Philosophical Foundations of Neuroscience. P. M. S. Hacker

Foreword to the First Edition

       Denis Noble CBE FRS hon FRCP

      This book was simply waiting to be written. The reductionist agenda in biological science has generated so many conceptual difficulties that someone, sometime, had to analyse these problems in depth from outside the reductionist viewpoint. That a neurophysiologist and a philosopher should combine to do so is also a sign of the times. As biology moves on to address the complexity and extraordinary subtlety of life, now that it has broken it down into its smallest pieces, we will find this kind of combination of skills and ways of thinking even more necessary. As the authors make clear, philosophy (at least in the analytical form practised here) and empirical science are not in opposition. Rather they deal with different kinds of question. Yet, since a conceptual scheme is necessary to any fruitful experimentation, we cannot avoid asking both kinds. Keeping a clear head while we do so is not as easy as it may seem!

      I must issue a warning: this book is highly controversial. Some of my scientific colleagues will strongly challenge, and will surely be deeply provoked by, the claim that neuroscience has frequently and systematically confused conceptual and empirical questions. To them I would say, first, that the authors clearly recognize the brilliance and phenomenal achievements of the scientists whose conceptual work they analyse. This is emphatically not a book debunking experimental science, any more than the fact that most physiologists now dismiss the dualist philosophy of Sherrington or Eccles detracts in any way from recognizing the immense significance of their scientific achievements. We find it perfectly possible to admire the experimental and associated analytical skills while wincing when we see how completely trapped they were in their outdated and indefensible philosophical position.

Second, I would appeal for some patience and humility. Patience, because as a physiologist who has interacted with (and published with) professional philosophers of various persuasions for over 40 years,¹ I have to say that I find scientists unthinkingly debunking philosophy more often than the other way round. Humility, because the issues are of the utmost social importance. Some of the claims of reductionist science are not only conceptually incorrect or even unintelligible, they have major social implications. The words we use, the concepts by which we analyse and present biological discovery, deeply affect the way in which we see ourselves as human beings. For that reason, if for no other, a critical debate is necessary. The authors of this book have thrown down a major challenge in that debate.

The controversial nature of this book arises because the particular reductionist philosophical position it criticizes is very widely held today within the scientific community ( and also by some well-known philosophers). Moreover, for most of them, this position is a methodological necessity, perceived to be the only paradigm for science to successfully explain things. The first reaction to the counter-argument, as presented here, will be to protest that somehow science is being (unnecessarily? ) circumscribed; that some problems are, as it were, being taken from its grasp. I would argue the other way. The first step to scientific progress is to ask the right questions. If we are conceptually confused, we will ask the wrong questions. The authors illustrate this in detail with many examples.

      It is hard to escape the confines and confusions of the culture in which one finds oneself. The history of philosophy shows that, just as much as the history of science. The central appeal of this book is to throw off the remaining legacy of the Cartesian confusions, first expressed as a duality of mind and body, but latterly expressed as a duality of brain and body. The authors show that, although the first required belief in a non-material substance, while the latter is wholly materialistic, many of the conceptual problems (essentially those of the ‘ghost in the machine’) are the same. For our dualist predecessors the ghost was an actual immaterial substance, for us it is ‘the “I”’ (or ‘inner eye’ or whatever) that ‘sees’ the qualia that ‘form our experience’. This is what may lead us to ask which group of cells, or even which neurone(!), is doing the ‘seeing’. The point here is that simply replacing ‘I’ or ‘inner eye’ by the brain or a part of the brain doesn’t avoid the problem.

      The key to understanding the confusions here lies in an analysis of the logical conditions for ascribing mental and psychological properties. This is not easy. It involves one of the most difficult of twentieth-century philosophical ideas, that of the ‘private language argument’: what it is to say things like ‘I feel pain’ or ‘I see red’. I struggled through the ramifications of this argument many years ago before writing my own contributions to the philosophy of biology. I wish I had had the benefit of the relatively easy path that Bennett and Hacker have provided. Even those who fundamentally disagree with their arguments ( and I look forward to seeing them engage in debate) must surely acknowledge that this is a sustained and valuable exposition of an important and influential philosophical position.

      Although I would describe that position as philosophically radical (in the correct sense of that word: going back to basic roots and eradicating those that shouldn’t be there), it is often dismissed by scientists as conservative because it may appear to restrict using language in new ways. Yet, they would argue, science cannot advance without doing that. And what better way to achieve it than to start with metaphor or façons de parler, consolidate with dead metaphor (metaphors that become part of everyday language – constructivists argue that that is the way language evolved) and finally end up with a change in our conceptual scheme? Indeed, why not, if that is what will enlighten us, lead us into new conceptual territory, formulate new theories. But there is a simple test for whether that could work in any particular case. For each such metaphorical (or similar) change in use or meaning, or novel piece of terminology (such as ‘qualia’ or ‘memes’), imagine stating its opposite, and then ask whether any conceivable experiment could test empirically between the two. The deep problem for many ‘novel’ concepts and language uses in reductionist approaches is that this test totally fails. The novel use of language is then not so much a scientific as a political or social tool. If you doubt this, try imagining an experiment to test between the existence or non-existence of qualia. Or for whether or not the brain makes representative maps (which are not homunculi incidentally). Or for brain states that ‘explain’ rational thought (rather than being a necessary physical basis for its existence). Surely we should only introduce new terminology where, as with quarks and black holes, we provide the empirical criteria for determining their existence?

Perhaps the problem for many scientists is to imagine what would happen if we abandoned the universality of the reductionist approach. For sure, the nature of science would change. But so it should! We would have to recognize that causation and explanation do not always run upwards from lower to higher levels. And, surely, at a time when we have already come to understand the extent to which causation runs in the opposite direction ( higher-level states in biological systems even influence something as fundamentally lower-level as gene expression), how can we possibly imagine that we will progress without recognizing the validity of explanations at all levels? One of the criteria for determining the level at which explanation succeeds is to ask what can sensibly be ascribed at different levels. It does not make sense to look for explanations at levels lower than that for the applicability of the relevant predicates.

      This is particularly true of rational behaviour, including the use of language. The argument is basically very simple. We cannot, coherently, deny our own rationality. Otherwise we would have difficulty meaning what we say or being convincing in saying it, which is precisely what happens in the sad cases of those

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