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Scientific realism: Darwinian smoke and platonic mirrors
Pergamon
Stud. Hist. Phil. Sci., Vol. 21, No. 2, pp. 301-309, 1996 Published by Elsevier Science Ltd. Printed in Great Britain 0039-3681/96 $15.00+0.00
ESSAYREVIEW
Scientific Realism: Darwinian Smoke and Platonic Mirrors Aharon Kantorovich* James Robert Brown, Smoke and Mirrors: How Science Refects Reality (London and New York: Routledge, 1994), 200 pp. ISBN 0 415 09181 0, Paperback U.S.$17.95. About half of the book (Parts I and II) is devoted to the defence of scientific realism (SR) and to rebutting the arguments of some leading anti-realists. Brown complains that the latter (whom he calls ‘enemies of science’) blow ‘smoke’ in our eyes and he undertakes the task of dispersing that smoke. In Part III Brown presents his own realistic view. The general style of the argumentation is refreshing, but occasionally the book produces some smoke of its own. Although the book focusses on the issue of realism, its scope is wider than that; it deals with a broad spectrum of issues from the philosophy and sociology of science. I will concentrate here on the evolutionary criticism of SR and on the attempts to defend Platonic realism. Evolutionary Themes in the Service of Anti-realism
A central argument for SR is that it explains the success of science. Brown refers in particular to Hilary Putnam and J. J. C. Smart as advocates of this view. To spell out the argument: the truth of our theories is the best explanation for their success, therefore they are probably true (granted we accept ‘inference to the best explanation’). However, except for the ‘final’ theory, all actual scientific theories are either false or, if they are true, we cannot know it. But an untrue theory may refer to real entities (without describing correctly their properties or behaviour, for example). Thus, in their attempts to prove the *lo Drezner Street, Tel Aviv, 69497, Israel. 003%3681(95)00@41-0 301
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existence of entities described by successful scientific theories, realists of the above brand try to prove too much. Brown confronts the explanation-of-the-success-of-science view with Bas van Fraassen’s anti-realism based on a Darwinian view of science. Neither Brown nor van Fraassen refers to the above objection. Instead, van Fraassen argues that if competing theories are the analogues of competing species, survival of theories has nothing to do with truth, otherwise we would have to employ a non-Darwinian terminology when we say that theories are progressing towards truth. Therefore, “ ‘truth’ plays no role at all in the success of science” (p. 6).l But this is not a necessary conclusion. A species survives since it reflects more or less faithfully certain aspects of its environment. In other words, some useful information about the environment is encoded in the species’ genotype. So, although Homo sapiens, for example, is not a predetermined goal of evolution, it constitutes progress with respect to the hominid apes which preceded it. The epistemological Darwinist who carries the analogy to a theory which is adapted to its ‘environment’ (consisting of observation data, other theories, etc.), would say that a theory which survives must provide better explanations and predictions, i.e. must be closer to the truth, than its rivals. Nevertheless, in his struggle with van Fraassen’s anti-realism, Brown claims that ‘the Darwinian analogy breaks down since most species could not survive a radical change of environment, the analogue of a novel prediction’ (p. 7). According to this analogy, theories making correct predictions are the analogues of species surviving radical environmental change; the corresponding environmental change in science is presumably caused by the experiments aimed at testing the prediction. Consequently, claims Brown, van Fraassen’s argument for anti-realism fails. However, it seems that it is Brown’s argument which fails. Environmental change is one of the main driving forces of evolution, The great novelties in evolution arise when a species adapts some existing traits to confront radical change in the environment. ‘Blind’ variation is made on forms which have been selected for confronting preexisting environmenal conditions. According to a recent interpretation2 the corresponding great scientific discoveries can be seen as serendipitous discoveries, where a theory which was designed for explaining a given set of phenomena happens to explain a new phenomenon or to make an unexpected prediction. Thus, Brown’s navigation through this maze brings us back to square one; his flawed anti-evolutionary argument against van Fraassen’s flawed evolutionary argument intending to undermine a flawed argument for SR leaves SR undefended still. ‘Indicates page number in the book reviewed. ‘See A. Kantorovich and Y. Ne’eman, ‘Serendipity as a Source of Evolutionary Science’, Studies in History and Philosophyof Science 20 (1989), N-529.
