Philosophy, Instinct, Intuition: What Motivates the Scientist in Search of a Theory?

Transcription

1 Biology and Philosophy 15: , Kluwer Academic Publishers. Printed in the Netherlands. Philosophy, Instinct, Intuition: What Motivates the Scientist in Search of a Theory? PETER J. BOWLER School of Anthropological Studies, The Queen s University of Belfast, Belfast BT7 1NN Northern Ireland Abstract. This article questions whether philosophical considerations play any substantial role in the actual process of scientific research. Using examples mostly from the nineteenth century, it suggests that scientists generally choose their basic theoretical orientation, and their research strategies, on the basis of non-rationalized feelings which might be described as instinct or intuition. In one case where methodological principles were the driving force (Charles Lyell s uniformitarian geology), the effect was counterproductive. Key words: non-rational methods, research strategies Metaphysics is the finding of bad reasons for what we believe on instinct. F.H. Bradley, Appearance and Reality (1893) The first draft of this article was presented to a workshop on the relationship between science and philosophy organized by David Hull at Bellagio, Italy, in July At first I was at a loss to think why David invited me to the workshop, but my suspicion is that he had a behind-the-scenes agenda: he wanted me to act as a devil s advocate because he knows that I am very suspicious of the claim that scientists routinely take philosophy into consideration, at least when engaged in the creative act of theory-construction. For obvious reasons, I shall not try to maintain that scientists don t get involved in debates on philosophical issues. Clearly they do: but do they engage in such debates while they are actually putting together a new theory or do they put the theory together and then begin to worry about how to defend it on philosophical grounds? My suspicion is that the latter is far more often the case than the former. And on the rare occasions when they do take philosophy seriously, it does more harm than good. In this brief outline I want to indicate some of my reasons for believing this, and to ask what if not philosophical argument

2 94 actually shapes the way scientists confront the world of observation and experiment? Before we go any further, we need to unpack the possible meanings of the term philosophy in this context. The most obvious, and I assume the one that David Hull was primarily thinking of, relates to what we might call the philosophy of science, which includes debates over the nature of scientific knowledge and the structure of the scientific method. But we also use the term philosophy to relate to those more fundamental constraints on a scientist s thinking conventionally called world view, which involve very deep commitments about the ultimate nature of reality. I want to defend my position that philosophy is often only a secondary issue at both of these levels, although the two will involve very different kinds of argument and evidence. Putting it crudely, at the level of the philosophy of science, I suspect that scientists do their research in the way that seems appropriate to the situation they confront at the moment. They just know what makes a sensible way of proceeding, and will engage in methodological debate only in order to fend off challenges by those who think another approach is more fruitful. Their preconceptions about what makes an appropriate methodology can be shaped by a number of factors. One factor is the task in hand; the very nature of the problem may determine how you think you should go about tackling it. More fundamentally, though, methodology is dictated by theory: a certain kind of theoretical approach will dictate how the evidence is to be handled and hence predetermine methodology. In this sense, the deeper level of philosophical commitment (word view) shapes the theory and hence the methodology. But at the deeper level too I have problems, because I suspect that any human being s deep commitments are a reflection of their personality type, or of habits engendered by their social and intellectual environment, with rational argument being brought in to defend positions that are staked out before they even began to think about the issues. What I am thinking of here is not the detailed relationship of theory to evidence, but the conceptual structure of the theory itself: Richard Owen s conviction that there was an underlying unity of organic form, Darwin s willingness to see evolution as an essentially open-ended process. These commitments certainly imply what might be called philosophical considerations. They depend on choices at the deepest level of world-view, and at this level a scientist s thinking will indeed be reflected in philosophical concerns, although it may also reflect religious and ideological factors. The issues raised by the theory will certainly be debated at all these levels but does rational argument in any of these areas actually determine why the individual plumps for a particular world view? This raises what I have always assumed to be the essence of Bradley s adage quoted above: at this deep level, choice depends

