- Email: [email protected]
Bringing philosophy to neuroscience
Perspectives
See Jones AH. Literature and medicine: García Márquez’ Love in the Time of Cholera. Lancet 1997; 350: 1169–72.
prophylactic suicide, carried out despite his health and the continuing love of his mistress. Against the backdrop of his suicide, the opening pages of the novel detail Urbino’s struggles to deal with the physical and mental losses of his own ageing. He is living through exactly what Saint-Amour feared and wanted at all costs to avoid, but Urbino dares not think of suicide himself, presumably because of his Catholicism. SaintAmour’s act also provides a contrast with Florentino’s passionate resolve
not to commit suicide as a result of his unrequited love for Fermina but to outlive Urbino and woo Fermina again. In triumph over rational gerontophobia, the love of Florentino and Fermina survives “forever” because Florentino can not only endure but also prevail over ageing. The film captures the novel’s ending but greatly diminishes the odds against which it was achieved. García Márquez’ novel has recently enjoyed a renascence on The New York Times paperback trade fiction
bestseller list since being chosen as a featured selection of Oprah’s (Winfrey) Book Club. Just after the US release of the film last month, the novel moved into first place on that bestseller list. Thus, despite its shortcomings, I urge those who have not read the book to see the film, in the hope that they, too, will be motivated to read the novel and appreciate the true depth of García Márquez’ work.
Anne Hudson Jones [email protected]
Oxford University Press
Book Bringing philosophy to neuroscience
The printed journal includes an image merely for illustration
Explaining the Brain: Mechanisms and the Mosaic Unity of Neuroscience Carl F Craver. Oxford University Press, 2007. Pp 272. £27·50. ISBN 0-19-929931-7.
2092
Until fairly recently, philosophers were rather uninterested in—perhaps even scared of—brains. On the one hand, there was the well established tradition of philosophy of mind, concerned with the mental processes of cognition. On the other hand, there were philosophers of science, which generally meant physics, with its formal structure of theories and laws. Biology was seen as a soft science, rich in contingent variety, with no discernible laws. Its one universal theory, that of natural selection, attempts to explain current living processes by their evolutionary history, a process that is anathema to tidy philosophical thinking. And brains are even worse. Evolutionarily constructed, the “organ” of mind and selfhood seems full of paradox. If minds do not float free, but are in some way anchored in brain processes, what is the relation between how we think and the seemingly determinate firing of neurons and release of neurotransmitters? If, as leading neuroscientists increasingly insist, “you are your brain”, then what becomes of my sense that I have freedom to act? Indeed, just what is this “I” that has such sensations over and above “my” brain and body? The problems seem insurmountable.
So the philosophers have begun to move in. Some, especially in the USA, seduced by the lure of the laboratory, have apprenticed themselves almost as glorified technicians to the neurolabs. A few have remained outside, attempting to apply the formal rules of their own trade to the messy field of brain research. Carl Craver is one such, and his book, as he admits,
“So, a tough book, but one that serves to remind us that courses in philosophy should be compulsory for budding neuroscientists.” will not make easy reading for a scientist unversed in philosophical terminology. But it is worth persisting, for the purpose of his early groundclearing chapters is to focus on two major questions: the nature of neuroscientific explanation, and the tricky concept of “levels”. Craver approaches these issues through two main examples: the Hodgkin-Huxley (H-H) equations for action potentials, and the phenomenon of long-term potentiation (LTP), a physiological property of neurons, which was discovered in the rodent hippocampus in the early 1970s by Tim Bliss and his
colleagues, and is now intensively researched, being regarded variously as a physiological analogue of, or mechanism of, memory formation. H-H provides an equation for the changes in voltage that characterise the action potential and goes on to describe a mechanism for these changes in terms of ion fluxes across the axonal membrane, the gating properties of membrane proteins, and the role of calcium ions. Similarly, LTP—a lasting change in the firing properties of neurons—involves, among other things, changes in the activity of particular classes of glutamate receptors in the neuronal membrane, protein synthesis, and various other biochemical processes. Do these biochemical processes cause and explain action potentials and LTP? With certain caveats, Craver argues that they do. That is, to describe a biochemical mechanism that occurs when a physiological (or psychological) process takes place is, he argues, to provide a satisfactory causal explanation of that process. Most neuroscientists would agree, even if it takes Craver a couple of hundred pages to arrive at such a conclusion. However, I have some caveats that Craver only implicitly acknowledges. It