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Brown devotes much space to the evolutionary outlook of cognition and science. In particular, he discusses Michael Ruse’s approach to evolutionary epistemology (EE). He adopts without reservation Ruse’s view that EE as applied to science is incorrect. The main reason for this position is well known: ‘We do not get random variation in new conjectures: theories are highly directed’ (p. 62). But there is an answer to this objection. According to the above-mentioned view of discovery as blind variation, although scientific research is directed, in typical cases significant novelty is generated by serendipity, i.e. when scientists solve unintentionally a problem while trying to solve another. Brown adds another objection of his own to the evolutionary approach as applied to science: ‘the flourishing of astrological and such silly beliefs must be a great embarrassment to any evolutionary epistemologist. In the struggle for survival astrology has proven to be very fit indeed, making it all the way into the U.S. White House’ (p. 62) (referring to the Reagans whom he apparently does not like-to say the least). If we have to take this remark seriously, we may notice that scientific theories compete for survival primarily within the scientific community. Whether or not a certain idea or theory is popular or unpopular in some non-scientific or anti-scientific circles makes little difference to science. Ruse believes only in what he calls ‘Darwinian epistemology’, which holds that the methods of science are determined by our cognitive apparatus which has been selected in the process of biological evolution and became hard-wired in the human genotype. These methods are no more than ‘the usual sort of inductive and deductive rules of inference’ (p. 63). But Ruse does not distinguish between ordinary and scientific experience. It is quite possible that the cognitive structures which guide us successfully in ordinary experience, i.e. in the environment where our cognitive apparatus evolved, are not sufficient for guiding us in the environment created by active experimentation, using technology-intensive devices. And the more are we removed from ordinary conditions, the less suitable is our genetically-based cognitive apparatus for guiding us in doing science.3 Whereas Ruse maintains that the methods of science are geneticallydetermined, Brown goes to the other extreme and tends to believe that there are no ‘biological constraints on human theorizing’ (p. 65). Both positions are implausible. Were Ruse’s position true, it would be difficult to understand why science is so removed from commonsense, why scientific thinking seems sometimes (in modern physics, for example) so unnatural and why the process of science education is so painful for most people. Were Brown’s position true, we would do science without any minimal guidance or restriction and there will be no restrictions on our imagination. This is not the case in science. Although 3For a more detailed argument see A. Kantorovich, Scientific Discovery: Logic and Tinkering (Albany: State University of New York Press, 1993), Chap. 7.
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scientific methods change throughout history, there seems to be a non-changing hard methodological core (which may include rules such as modus ponens, modus tollens or some basic rules of induction and confirmation) which is probably rooted in our genotype. And above all, if science is a continuation of the evolutionary process, nothing is created in V(ECUO. In evolution any new structure evolves from an existing structure and there is some continuation along an evolutionary line. Similarly, in the evolution of science, the existing theoretical structures constrain our imagination. Yet, the new structures are not genetically determined since there are many possible evolutionary paths starting from any given (hard-wired) structure. All depends on chance events. The evolution of science liberates humankind from the tyranny of the genes, yet we are not completely free. Perhaps Brown’s position follows from the fact that he does not believe in the evolution of science. Moreover, in contrast with what Ruse maintains, Brown claims not only that the methods of science are not genetically determined, but also that there are no hard-wired cognitive structures at all. He reasons as follows: ‘organisms, to a very large extent, make the environment they live in. This is certainly true in the purely biological world, and I think it is also true in the realm of epistemology’ (p. 73). From this he concludes that the Darwinian account of cognition is undermined. “Instead of viewing organisms as having a fixed cognitive structure with which they passively grasp the world, we should instead conceive of them as actively imposing their own frameworks upon the world. That is, they try out different ‘paradigms’...“. An implication of this argument is that there is not a ready-made world out there waiting for us to discover it; we create it rather than expose it. This is an anti-realist view which is incompatible with Brown’s generally realist outlook. However, evolutionary epistemologists assume that our cognitive apparatus, through which we grasp the world, was shaped in our natural habitat, the mesocosmos, and became hard-wired in our genotype. Thus, our cognitive apparatus is the onZy ‘paradigm’ through which we grasp the mesocosmos. New paradigms may be ‘tried’ when we face recalcitrant problems which can be solved only by conducting technology-intensive experiments. The new environment exposed to us by these extended sensorimotor organs will be comprehended only within a new conceptual and theoretical framework or a new paradigm. The cognitive structure, whether genetically determined or not, is adapted to the environment. Thus, we have here a possible evolutionary scenario where hard-wired cognitive structures are perfectly compatible both with the active nature of cognition, and with realism. We impose our ‘paradigm’ on the mesocosmos, but this paradigm evolved and was shaped in the mesocosmos, therefore it reflects mesocosmic reality. In general, we impose on the world something that we have learned from it in the course of (organic or scientific) evolution.
