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Sahotra Sarkar, Cambridge, Cambridge University Press, 1998, 256 pages, £45 (hb), £16.95 (pb). Holmes Rolston III, Cambridge, Cambridge University Press, 1999, 416 pages (hb), 432 pages (pb), £42.50 (hb), £15.95 (pb).
Genetics and Reductionism is a careful, clear and systematic account of reductionism and how it operates in the context of genetics. Sarkar distinguishes explanation from reduction– the latter being a type of explanation which bridges realms of inquiry, explaining one set of phenomena in terms of another–and also explanation from prediction. There is a formal treatment of issues around reduction, making clear that explanation lies within the scope of epistemology (how do we know) while determinism is concerned with ontology (what is the case). The substantive issues around reduction are dealt with at greater length, with an account of the assumptions that must be made for an explanation to “work”, an account of the various types of reduction, and a discussion of the problems that arise from making approximations in the course of an attempted reduction. The virtues of reduction are also introduced, especially the generation of fruitful hypotheses that can lead to the development of a field of study, although of course reduction is not always fruitful and unifying hypotheses and insights are not always reductive (for example, evolutionary theory).
Sarkar then tackles three major approaches to the unravelling of genetic phenomena. In chapter 4, The obsession with heritability, he describes, evaluates and finds wanting the usefulness of attempts to measure the heritability of quantitative traits in contemporary human genetics. In particular, while there may be some useful application of (narrow) heritability to plant and animal breeding, he dismisses the claim that measures of the heritability of IQ and psychological traits establish that these can be largely explained by (unspecified) genetic factors. The assessment of heritability makes a number of highly implausible assumptions and, in any case, much variation in heritability can arise simply from variation in allele frequencies. Heritability itself applies only to a specific population, over a specified time interval and in a specified range of environments–it tells us nothing about the contribution of environmental or genetic factors to the phenotype of an individual. Sarkar wonders at the curious motivation that underlies the recurrent fixation of some investigators with this dubious approach to genetic investigation, and the misdirection of molecular genetic research that attempts to build on this shaky foundation. What is it that drives this obsession, with so many possibilities for the political and social abuse of whatever results emerge?
The reduction of phenomena achieved by classical genetics, through segregation analysis and linkage analysis, is then covered in chapter 5. While Sarkar finds Fisher's demonstration of the compatibility of biometry with Mendelian genetics rather problematic (because it involves counterfactual assumptions) this does not really amount to a reduction. Segregation and linkage analyses do amount to a form of reduction, however, although the molecular mechanisms are of course unspecified. It is in this section of the book that I did find a very few minor errors in the detail of some of the case studies presented; fortunately, these were technical points that did not interfere with the case being argued. There are potentially confounding factors in classical genetic reduction, such as the existence of phenocopies and variable expressivity, but it has provided explanations of many phenomena and has generated numerous fruitful hypotheses, some of which can be tested with the newer methods of molecular biology. The limitations of these classical genetic approaches to complex, multi-factorial disorders are also discussed.
The reduction that can be achieved through molecular biology is then contrasted with that of classical genetics. Sarkar argues, convincingly, that both the scope and the methods of these types of reduction are different. While classical genetics employs explanatory models of a purely formal nature–with no necessary relation to chromosomes, for example–molecular biology employs models of macromolecular structure derived from Dalton's model of the atom and Pauling's theory of chemical bonds. Molecular biology does not reduce to fundamental physics or to quantum chemistry, and cannot predict the behaviour of macromolecules (in protein folding or DNA-protein interactions), but it is an empirical fact that its explanations have been powerful and very fruitful despite the crudity of the underlying chemistry. Explanations in molecular biology may fail on empirical grounds if they remain unable to predict macromolecular structures or to account for classical genetic phenomena such as dominance.
The final pages of this book then propose a definition of “genetic” that might well be acceptable to scientists and yet may help to challenge the inappropriate use of the term in the political arena. This definition is that a trait may be termed genetic if and only if three criteria are met:
the trait is under the control of a few loci;
the trait always (that is, in all populations) shows a high expressivity, and
the immediate (RNA and protein) products of the alleles at these loci form part of the biochemical characterisation (that is, description at the biochemical level) of the trait.
Whilst some may contest this definition, and here is not the place to defend it, I would warmly recommend this book to a wide readership among scientists and philosophers. It demonstrates that reduction can make a valuable contribution to understanding in the field of genetics, but that some attempted reductions fail for good reasons and can arise from suspect motivations. The book is clearly written and employs useful accounts of specific genetic phenomena, which will both appeal to the scientist and help to provide important insights into the science of genetics for the philosopher.
The starting point of the second book, Genes, Genesis and God: Values and their Origins in Natural and Human History Genes, and its conclusion some 370 pages later, is that the emergence of order (termed “information” in this book) and of values during biological and cultural evolution is firm evidence for the existence of a Presence (God). In effect, Rolston is presenting an elaborate reworking of Anselm's proof of the existence of God in Darwinian terms: the fact of religious belief proves the existence of God. While I am not doing justice to the argument of the book in such a brief summary, that is its essence.