www.thelancet.com Vol 370 December 22/29, 2007
Perspectives
is important to ask, which he does not, what we want from an explanation. If I ask why a motor neuron in my cortex is firing, I can describe the H-H mechanism, or I can describe the antecedent events. For example, information arriving at my retina and then visual cortex of an approaching vehicle, recognition, involving many brain regions, that I am standing in its path, and hence mobilisation of muscles via my motor neurons to leap out of the way. These explanations are equally valid, but at different levels, and have different purposes, but are often confused. I prefer to understand causal mechanisms as those that involve a temporal sequence in which one event or process leads necessarily to another. In the case of the action potential it isn’t that first there is an ion flux and then the potential. The
ion flux is the action potential, but described in biochemical rather than physiological language. If one wants to design a drug to diminish excess neuronal activity (eg, in epilepsy) the biochemistry becomes a necessary level at which to work. If one wants to diminish traffic accidents, it is more important to teach a person to look both ways before crossing the road. That is, explanations have meaning only if one considers their purposes. The problem for tidy-minded philosophers and reductionistically trained neuroscientists is their compulsion to find single-level, fundamental explanations for the phenomena of mind and brain, and to dismiss higher level explanations. Thus, the neurophilosopher Patricia Churchland describes these explanations as mere “folk psychology” that advances in
science will in due course sweep away. Craver is careful to avoid this trap. This is why he calls for a “mosaic” unity in the neurosciences, one that recognises multiple levels of both phenomena and their explanations. Neuroscience is a field of enquiry rather than a single discipline. Craver is, indeed, particularly good on the vexed issue of levels, to which he provides what he calls a “field guide” distinguishing between, among others, levels of nature (eg, molecules, cells, organisms), levels of science (biochemistry, psychology), and levels of theory (LTP, memory). So, a tough book, but one that serves to remind us that courses in philosophy should be compulsory for budding neuroscientists.
Steven Rose [email protected]
In brief Book Death of a healthy diet There’s something for everyone in this book. It combines a travelogue, a real whodunnit murder case, industrial espionage, chemical pollution, organic foods, recipes, historical nutrition, and a biography of a leading World War II scientist, Sir Jack Drummond. James Fergusson switches seamlessly between these genres, all the while maintaining an engaging narrative. Drummond was Chief Scientific Adviser to the Ministry of Food and ensured that during the war years the general nutrition of Britain’s population was as good as it has ever been. He also devised our system of vitamin classification. Drummond, his wife, and daughter were shot dead while on holiday in France, in 1952. Thanks to agrochemicals, the austere wartime rations have now been replaced with enormous quantities of foods in developed countries, but nutritionally our diets
www.thelancet.com Vol 370 December 22/29, 2007
are often poorer. Agrochemicals underlie the main theme of The Vitamin Murders: Who Killed Healthy Eating in Britain? Fergusson investigates whether espionage and Drummond’s role in agrochemicals played a part in his death. He also offers some disturbing examples of how a rather cavalier attitude by governments and industry during the 1940s and 1950s resulted in sustained chemical pollution. As with most history, the importance lies in the lessons that can be drawn with hindsight. Although the chemical industries are more responsible now, similar attitudes are echoed in the push for genetic manipulation of crops and animals. In Drummond’s time it was governments pushing industry to get quick and dirty results to help increase food production to overcome food rationing in Europe; nowadays it is industry cajoling governments into accepting genetically modified
(GM) crops on the basis of dubious data. The GM industry now uses threats about jobs and being left behind in the global marketplace together with highly questionable logic on preventing starvation. As with agrochemicals like DDT, the end result could still be major sustained (or even irreversible) pollution. One weakness of the book is when Fergusson rants a little too much about organic food and chemical additives, but he soon gets back onto Drummond’s story and provides the reader with more food for thought. For those interested in nutrition and what we eat, in the history and misuses of science—and in how our environment and lives can be changed by political and industrial pressures that override commonsense and caution—this is an informative yet entertaining read.
The Vitamin Murders: Who Killed Healthy Eating in Britain? James Fergusson. Portobello Books, 2007. Pp 272. £12·99. ISBN 1-846-27014-6.