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The first ingredient of Brown’s definition of realism is that ‘(t)heories are true or they are false, and what makes them true or false is something which exists completely independently from us’ (p. 81). Brown notes that Putnam rejects the above ingredient of realism: ‘He does not think there is a ready-made world out there that our theories either describe or fail to describe’ (‘p. 83). This position is declared by Brown to be ‘the anti-realism of Putnam’. However, it is compatible with what may be labelled as ‘evolutionary realism’. Every species to a large extent makes its environment. The environment is not ready-made, it is generated as a result of the species’ activity. And so are scientific theories vis-h-vis the world. The world reacts to the questions it is asked. It has a repertoire of different reactions depending on the means of investigations, on the kind of experiments we conduct and on the theories we impose on it. This is far from being anti-realism because different theories reflect different aspects of reality, i.e. of something which is completely independent from us. Wilfred Sellars’ distinction between the manifest image and the scientz@c image parallels our distinction between the hard-wired cognitive apparatus which guides us in the mesocosmos and the extended cognitive apparatus which guides us in the wider environment exposed or created by science. Brown adopts Sellars’ distinction and argues in the following way that there are no constraints on the scientific image (see above). Scientists assume that any ‘part of the physical world... has the same structure as some mathematical object. Since the realm of sets provides all possible mathematical structures, any way that the world could be is exactly isomorphic to some set-theoretic object.’ And since the human mind can grasp set theory and consequently all of these mathematical structures, ‘any way that the physical world could be is also graspable by the human mind... The mere fact that we possess set theory shows that there can be no (non-logical) constraints on our thinking’ (p. 76). Yet, we could come to a diametrically opposed conclusion. Perhaps set-theoretic structures, as well as logic, which are genetically determined, constrain our thinking, so that we can grasp the world only through these structures. The Case for Platonic Realism In Part III Brown focuses on abstract objects and on what he calls ‘a priori’ ways of getting at reality. Concerning these ‘a priori’ ways, he suggests that ‘in very special circumstances we can see the laws of nature-not the regularities, but the abstract patterns themselves’ (p. 99). He claims that ‘some thought experiments allow us to ‘see’ the laws of nature. This abstract realm yields a priori knowledge of the physical world...‘. This kind apriorism ‘is neither certain nor innate. It is not put there by God; it is not recollected; nor is it infallible’ (p. 116). Indeed, as Brown notes, Galileo derived his laws of free fall from thought experiments. Why does Brown call this way of derivation ‘a priori’?