3 on personality-type, or perhaps deeply-ingrained habit, as much as anything. Scientists, like everyone else, find themselves believing that things just have to be this way they search for the philosophical, religious or empirical justifications after they have recognized their basic orientation on the issue. Some people just can t bear to believe that we live in a chaotic universe, others find the prospect exciting. At this level philosophy, like everything else, comes in after the decision has already been taken. Philosophy is supposed to differ from religion and ideology in the sense that it should always involve rational argument. Religious belief usually arises from faith before it becomes the subject of rational apologetics. But a philosophical position is one that is supposed to have been arrived at by rational argument, and to some extent this is obviously true. No one becomes a philosophical idealist without having worked through the arguments that show how evidence for the material world is constructed from mental sensations. But at the level of world view, philosophical positions can arise from deep feelings unsubstantiated, at first, by rational argument. To repeat the example mentioned above, some people are just certain that we live in a rationally-ordered world, whatever the evidence, while others are more comfortable with the possibility that nature allows a limitless and unpredictable fecundity of structures. These two positions may then be justified by religious, philosophical or scientific arguments but in each case the position is taken up first, and the arguments are then constructed to support it. In biology, at least, those who feel that the variety of nature is a superficial overlay imposed on a deeply ordered foundation of reality have often been philosophical idealists or exponents of a certain view of the Creator but they do not invariably take up those positions, and in many individual cases one is left with the strong feeling that the world view is based on something more fundamental (in their own convictions) than anything subject to rational argument. One line of evidence suggesting that deep commitments seldom arise from rational argument is the fact that they are often made remarkably quickly, almost like a gestalt-shift in the scientists thinking. Thus Darwin seems to have transferred his allegiance very rapidly from traditional creationism to a fully evolutionary word view shortly after he returned from the Beagle voyage. Such sudden changes certainly do not imply that philosophical considerations played no part in the conversion: reading and thinking done in the preceding years would help to create the mental framework within which the transition took place. But the suddenness of the final decision does not suggest that a long process of careful reasoning was involved in the final act. The decision to abandon one world view for another with very different 95

4 96 implications takes place before those implications have been unpacked in detail. To put some flesh onto the bare bones of my position I want to examine the work of several nineteenth-century scientists, most of whom are associated with philosophical commitments either at the methodological or the world-view level (or both). I shall look at Charles Lyell, Charles Darwin, Richard Owen and Karl Pearson. All except Owen are associated with major theoretical innovations, and Owen himself with a position that, while conservative, was still able to serve as the basis for important conceptual developments. Lyell is my exception that proves the rule his uniformitarian geology arose from his commitment to certain methodological principles, but those principles required him to assume what his contemporaries regarded as a totally implausible steady-state cosmology. All the others engaged in philosophical arguments at the methodological level to defend their positions, and all had world views with substantive philosophical implications. In each case, however, I want to argue that philosophical arguments were either brought in after the basic commitments were made, or played no substantive role in directing the actual research they did. To begin with Lyell: we are all familiar with his defence of uniformitarian geology at the methodological level. Indeed, Lyell s position was that the opposing catastrophist position was unscientific precisely because it encouraged speculation about purely imaginary causes. Recent studies of Lyell have largely agreed that the argument of the Principles of Geology was based on his desire to construct a science of geology that would meet the methodological criteria accepted by the most eminent philosophers of science of the time, especially Sir John Herschel (Secord 1997). But his methodology had important consequences, because he was forced to undermine what Martin Rudwick (1990) calls a developmental world view which would render the methodology unworkable. The claim that a scientist can only appeal to observable causes at observable intensities has two possible implications: either the world exists in a steady state and it is possible for a scientific geology to describe it, or the world changes substantively through time, and (by Lyell s standards) a scientific geology is impossible. Lyell was in effect arguing that a scientific geology must be possible and hence the world must be in a steady state, at least through the whole time span accessible to the geologist. His opponents believed there were good reasons for supposing that the world did change through time, and hence argued that the methodological standards of geological science must be adjusted to take account of this possibility. None of Lyell s contemporaries accepted what they perceived to be his rival world view and Lord Kelvin was eventually able to drive home just why steady-state was incompatible with the physics known at the time.

5 In this case, too close adherence to rigid methodological principles seriously compromised a potentially valuable theory. We know that Lyell s conversion to uniformitarianism took place fairly quickly in the late 1820s. He was raised on a conventional catastrophist/directionalist model of earth history and then, quite suddenly, made a 180-degree turn to steady state. The evidence he studied in France and Italy convinced him of the power of observable causes, but no one else saw this evidence as a sufficient basis for the claim that such causes were all that had operated for as far back was we can hope to see. Why did Lyell switch? In this case I concede that methodological arguments were probably the main driving force: Lyell really did want to create a geology based solely on observable causes. But why was he so determined to rule out even the possibility that those causes had operated with greater intensity in the past? Here there are also world-view considerations. Lyell was not a conventional Christian, and may (like Hutton before him) have wanted to set up a rival to the biblical model of God s relationship to His creation. Equally important, as Michael Bartholomew (1973) showed, Lyell realized that his move toward gradualism was pushing him toward a progressionist evolutionism that would destroy humankind s unique spiritual status, and he saw that the only way out of this trap was to deny progress and hence to eliminate the arrow of time. Lyell s methodological arguments fed into a complex and highly personal set of religious convictions which required him to set up a world view that would allow him to retain his vision of a law-bound universe without threatening his faith in the human spirit. Lyell defended his position largely on methodological grounds, but his contemporaries saw that the methodology was dependent on a world view that none of them were prepared to accept. Charles Darwin was Lyell s greatest disciple, not least because he faced up to exactly those consequences that led Lyell to deny progress. Like Lyell, he was trained within the conventional system, but seems to have converted very suddenly to a completely evolutionary world view in the period just before he began the notebooks which record his moves toward the theory of natural selection (Darwin 1987). We know that the implications of some of his Beagle evidence was being pointed out to him at this time, but (as with Lyell) no one else saw the empirical evidence as a reason for making such a far-reaching break with tradition. Darwin jumped suddenly and wholeheartedly into a world view which accepted all the most radical implications of materialism, including humans as animals, and a model of evolution in which the laws of variation allowed essentially open-ended, unpredictable development. There was never any hint in Darwin s thinking that the universe might be programmed to unfold in regular, predictable lines. Here was a world view full of momentous metaphysical consequences yet the evid- 97