Stuart Spencer [email protected]
2093
See Jones AH. Literature and medicine: García Márquez’ Love in the Time of Cholera. Lancet 1997; 350: 1169–72.
prophylactic suicide, carried out despite his health and the continuing love of his mistress. Against the backdrop of his suicide, the opening pages of the novel detail Urbino’s struggles to deal with the physical and mental losses of his own ageing. He is living through exactly what Saint-Amour feared and wanted at all costs to avoid, but Urbino dares not think of suicide himself, presumably because of his Catholicism. SaintAmour’s act also provides a contrast with Florentino’s passionate resolve
not to commit suicide as a result of his unrequited love for Fermina but to outlive Urbino and woo Fermina again. In triumph over rational gerontophobia, the love of Florentino and Fermina survives “forever” because Florentino can not only endure but also prevail over ageing. The film captures the novel’s ending but greatly diminishes the odds against which it was achieved. García Márquez’ novel has recently enjoyed a renascence on The New York Times paperback trade fiction
bestseller list since being chosen as a featured selection of Oprah’s (Winfrey) Book Club. Just after the US release of the film last month, the novel moved into first place on that bestseller list. Thus, despite its shortcomings, I urge those who have not read the book to see the film, in the hope that they, too, will be motivated to read the novel and appreciate the true depth of García Márquez’ work.
Anne Hudson Jones [email protected]
Oxford University Press
Book Bringing philosophy to neuroscience
The printed journal includes an image merely for illustration
Explaining the Brain: Mechanisms and the Mosaic Unity of Neuroscience Carl F Craver. Oxford University Press, 2007. Pp 272. £27·50. ISBN 0-19-929931-7.
2092
Until fairly recently, philosophers were rather uninterested in—perhaps even scared of—brains. On the one hand, there was the well established tradition of philosophy of mind, concerned with the mental processes of cognition. On the other hand, there were philosophers of science, which generally meant physics, with its formal structure of theories and laws. Biology was seen as a soft science, rich in contingent variety, with no discernible laws. Its one universal theory, that of natural selection, attempts to explain current living processes by their evolutionary history, a process that is anathema to tidy philosophical thinking. And brains are even worse. Evolutionarily constructed, the “organ” of mind and selfhood seems full of paradox. If minds do not float free, but are in some way anchored in brain processes, what is the relation between how we think and the seemingly determinate firing of neurons and release of neurotransmitters? If, as leading neuroscientists increasingly insist, “you are your brain”, then what becomes of my sense that I have freedom to act? Indeed, just what is this “I” that has such sensations over and above “my” brain and body? The problems seem insurmountable.
So the philosophers have begun to move in. Some, especially in the USA, seduced by the lure of the laboratory, have apprenticed themselves almost as glorified technicians to the neurolabs. A few have remained outside, attempting to apply the formal rules of their own trade to the messy field of brain research. Carl Craver is one such, and his book, as he admits,
“So, a tough book, but one that serves to remind us that courses in philosophy should be compulsory for budding neuroscientists.” will not make easy reading for a scientist unversed in philosophical terminology. But it is worth persisting, for the purpose of his early groundclearing chapters is to focus on two major questions: the nature of neuroscientific explanation, and the tricky concept of “levels”. Craver approaches these issues through two main examples: the Hodgkin-Huxley (H-H) equations for action potentials, and the phenomenon of long-term potentiation (LTP), a physiological property of neurons, which was discovered in the rodent hippocampus in the early 1970s by Tim Bliss and his
colleagues, and is now intensively researched, being regarded variously as a physiological analogue of, or mechanism of, memory formation. H-H provides an equation for the changes in voltage that characterise the action potential and goes on to describe a mechanism for these changes in terms of ion fluxes across the axonal membrane, the gating properties of membrane proteins, and the role of calcium ions. Similarly, LTP—a lasting change in the firing properties of neurons—involves, among other things, changes in the activity of particular classes of glutamate receptors in the neuronal membrane, protein synthesis, and various other biochemical processes. Do these biochemical processes cause and explain action potentials and LTP? With certain caveats, Craver argues that they do. That is, to describe a biochemical mechanism that occurs when a physiological (or psychological) process takes place is, he argues, to provide a satisfactory causal explanation of that process. Most neuroscientists would agree, even if it takes Craver a couple of hundred pages to arrive at such a conclusion. However, I have some caveats that Craver only implicitly acknowledges. It