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First, in the thought experiment ‘there have been no new empirical data’. Second, his new theory was not logically deduced from old data, nor was it some kind of logical truth. And third, ‘the transition from Aristotle’s to Galileo’s theory is not just a case of making the simplest overall adjusment to the old theory’ (pp. 114-I 15). But these characteristics are common to other kinds of theory invention, as well. Theory invention which is not a logical derivation may be a result of some chance events, or may be a product of the scientist’s imagination, independently of any empirical data, and only later it is connected to empirical data via testing. Also, in many cases the new theory is not the simplest possible (consider, for example, Copernican cosmology). However, I find the unique contribution of the book to be Brown’s discussion of the ontological status of laws of nature and abstract objects. He starts by exposing the weaknesses in the empiricists’ views which deny the existence of laws of nature. These views are represented by John Earman’s words: ‘the central empiricist intuition is that laws are parasitic on occurent facts’ (p. 91). Against these, Brown tries to defend a ‘Platonic’ view of laws. It should be noted at first that in describing the debate between realists and empiricists, Brown makes no distinction between different kinds of laws of nature. Even if we consider only physical laws we can distinguish between a universal law or theory and a specific law which can be incorporated into, or derived from, a universal theory for a particular case. This distinction is ignored by Hume for obvious reasons, but contemporary philosophers who are familiar with the theories of modern physics may take advantage of it. It may be related to the distinction between ‘accidental’ regularity and law of nature. Whenever a regularity (such as Kepler’s Laws) can be derived from a universal theory (of gravitation) for a specific system (such as the solar system) it can be treated as an instantiation of a law of nature. According to this view, a regularity is a law of nature if it can be embedded in a comprehensive theory which explains the regularity and gives it a wider meaning, or a wider content. This scheme may replace the Ramsey-Lewis empiricist model of laws discussed by Brown (p. 95). According to this model, laws of nature are ‘propositions at the heart of any systematization of the facts of nature’. The ideal systematization should be the simplest and most powerful. This is an empiricist model since laws are still parasitic here on the facts. The difference between this empiricist model and the above view is that in the empiricist model no new content or new meaning is added to the regularity. It just constitutes a deductive reorganization of the facts. Whereas in the above view a wider theoretical significance is attached to the regularity, thus converting it into a law. In his attempt to rebut empiricism and to defend a realist view Brown recruits the example of the ‘standard model’ in particle physics. According to this model the quarks and leptons are arranged in a series of families. ‘The masses of the
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particles grow from family to family in a roughly regular way’ (p. 93). As Brown claims, this classification scheme ‘embodies laws of nature’, such as: ‘the mass of u quark is 5 MeV/c2’. He does not mention another hypothetical law, i.e. a mass formula which will express the pattern of growing masses along the series, and possibly a mass formula within each family. Now, only the first three families are occupied by known particles. Attempts have been made to discover the particles belonging to higher families. But, as Brown notes, the crucial point is that due to the lack of energy and the finiteness of the universe there would be some finite number n such that we could never find or produce, in principle, the particles belonging to the nth family and above. Therefore, the laws about the masses of these higher particles are never instantiated. And the hypothetical mass law, which corresponds to an indefinite number of particles, will be applied only to the finite number of actual and possible particles. Empiricism treats laws as mere regularities, therefore it cannot account for the uninstantiated laws corresponding to the heavier particles. Platonic realism, on the other hand, does account for them. The latter view (advocated mainly by Michael Tooley) is expressed by Brown as follows: ‘laws of nature are relations among universals, i.e. among abstract entities which exist independently of physical objects, independently of us and outside of space and time... Laws on the platonic view are not parasitic on existing objects and events. They have life of their own’ (pp. 96-97). The Platonic nature of laws is indeed demonstrated by the standard model. However, the status of the model is not yet clear. It is not clear whether the series of families is infinite or it is restricted only to the first three families. If indeed these observed regularities-eg. the mass formulae-are not accidental regularities, there should be a deep structure behind them. But such a theory has not been discovered yet. Fortunately, we can find in the history of particle physics much better candidates for demonstrating the Platonic view: the theories of so-called internal symmetries (presumably reflecting some ‘internal structure’ of the particles) which