The structure of the book is clear, with an orderly progression along the path of biological and cultural evolution in the course of its six chapters, culminating in a discussion of religion. Chapter 1 considers the science of genetics and finds evidence of “value” emerging in the course of evolution–in particular, the evolution of complexity is taken as indicating that biology “values” self organisation. This and the subsequent chapter, on genetic identity, present a lot of biological facts as if they supported the author's position, but this was unconvincing and the argument is weakened by a number of erroneous biological statements. The frequent conflation of a science with its subject matter (for example using the word “biology” when what is meant is “life” or “the living world”) was irritating, and the broadening of the use of the word “value” to stretch from “survival value” to “ethical principle” will cause confusion and introduces inappropriate teleology. Rolston's argument against the application of the word “selfish” to DNA or the gene, as in The Selfish Gene is literalistic and comes across as pedantic. I am no supporter of Dawkins, but the arguments marshalled here against his position are not convincing.
Chapter 3 argues that the genetic processes of evolution have enabled the human species to develop cultures that evolve (largely) independently of the genetic constitution of the relevant individuals. Cultural phenomena constitute a different order of complexity from biology, and cultural events are not determined by the underlying biological organisation (although they may be constrained by it). An infant is born with the capacity to learn any existing human language and to adopt any pattern of behaviour–we are not determined by our genes to speak Swedish as opposed to Swahili, or to play the guitar as opposed to the sitar. Although the fitness of different genotypes may vary with the culture and the history of the group into which a child is born, human history cannot be reduced to biology. There is a lengthy discussion of the limitations of biological explanations of cultural phenomena.
Rolston then examines science, addressing a range of questions in the philosophy and sociology of science. The reflexive nature of science–the human mind peering backwards to examine the processes that led to its own creation–is considered. Parallels are drawn between the growth of scientific knowledge and evolution, and between genetics and language, but in both cases they are pushed further than is useful. The relationship between “facts” and “theories” is made explicit, giving due importance to the (often implicit) framework within which facts are asserted and understood, and the relationships between theories of natural selection and the organisation of capitalist societies are presented. The argument later in chapter 4, against the use of sociobiological explanations to account for human behaviours, is presented well in parts, but when Rolston suggests that the fitness (reproductive success) of sociobiologists be measured to assess the truth of their doctrines, I feel that he has scored a good debating point but one which adds little to my understanding.
Chapter 5 argues that ethics is a distinctively human concern, and considers the extent to which this concern could be accounted for by evolutionary psychology and sociobiology–the alternative, implicitly, being that one must resort to a deity in order to “explain” ethics, especially altruism. The complexities of the kin selection account of ethics include the cultural processes now in operation that generalise our concern for others to include those who are not close relatives. Rolston reviews a wide range of ideas about the reproductive success of different behavioural strategies (personalities). Our tendency to altruism must have evolved, however, long before our current mass society–indeed, long before even mediaeval society– when travel was infrequent and often related to essential trade so that the stranger/visitor would often be helpful to the host. So the argument that today's ethical conduct is not explicable as kin selection, does not demolish the plausibility of the view that the mental processes leading to such altruism evolved through natural selection in the past. Furthermore, given that Rolston has argued (sensibly) that culture is not determined by biology, it is strange that he does not seem willing to accept that some cultural behaviours may escape from biological determinism and take on the force of their own logic. Commitment to a cause such as conservation may not be to one's personal biological or reproductive advantage–although it could be, if one met a mate at conservation meetings–but the strong biological selfishness that “should” be present if behaviour were controlled simply by evolutionary motivations could plausibly be displaced by the internal logic of ethical concerns that have also arisen through an evolutionary process.
There are parallels drawn in this chapter between sociobiology and psychoanalysis because both can be wielded to account for any observed pattern of behaviour but neither can predict specific future behaviours.
The final chapter starts with nonsensical hyperbole–the claim that there are more synapses in one human brain than there are atoms in the universe–but then settles into an evolutionary account of religion. Is religion so widespread because it promotes fertility or because it emerges as a byproduct of intelligent self consciousness? Rolston points out that many religions do have a focus on fertility, but I doubt that the belief systems of modern religions have had much evolutionary impact. Any evolutionary advantage of a propensity to religious belief will either be a general, intellectual benefit or will have developed in the remote, preliterate past. The lengthy argument asserting that world religions constitute counterevidence to sociobiology cannot (and does not) lead to any convincing conclusions. In the discussion, however, Rolston raises a fascinating question. If religion is neither a biological mistake nor a necessary epiphenomenon of self consciousness, might it have been required in the past as a mechanism for the cultural transmission of a society's accumulated wisdom? He also raises the interesting idea that our minds need to work accurately in relation to practical matters but that it may be to our biological advantage for them to promote comfortable delusions in the inner life of the imagination. Perhaps religion is an opiate . . .
In so far as the book has a conclusion, it is that order and values emerge from evolution and that this process requires a supernatural helping hand rather than mere Darwinian selection. The length of the book and its style–as if it were the transcript of the Edinburgh University Gifford lectures (1997-8) from which it originated–do not encourage me to recommend it. It develops a number of interesting arguments, but it does read as if the conclusion had been fixed (predestined) long in advance. It is therefore difficult for me to recommend this volume to a wide readership.
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