www.thelancet.com Vol 370 December 22/29, 2007
Perspectives
is important to ask, which he does not, what we want from an explanation. If I ask why a motor neuron in my cortex is firing, I can describe the H-H mechanism, or I can describe the antecedent events. For example, information arriving at my retina and then visual cortex of an approaching vehicle, recognition, involving many brain regions, that I am standing in its path, and hence mobilisation of muscles via my motor neurons to leap out of the way. These explanations are equally valid, but at different levels, and have different purposes, but are often confused. I prefer to understand causal mechanisms as those that involve a temporal sequence in which one event or process leads necessarily to another. In the case of the action potential it isn’t that first there is an ion flux and then the potential. The
ion flux is the action potential, but described in biochemical rather than physiological language. If one wants to design a drug to diminish excess neuronal activity (eg, in epilepsy) the biochemistry becomes a necessary level at which to work. If one wants to diminish traffic accidents, it is more important to teach a person to look both ways before crossing the road. That is, explanations have meaning only if one considers their purposes. The problem for tidy-minded philosophers and reductionistically trained neuroscientists is their compulsion to find single-level, fundamental explanations for the phenomena of mind and brain, and to dismiss higher level explanations. Thus, the neurophilosopher Patricia Churchland describes these explanations as mere “folk psychology” that advances in
science will in due course sweep away. Craver is careful to avoid this trap. This is why he calls for a “mosaic” unity in the neurosciences, one that recognises multiple levels of both phenomena and their explanations. Neuroscience is a field of enquiry rather than a single discipline. Craver is, indeed, particularly good on the vexed issue of levels, to which he provides what he calls a “field guide” distinguishing between, among others, levels of nature (eg, molecules, cells, organisms), levels of science (biochemistry, psychology), and levels of theory (LTP, memory). So, a tough book, but one that serves to remind us that courses in philosophy should be compulsory for budding neuroscientists.
Steven Rose [email protected]
In brief Book Death of a healthy diet There’s something for everyone in this book. It combines a travelogue, a real whodunnit murder case, industrial espionage, chemical pollution, organic foods, recipes, historical nutrition, and a biography of a leading World War II scientist, Sir Jack Drummond. James Fergusson switches seamlessly between these genres, all the while maintaining an engaging narrative. Drummond was Chief Scientific Adviser to the Ministry of Food and ensured that during the war years the general nutrition of Britain’s population was as good as it has ever been. He also devised our system of vitamin classification. Drummond, his wife, and daughter were shot dead while on holiday in France, in 1952. Thanks to agrochemicals, the austere wartime rations have now been replaced with enormous quantities of foods in developed countries, but nutritionally our diets
www.thelancet.com Vol 370 December 22/29, 2007
are often poorer. Agrochemicals underlie the main theme of The Vitamin Murders: Who Killed Healthy Eating in Britain? Fergusson investigates whether espionage and Drummond’s role in agrochemicals played a part in his death. He also offers some disturbing examples of how a rather cavalier attitude by governments and industry during the 1940s and 1950s resulted in sustained chemical pollution. As with most history, the importance lies in the lessons that can be drawn with hindsight. Although the chemical industries are more responsible now, similar attitudes are echoed in the push for genetic manipulation of crops and animals. In Drummond’s time it was governments pushing industry to get quick and dirty results to help increase food production to overcome food rationing in Europe; nowadays it is industry cajoling governments into accepting genetically modified
(GM) crops on the basis of dubious data. The GM industry now uses threats about jobs and being left behind in the global marketplace together with highly questionable logic on preventing starvation. As with agrochemicals like DDT, the end result could still be major sustained (or even irreversible) pollution. One weakness of the book is when Fergusson rants a little too much about organic food and chemical additives, but he soon gets back onto Drummond’s story and provides the reader with more food for thought. For those interested in nutrition and what we eat, in the history and misuses of science—and in how our environment and lives can be changed by political and industrial pressures that override commonsense and caution—this is an informative yet entertaining read.
The Vitamin Murders: Who Killed Healthy Eating in Britain? James Fergusson. Portobello Books, 2007. Pp 272. £12·99. ISBN 1-846-27014-6.
Stuart Spencer [email protected]
2093