6 98 ence is that Darwin accepted it before he had begun to explore most of those consequences at the philosophical level. This is not to say that Darwin was philosophically naive. Those who used to claim that he was a poor thinker have long been checkmated by confirmation that the Origin of Species was, as his autobiography claimed, one long argument. Yet he was no philosopher as the autobiography also admitted he did not follow abstract chains of reasoning very well and was no metaphysician (Darwin 1958, p. 140). We know that Darwin actively confronted the deeper implications of his theorizing throughout the creative process recorded in his notebooks. Most historians agree, however, that the essential features of the Darwinian world view were already in place in the Zoonomia section of the B Notebook, right at the beginning of the seamless web of theorizing that led to natural selection. They also agree that it took a particularly toughminded kind of personality to press on with a project so much at variance with conventional values (Hodge and Kohn 1985; Browne 1995). My own feeling is that Darwin was someone who dealt with philosophical issues when he had to, not out of choice. He was certainly not ignorant of world view factors in the years leading up to his conversion, and continued to read on a range of topics that raised philosophical issues (in the broader sense of the term), especially concerned with human nature. But this reading included social issues too. Darwin had been raised within the culture of free-enterprise individualism, and even before he read Malthus this may have helped to make him comfortable with a view of nature which stressed individual difference and the unpredictable consequences of letting the interactions between individuals off the leash. This was the kind of habit built so deeply into his thinking that it equates with what Bradley called instinct it was an integral part of Darwin s personality, and it was that personality s gut reaction to the evidence of transmutation that triggered the conversion to so radical a world view. The discovery of natural selection was not a eureka event but setting up the program that led to the discovery was a sudden transformation of world view, so sudden that the philosophical implications had to be left for unpacking alongside the search for a workable mechanism. What about methodology? Here I disagree with Michael Ruse (1979, pp ) who has long maintained that Darwin was deeply influenced by the same methodological concerns as those which drove Lyell. I don t want to deny that Darwin was aware of the debates between Hershel, Whewell and others over the question of what constituted a proper scientific method, or that he wanted to ensure that his work conformed to what was acceptable. Yet even Ruse admits that he did not begin to construct a detailed defence of his approach on these methodological grounds until he re-read Herschel in late 1838, by which time the theory of natural selection had already emerged.

7 Before this, the influence of Lyell was enough to tell him what a theory based on observable causes would look like. Darwin knew from the start what kind of theory he wanted, and only began to check out the philosophical credentials of his approach after he had had his most important idea. My third example is Richard Owen, and here I depend very much on Nicholaas Rupke s account of his work. Traditionally, Owen s vertebrate archetype concept has been seen a product of a Platonic philosophy. Rupke challenges this view, and argues that Owen had no deep philosophical interests or abilities (1993, pp ). The archetype emerged from pragmatic concerns associated with Owen s effort to visualize a unity underlying the diversity of vertebrate form. This was a product of his association with transcendentalism although his early work shows both transcendental and adaptationist interests which, Rupke argues, coexisted without any real synthesis. If anything, the archetype had more affinities with Aristotelian thinking, and Owen switched quite deliberately to a Platonic interpretation in order to avoid the charge of pantheism. In Rupke s account, Owen emerges as someone who used philosophy for his own pragmatic ends, but who made no real effort to develop a philosophically coherent position. Owen was never a pure morphologist who ignored the role of function, but he did have a fundamental commitment at the world-view level which made him hostile to Darwinism. He certainly wanted to stress the underlying unity of diverse adaptive forms, but he was also convinced that the unfolding of form through time, even though leading to adaptive structures, could never be left to so haphazard and unpredictable a process as natural selection. In the end, I suspect, Owen wanted to believe that there were regular laws governing the unpacking of variation. This commitment to the orderliness of form-production is the key characteristic of much anti-darwinism from Owen s time to the present. We see it in St. George Mivart, in the idealist morphologists of the late nineteenth and early twentieth centuries, and in the supporters of orthogenetic evolution through the same period (Bowler 1983). It can also be seen in the work of William Bateson and, significantly, Bateson s ideas still appeal to modern anti-darwinians such as Gerry Webster (1992). These are all people who simply cannot understand how the structure of the world could be produced by trial and error; it just has to be governed by orderly laws of development. Rational argument doesn t come into it, and although many supporters of this position have been philosophical idealists, or believers in a rational Creator, not all of them fit into these categories. My own feeling is that this world view is a real instinct in Bradley s sense. Some personalities just can t bear to think that they are living in a haphazard universe. 99