played a central role in particle physics in the sixties. Although the quarks were originated in a theory of internal symmetry, i.e. the SU(3) symmetry scheme, almost nothing was left out of these symmetries. But this does not matter, since no theory is immune from refutation or replacement, and perhaps also current theories will not survive in the long run. The fact that physicists used this unique kind of conception very extensively and quite successfully in their theorizing is what matters. It would therefore be profitable to dwell a bit on the ‘Platonic’ significance of the internal symmetries. An internal symmetry theory yielded classification scheme of hadrons (the strongly interacting particles, which include the baryons and mesons) into ‘families’. The families were dictated by the structure of the underlying symmetry group (they corresponded to the irreducible representations of the
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group). SU(3) had an infinite number of families, out of which only the octet (the ‘eightfold way’) and the decuplet were occupied by observed hadrons. And of course, there were mass formulae in each family. Physicists hoped at first to find a hadron structure and dynamics behind the symmetry group. However, the failure to provide a fully-fledged dynamic theory for the interactions of hadrons and concrete composite models for their internal structure compelled physicists to change their attitude towards the symmetries. Instead of trying to derive the symmetries which govern the classification and interactions of hadrons from concrete models, physicists saw as the object of their study the quantum mechanical operators which measure generalized charges and currents and treated their algebraic relations (i.e. their commutation relations) as the ultimate physical reality. Since they could not anchor their explanation on enduring or stable material objects, they anchored it to the conserved charges such as electric charge, baryon charge and hypercharge or ‘strangeness’. The SU(3) symmetry represented the comptete set of conservation laws not related to space-time, and included also non-additive conserved magnitudes such as total isospin which characterize the isospin multiplet (‘family’) to which a hadron belongs, and the two magnitudes defining the SU(3) supermultiplet (e.g. the octet and decuplet families). As the number of particles became inflated, physicists became primarily interested in the conserved magnitudes and the symmetry. The discovery or production of new hadrons was not an aim in itself. It served the purpose of discovering and confirming theories of symmetry. Such was, for example, the dramatic discovery of the omega-minus particle which strongly confirmed the SU(3) symmetry. The priority of the symmetry over the particles was reflected, therefore, by the fact that the particles were states of a more fundamental entity-the irreducible representation of the internal symmetry group, a symmetry group which was determined by the commutation relations of the observable operators. The symmetry group dictated the hadron spectrum and governed also the dynamics of particle interactions in the sense that it determined (as a generalized conservation law) the possible outcomes of a collision of hadrons. The paiticles
were just transient entities whereas the internal symmetry
seen as the permanent
could be
or ultimate entity. The view which was intuitively held by
some leading physicists in the sixties (such as Werner Heisenberg,4 Murray Gel1 Mann and Yuval Ne’eman) that symmetries stand at the bottom of physical reality, can be comprehended as a ‘Platonic’ view. The ontological status of the internal symmetry can be seen most clearly in cases of hadron production from non-hadronic systems such as two colliding electron-positron beams, where the electron-positron pair just supply their energy to the process in which hadron pairs can be produced. But the 4Heisenberg explicitly referred to Plato in his article: ‘The Nature of Elementary Particles’, Physics Todny 29 (1976), 38.
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energy cannot convert into any arbitrary material system in the process of materialization. The possible outcome is determined by the conservation laws or the symmetry. Thus, the ontological priority of the symmetry can be illusrated by the following ‘thought experiment’. In the hypothetical world with zero baryon number there can be moments when the world is free of hadron matter (when all baryons are annihilated and all mesons decay) and there remain only photons and leptons. In such a hadron-free world, hadrons can be created in photon-photon or electron-positron collisions. But the symmetry dictates what possible hadrons will be produced. Thus, in this physically possible world there are situations where the symmetry exists while hadrons do not. This picture entirely accords with the version of Platonism formulated by Brown. We have here a physically possible world stripped of hadron matter. In this world, abstract entities, such as conservation laws and symmetries, ‘exist independently of physical objects, independently of us and outside space and time’, to use Brown’s words. And further, the conservation laws and symmetries ‘are not parasitic on existing objects and events. They have life of their own’. This physically possible world is totally incompatible with the central empiricist intuition (as expressed by Earman’s words) ‘that laws are parasitic on occurent facts’.
