensurable, i.e. if both sides are talking about the same kind of thing. And as Humphrey recognises, this has always been one of the obstacles to an explanatory mind-body theory; the phenomenal and the physical just don't seem to be reducible to the same kind of stuff.
Determined to boldly go where many others have boldly but unsuccessfully gone before, Humphrey sets out to reduce the two sides of the equation to commensurable dimensions. He introduces the term 'phantasms':
'... the subjective sensation of redness, the taste of cheese, the pain of a headache, and so on. These are the mental states that Isaac Newton dubbed sensory 'phantasms'.' (p. 9)
Another confusion has crept in. The sensation of redness, the taste of cheese or the pain of a headache are not mental states, they are the content of mental states. (As Humphrey notes, the term we now use for Newton's phantasms is 'qualia', a term to which Humphrey has an evident aversion, though he does not tell us why.) Humphrey propagates this confusion further by rewriting his identity equation as 'phantasm, p = brain state, b', an obvious error. Before we go any further, let's put this right. We can write down three putative identity equations, as follows:
1) conscious subject = brain
2) conscious mental state = brain state
3) quale (or phantasm) = ?
In fact there seems to be nothing in the brain that equates to the quale or phantasm, because as I have noted, qualia or phantasms are not mental states but the content of mental states, and brain states, being mere configurations of matter and energy, do not have content, a fact which identity theorists tend to overlook. I am not offering this as a knockdown argument against identity theories, merely pointing out that mental content is an explanandum, and that any candidate mind-body theory which fails to explain (a) how we come to experience mental content and (b) how we come to experience the particular mental content that we do in fact experience is failing to meet the criteria for a successful theory. It is true that materialist theories seem at first glance to face the greatest difficulty in providing this explanation, but in my opinion even dualist and mentalist theories struggle in this area, since an explanation of mental content merely by reference to some mysterious mental substance or property does not really count as an explanation. (This is essentially why I am a mysterian. Nobody, but nobody, can explain what conscious mental states actually are.)
On the foregoing somewhat dodgy basis, Humphrey then sets out to modify the two sides of his identity equation with the aim of making them commensurable. He starts by tackling the left hand, 'phantasm' (i.e. phenomenal or mental state) side. Following Thomas Reid, the eighteenth century philosopher, he argues that we should distinguish between sensation and perception: thus when we smell a rose, we experience a sweet smell (sensation) and also perceive the external presence of the rose (perception). In itself this is a reasonable distinction (though we should be wary of reading too much into it when trying to construct a philosophical theory of perception).
Humphrey's concern is with sensation, since it is here, according to him, that we encounter our phenomenal 'phantasms'. He is critical of philosophers who suppose that perception has 'a pseudo-sensory phenomenology' (p. 12), offering instead the thought that 'perception by contrast has to do with judgments about the objective facts of the external world' (p.12). Having marked off his territory of interest, Humphrey then sets about giving an account of sensation which would make it commensurable with the brain activity that correlates with it, and he calls on Thomas Reid again for assistance, quoting a passage in which Reid points out that whereas with statements of perception (e.g. 'I see a tree'), 'the distinction between the act and the object is not only grammatical but real', in the case of sensation (e.g. 'I feel a pain'), the distinction is merely grammatical: 'feeling a pain signifies no more than being pained'.
This is unexceptionable. But Humphrey then goes a step further:
'my own view... is that the right expression is not so much 'being pained' as 'paining'.... I am not sitting there passively absorbing what comes in from the body surface, I am reflexly reaching out to the body surface with an evaluative response - a response appropriate to the stimulus and body part affected.' (p.13)
Humphrey then goes on to list five 'defining properties of the experience of sensation', which he describes in a way that makes them seem analogous to properties of the bodily activity that he claims correlates with the sensation itself. What is noticeable about this list is that it omits the subjective phenomenal quality of sensation - what I have called the 'content' of the mental state of sensing. Humphrey immediately admits as much:
'I acknowledge right away that there is also an obvious disanalogy: namely that, to revert to that old phrase, it is 'like something' to have sensations.' (p.14)
Now of course this is the nub of the matter. A mind-body theory which does not explain how we come to have qualitative experiences is no mind-body theory at all. Humphrey makes one final attempt to address this central issue:
'I believe that ultimately the key to an experience being 'like something' does in fact lie in the experience being like itself in time - hence being about itself, or taking itself as its own intentional object. And this is achieved, in the special case of sensory responses, through a kind of self-resonance that effectively stretches out the present moment to create what I have called the thick moment of consciousness.' (p.15)
If this is Humphrey's idea of being explanatory, then I can only quote Lord Byron: 'I wish he would explain his explanation'. I do not understand what is meant by something 'being like itself in time', nor how something taking itself as its own intentional object explains the qualitativeness of subjective experience, nor what it means to stretch out a moment of consciousness, nor how this is supposed to facilitate subjective qualitativeness. This is the central issue, and Humphrey's response is to meet it with impenetrably gnomic phrases. It just won't do.