8 100 My last example from the late nineteenth century is Karl Pearson, the statistician who made major contributions to the Darwinian selection theory. Pearson had strong political views: he was a eugenist (a proponent of selective breeding in the human race). He was also the author of a celebrated work on scientific methodology, the Grammar of Science, which promoted a positivist viewpoint. Commentators on Pearson s work on natural selection have disagreed on whether the underlying motivation was ideological (from the eugenics) or philosophical (from his positivism). But the latest and most detailed work on Pearson by Eileen Magnello (1999) argues that there was no fundamental unity in Pearson s approach to science. He took a purely pragmatic view which allowed him to compartmentalize his work both methodologically and institutionally. His work on evolution bore little relationship to his eugenic studies, and neither can be explained in terms of the philosophy outlined in the Grammar of Science. Here is a scientist known for his contributions to the philosophy of science yet the most detailed biographical study to be made so far suggests that the philosophy was largely irrelevant, representing merely a phase that Pearson went through at a particular point in his career. With the exception of Lyell, the examples I have used suggest a variety of reasons for being suspicious of the claim that philosophical argument played a substantive role in establishing either the world view or the methodology of the scientists discussed. In some cases, scientists did philosophy but ignored it in practical terms (Pearson). In others, there was little genuine interest in philosophy, although philosophical arguments were used to defend positions on pragmatic grounds (Owen and to a lesser extent Darwin). The rapidity of the conversions experienced by Lyell and Darwin suggests that whatever the role of philosophical analysis, personality-driven factors corresponding to the instinct of Bradley s aphorism may have triggered the actual conversions to basic positions. On the model of scientific creativity I am suggesting, rational argument often plays a surprisingly limited role in the decisions that shape the choice of world view or research strategy. If philosophy is called in, it is to defend the resulting positions after they have been constructed on the basis of what the scientists did by instinct or intuition. I conclude with a quotation from Joseph Needham, better-known for his later work on Chinese science but in the 1920s a biologist who was by no means ignorant of philosophy: The fact that the scientific investigator works fifty percent of his time by non-rational means is, it seems, quite insufficiently recognized. There is without the least doubt an instinct for research, and often the most successful investigators of nature are quite unable to give an account of their reasons for doing such and such an experiment or for placing side by side two apparently unrelated facts....and not only by this partial

9 101 replacement of reason by intuition does the work of science go on, but also to the born scientific worker and emphatically they cannot be made the structure of the method of research is as it were given, he cannot explain it to you, though he may be brought to agree a posteriori to a formal logical presentation of the way the method works. (Needham 1928, p. 36) References Bartholomew, M.: 1973, Lyell and Evolution, British Journal of the History of Science 6, Bowler, P.J.: 1983, The Eclipse of Darwinism, Johns Hopkins University Press, Baltimore. Browne, J.: 1995, Charles Darwin: Voyaging, Jonathan Cape, London. Darwin, C.: 1958, Barlow, Nora (ed.), The Autobiography of Charles Darwin, Harcourt Brace, New York. Darwin, C.: 1987, Barrett, P.H. et al. (eds.), Charles Darwin s Theoretical Notebooks, , Cambridge University Press, Cambridge. Hodge, M.J.S. and Kohn, D.: 1985, The Immediate Origins of Natural Selection, in Kohn (ed.), The Darwinian Heritage, Princeton University Press, Princeton, pp Magnello, E.: 1999, The Non-Correlation of Biometrics and Eugenics: Rival Forms of Laboratory Work in Karl Pearson s Career at University College, History of Science 37, 7 106, Needham, J.: 1928, Organicism in Biology, Journal of Philosophical Studies 3, Rudwick, M.J.S.: 1990, Introduction, in Lyell, C. (ed.), Principles of Geology, rep. University of Chicago Press, Chicago. Rupke, N.: 1993, Richard Owen: Victorian Naturalist, Yale University Press, New Haven. Ruse, M.: 1979, The Darwinian Revolution, University of Chicago Press, Chicago. Secord, J.: 1997, Introduction, in Lyell, C. (ed.), Principles of Geology, rep. Penguin, London. Webster, G.: 1992, William Bateson and the Science of Form, in Bateson, W., Materials for the Study of Variation, rep. Johns Hopkins University Press, Baltimore.

10