Stud. Hist. Phil. Sci., Vol. 21, No. 2, pp. 301-309, 1996 Published by Elsevier Science Ltd. Printed in Great Britain 0039-3681/96 $15.00+0.00
ESSAYREVIEW
Scientific Realism: Darwinian Smoke and Platonic Mirrors Aharon Kantorovich* James Robert Brown, Smoke and Mirrors: How Science Refects Reality (London and New York: Routledge, 1994), 200 pp. ISBN 0 415 09181 0, Paperback U.S.$17.95. About half of the book (Parts I and II) is devoted to the defence of scientific realism (SR) and to rebutting the arguments of some leading anti-realists. Brown complains that the latter (whom he calls ‘enemies of science’) blow ‘smoke’ in our eyes and he undertakes the task of dispersing that smoke. In Part III Brown presents his own realistic view. The general style of the argumentation is refreshing, but occasionally the book produces some smoke of its own. Although the book focusses on the issue of realism, its scope is wider than that; it deals with a broad spectrum of issues from the philosophy and sociology of science. I will concentrate here on the evolutionary criticism of SR and on the attempts to defend Platonic realism. Evolutionary Themes in the Service of Anti-realism
A central argument for SR is that it explains the success of science. Brown refers in particular to Hilary Putnam and J. J. C. Smart as advocates of this view. To spell out the argument: the truth of our theories is the best explanation for their success, therefore they are probably true (granted we accept ‘inference to the best explanation’). However, except for the ‘final’ theory, all actual scientific theories are either false or, if they are true, we cannot know it. But an untrue theory may refer to real entities (without describing correctly their properties or behaviour, for example). Thus, in their attempts to prove the *lo Drezner Street, Tel Aviv, 69497, Israel. 003%3681(95)00@41-0 301
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existence of entities described by successful scientific theories, realists of the above brand try to prove too much. Brown confronts the explanation-of-the-success-of-science view with Bas van Fraassen’s anti-realism based on a Darwinian view of science. Neither Brown nor van Fraassen refers to the above objection. Instead, van Fraassen argues that if competing theories are the analogues of competing species, survival of theories has nothing to do with truth, otherwise we would have to employ a non-Darwinian terminology when we say that theories are progressing towards truth. Therefore, “ ‘truth’ plays no role at all in the success of science” (p. 6).l But this is not a necessary conclusion. A species survives since it reflects more or less faithfully certain aspects of its environment. In other words, some useful information about the environment is encoded in the species’ genotype. So, although Homo sapiens, for example, is not a predetermined goal of evolution, it constitutes progress with respect to the hominid apes which preceded it. The epistemological Darwinist who carries the analogy to a theory which is adapted to its ‘environment’ (consisting of observation data, other theories, etc.), would say that a theory which survives must provide better explanations and predictions, i.e. must be closer to the truth, than its rivals. Nevertheless, in his struggle with van Fraassen’s anti-realism, Brown claims that ‘the Darwinian analogy breaks down since most species could not survive a radical change of environment, the analogue of a novel prediction’ (p. 7). According to this analogy, theories making correct predictions are the analogues of species surviving radical environmental change; the corresponding environmental change in science is presumably caused by the experiments aimed at testing the prediction. Consequently, claims Brown, van Fraassen’s argument for anti-realism fails. However, it seems that it is Brown’s argument which fails. Environmental change is one of the main driving forces of evolution, The great novelties in evolution arise when a species adapts some existing traits to confront radical change in the environment. ‘Blind’ variation is made on forms which have been selected for confronting preexisting environmenal conditions. According to a recent interpretation2 the corresponding great scientific discoveries can be seen as serendipitous discoveries, where a theory which was designed for explaining a given set of phenomena happens to explain a new phenomenon or to make an unexpected prediction. Thus, Brown’s navigation through this maze brings us back to square one; his flawed anti-evolutionary argument against van Fraassen’s flawed evolutionary argument intending to undermine a flawed argument for SR leaves SR undefended still. ‘Indicates page number in the book reviewed. ‘See A. Kantorovich and Y. Ne’eman, ‘Serendipity as a Source of Evolutionary Science’, Studies in History and Philosophyof Science 20 (1989), N-529.