Before going on to tackle the right hand side of his identity equation (I shall not follow him in doing that), Humphrey summarises his progressive redefinition of the left hand side:
'Thus the phantasm of pain becomes the sensation of pain, the sensation of pain becomes the experience of actively paining, the activity of paining becomes the activity of reaching out to the body surface in a painy way...' (p. 15)
It should be obvious what is wrong with this: 'the experience of actively paining' is replaced (without comment!) by 'the activity of paining', and in so doing the phenomenal words 'phantasm', 'sensation' and 'experience' have all been quietly dropped. In this sentence, Humphrey seems to be reverting to the bad old materialist habit of sweeping qualitative experience under the carpet.
The rest of the book consists of reactions to Humphrey's theory by various people, followed by a final response from Humphrey himself. The reactions are of some interest, but since the theory itself seems to me to completely fail to come to grips with the mind-body problem, I cannot recommend this book.
'as experimental science becomes more advanced, we are indeed coming to see that mind and brain are merely aspects of a single state. In particular, brain imaging studies... demonstrate in ever more detail how specific kinds of mental activity... are precisely correlated with specific occurrences of brain activity.' (p.6)
We should notice how Humphrey fails to distinguish here between identity and correlation. The argument is circular at this point, because it is only by adding identity as an assumption that evidence of correlation can also be made to be evidence for identity. But let us continue along this intellectually rickety walkway, and see where it leads. Humphrey's next move is to say, quite correctly, that the identity equation, 'mental state, m = brain state, b', can only be correct if the dimensions on both sides of the equation are commensurable, i.e. if both sides are talking about the same kind of thing. And as Humphrey recognises, this has always been one of the obstacles to an explanatory mind-body theory; the phenomenal and the physical just don't seem to be reducible to the same kind of stuff.
Determined to boldly go where many others have boldly but unsuccessfully gone before, Humphrey sets out to reduce the two sides of the equation to commensurable dimensions. He introduces the term 'phantasms':
'... the subjective sensation of redness, the taste of cheese, the pain of a headache, and so on. These are the mental states that Isaac Newton dubbed sensory 'phantasms'.' (p. 9)
Another confusion has crept in. The sensation of redness, the taste of cheese or the pain of a headache are not mental states, they are the content of mental states. (As Humphrey notes, the term we now use for Newton's phantasms is 'qualia', a term to which Humphrey has an evident aversion, though he does not tell us why.) Humphrey propagates this confusion further by rewriting his identity equation as 'phantasm, p = brain state, b', an obvious error. Before we go any further, let's put this right. We can write down three putative identity equations, as follows:
1) conscious subject = brain
2) conscious mental state = brain state
3) quale (or phantasm) = ?
In fact there seems to be nothing in the brain that equates to the quale or phantasm, because as I have noted, qualia or phantasms are not mental states but the content of mental states, and brain states, being mere configurations of matter and energy, do not have content, a fact which identity theorists tend to overlook. I am not offering this as a knockdown argument against identity theories, merely pointing out that mental content is an explanandum, and that any candidate mind-body theory which fails to explain (a) how we come to experience mental content and (b) how we come to experience the particular mental content that we do in fact experience is failing to meet the criteria for a successful theory. It is true that materialist theories seem at first glance to face the greatest difficulty in providing this explanation, but in my opinion even dualist and mentalist theories struggle in this area, since an explanation of mental content merely by reference to some mysterious mental substance or property does not really count as an explanation. (This is essentially why I am a mysterian. Nobody, but nobody, can explain what conscious mental states actually are.)
On the foregoing somewhat dodgy basis, Humphrey then sets out to modify the two sides of his identity equation with the aim of making them commensurable. He starts by tackling the left hand, 'phantasm' (i.e. phenomenal or mental state) side. Following Thomas Reid, the eighteenth century philosopher, he argues that we should distinguish between sensation and perception: thus when we smell a rose, we experience a sweet smell (sensation) and also perceive the external presence of the rose (perception). In itself this is a reasonable distinction (though we should be wary of reading too much into it when trying to construct a philosophical theory of perception).
Humphrey's concern is with sensation, since it is here, according to him, that we encounter our phenomenal 'phantasms'. He is critical of philosophers who suppose that perception has 'a pseudo-sensory phenomenology' (p. 12), offering instead the thought that 'perception by contrast has to do with judgments about the objective facts of the external world' (p.12). Having marked off his territory of interest, Humphrey then sets about giving an account of sensation which would make it commensurable with the brain activity that correlates with it, and he calls on Thomas Reid again for assistance, quoting a passage in which Reid points out that whereas with statements of perception (e.g. 'I see a tree'), 'the distinction between the act and the object is not only grammatical but real', in the case of sensation (e.g. 'I feel a pain'), the distinction is merely grammatical: 'feeling a pain signifies no more than being pained'.
This is unexceptionable. But Humphrey then goes a step further:
'my own view... is that the right expression is not so much 'being pained' as 'paining'.... I am not sitting there passively absorbing what comes in from the body surface, I am reflexly reaching out to the body surface with an evaluative response - a response appropriate to the stimulus and body part affected.' (p.13)
Humphrey then goes on to list five 'defining properties of the experience of sensation', which he describes in a way that makes them seem analogous to properties of the bodily activity that he claims correlates with the sensation itself. What is noticeable about this list is that it omits the subjective phenomenal quality of sensation - what I have called the 'content' of the mental state of sensing. Humphrey immediately admits as much:
'I acknowledge right away that there is also an obvious disanalogy: namely that, to revert to that old phrase, it is 'like something' to have sensations.' (p.14)
Now of course this is the nub of the matter. A mind-body theory which does not explain how we come to have qualitative experiences is no mind-body theory at all. Humphrey makes one final attempt to address this central issue:
'I believe that ultimately the key to an experience being 'like something' does in fact lie in the experience being like itself in time - hence being about itself, or taking itself as its own intentional object. And this is achieved, in the special case of sensory responses, through a kind of self-resonance that effectively stretches out the present moment to create what I have called the thick moment of consciousness.' (p.15)
If this is Humphrey's idea of being explanatory, then I can only quote Lord Byron: 'I wish he would explain his explanation'. I do not understand what is meant by something 'being like itself in time', nor how something taking itself as its own intentional object explains the qualitativeness of subjective experience, nor what it means to stretch out a moment of consciousness, nor how this is supposed to facilitate subjective qualitativeness. This is the central issue, and Humphrey's response is to meet it with impenetrably gnomic phrases. It just won't do.
Before going on to tackle the right hand side of his identity equation (I shall not follow him in doing that), Humphrey summarises his progressive redefinition of the left hand side:
'Thus the phantasm of pain becomes the sensation of pain, the sensation of pain becomes the experience of actively paining, the activity of paining becomes the activity of reaching out to the body surface in a painy way...' (p. 15)
It should be obvious what is wrong with this: 'the experience of actively paining' is replaced (without comment!) by 'the activity of paining', and in so doing the phenomenal words 'phantasm', 'sensation' and 'experience' have all been quietly dropped. In this sentence, Humphrey seems to be reverting to the bad old materialist habit of sweeping qualitative experience under the carpet.
The rest of the book consists of reactions to Humphrey's theory by various people, followed by a final response from Humphrey himself. The reactions are of some interest, but since the theory itself seems to me to completely fail to come to grips with the mind-body problem, I cannot recommend this book.
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