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Brown devotes much space to the evolutionary outlook of cognition and science. In particular, he discusses Michael Ruse’s approach to evolutionary epistemology (EE). He adopts without reservation Ruse’s view that EE as applied to science is incorrect. The main reason for this position is well known: ‘We do not get random variation in new conjectures: theories are highly directed’ (p. 62). But there is an answer to this objection. According to the above-mentioned view of discovery as blind variation, although scientific research is directed, in typical cases significant novelty is generated by serendipity, i.e. when scientists solve unintentionally a problem while trying to solve another. Brown adds another objection of his own to the evolutionary approach as applied to science: ‘the flourishing of astrological and such silly beliefs must be a great embarrassment to any evolutionary epistemologist. In the struggle for survival astrology has proven to be very fit indeed, making it all the way into the U.S. White House’ (p. 62) (referring to the Reagans whom he apparently does not like-to say the least). If we have to take this remark seriously, we may notice that scientific theories compete for survival primarily within the scientific community. Whether or not a certain idea or theory is popular or unpopular in some non-scientific or anti-scientific circles makes little difference to science. Ruse believes only in what he calls ‘Darwinian epistemology’, which holds that the methods of science are determined by our cognitive apparatus which has been selected in the process of biological evolution and became hard-wired in the human genotype. These methods are no more than ‘the usual sort of inductive and deductive rules of inference’ (p. 63). But Ruse does not distinguish between ordinary and scientific experience. It is quite possible that the cognitive structures which guide us successfully in ordinary experience, i.e. in the environment where our cognitive apparatus evolved, are not sufficient for guiding us in the environment created by active experimentation, using technology-intensive devices. And the more are we removed from ordinary conditions, the less suitable is our genetically-based cognitive apparatus for guiding us in doing science.3 Whereas Ruse maintains that the methods of science are geneticallydetermined, Brown goes to the other extreme and tends to believe that there are no ‘biological constraints on human theorizing’ (p. 65). Both positions are implausible. Were Ruse’s position true, it would be difficult to understand why science is so removed from commonsense, why scientific thinking seems sometimes (in modern physics, for example) so unnatural and why the process of science education is so painful for most people. Were Brown’s position true, we would do science without any minimal guidance or restriction and there will be no restrictions on our imagination. This is not the case in science. Although 3For a more detailed argument see A. Kantorovich, Scientific Discovery: Logic and Tinkering (Albany: State University of New York Press, 1993), Chap. 7.
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scientific methods change throughout history, there seems to be a non-changing hard methodological core (which may include rules such as modus ponens, modus tollens or some basic rules of induction and confirmation) which is probably rooted in our genotype. And above all, if science is a continuation of the evolutionary process, nothing is created in V(ECUO. In evolution any new structure evolves from an existing structure and there is some continuation along an evolutionary line. Similarly, in the evolution of science, the existing theoretical structures constrain our imagination. Yet, the new structures are not genetically determined since there are many possible evolutionary paths starting from any given (hard-wired) structure. All depends on chance events. The evolution of science liberates humankind from the tyranny of the genes, yet we are not completely free. Perhaps Brown’s position follows from the fact that he does not believe in the evolution of science. Moreover, in contrast with what Ruse maintains, Brown claims not only that the methods of science are not genetically determined, but also that there are no hard-wired cognitive structures at all. He reasons as follows: ‘organisms, to a very large extent, make the environment they live in. This is certainly true in the purely biological world, and I think it is also true in the realm of epistemology’ (p. 73). From this he concludes that the Darwinian account of cognition is undermined. “Instead of viewing organisms as having a fixed cognitive structure with which they passively grasp the world, we should instead conceive of them as actively imposing their own frameworks upon the world. That is, they try out different ‘paradigms’...“. An implication of this argument is that there is not a ready-made world out there waiting for us to discover it; we create it rather than expose it. This is an anti-realist view which is incompatible with Brown’s generally realist outlook. However, evolutionary epistemologists assume that our cognitive apparatus, through which we grasp the world, was shaped in our natural habitat, the mesocosmos, and became hard-wired in our genotype. Thus, our cognitive apparatus is the onZy ‘paradigm’ through which we grasp the mesocosmos. New paradigms may be ‘tried’ when we face recalcitrant problems which can be solved only by conducting technology-intensive experiments. The new environment exposed to us by these extended sensorimotor organs will be comprehended only within a new conceptual and theoretical framework or a new paradigm. The cognitive structure, whether genetically determined or not, is adapted to the environment. Thus, we have here a possible evolutionary scenario where hard-wired cognitive structures are perfectly compatible both with the active nature of cognition, and with realism. We impose our ‘paradigm’ on the mesocosmos, but this paradigm evolved and was shaped in the mesocosmos, therefore it reflects mesocosmic reality. In general, we impose on the world something that we have learned from it in the course of (organic or scientific) evolution.
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The first ingredient of Brown’s definition of realism is that ‘(t)heories are true or they are false, and what makes them true or false is something which exists completely independently from us’ (p. 81). Brown notes that Putnam rejects the above ingredient of realism: ‘He does not think there is a ready-made world out there that our theories either describe or fail to describe’ (‘p. 83). This position is declared by Brown to be ‘the anti-realism of Putnam’. However, it is compatible with what may be labelled as ‘evolutionary realism’. Every species to a large extent makes its environment. The environment is not ready-made, it is generated as a result of the species’ activity. And so are scientific theories vis-h-vis the world. The world reacts to the questions it is asked. It has a repertoire of different reactions depending on the means of investigations, on the kind of experiments we conduct and on the theories we impose on it. This is far from being anti-realism because different theories reflect different aspects of reality, i.e. of something which is completely independent from us. Wilfred Sellars’ distinction between the manifest image and the scientz@c image parallels our distinction between the hard-wired cognitive apparatus which guides us in the mesocosmos and the extended cognitive apparatus which guides us in the wider environment exposed or created by science. Brown adopts Sellars’ distinction and argues in the following way that there are no constraints on the scientific image (see above). Scientists assume that any ‘part of the physical world... has the same structure as some mathematical object. Since the realm of sets provides all possible mathematical structures, any way that the world could be is exactly isomorphic to some set-theoretic object.’ And since the human mind can grasp set theory and consequently all of these mathematical structures, ‘any way that the physical world could be is also graspable by the human mind... The mere fact that we possess set theory shows that there can be no (non-logical) constraints on our thinking’ (p. 76). Yet, we could come to a diametrically opposed conclusion. Perhaps set-theoretic structures, as well as logic, which are genetically determined, constrain our thinking, so that we can grasp the world only through these structures. The Case for Platonic Realism In Part III Brown focuses on abstract objects and on what he calls ‘a priori’ ways of getting at reality. Concerning these ‘a priori’ ways, he suggests that ‘in very special circumstances we can see the laws of nature-not the regularities, but the abstract patterns themselves’ (p. 99). He claims that ‘some thought experiments allow us to ‘see’ the laws of nature. This abstract realm yields a priori knowledge of the physical world...‘. This kind apriorism ‘is neither certain nor innate. It is not put there by God; it is not recollected; nor is it infallible’ (p. 116). Indeed, as Brown notes, Galileo derived his laws of free fall from thought experiments. Why does Brown call this way of derivation ‘a priori’?
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First, in the thought experiment ‘there have been no new empirical data’. Second, his new theory was not logically deduced from old data, nor was it some kind of logical truth. And third, ‘the transition from Aristotle’s to Galileo’s theory is not just a case of making the simplest overall adjusment to the old theory’ (pp. 114-I 15). But these characteristics are common to other kinds of theory invention, as well. Theory invention which is not a logical derivation may be a result of some chance events, or may be a product of the scientist’s imagination, independently of any empirical data, and only later it is connected to empirical data via testing. Also, in many cases the new theory is not the simplest possible (consider, for example, Copernican cosmology). However, I find the unique contribution of the book to be Brown’s discussion of the ontological status of laws of nature and abstract objects. He starts by exposing the weaknesses in the empiricists’ views which deny the existence of laws of nature. These views are represented by John Earman’s words: ‘the central empiricist intuition is that laws are parasitic on occurent facts’ (p. 91). Against these, Brown tries to defend a ‘Platonic’ view of laws. It should be noted at first that in describing the debate between realists and empiricists, Brown makes no distinction between different kinds of laws of nature. Even if we consider only physical laws we can distinguish between a universal law or theory and a specific law which can be incorporated into, or derived from, a universal theory for a particular case. This distinction is ignored by Hume for obvious reasons, but contemporary philosophers who are familiar with the theories of modern physics may take advantage of it. It may be related to the distinction between ‘accidental’ regularity and law of nature. Whenever a regularity (such as Kepler’s Laws) can be derived from a universal theory (of gravitation) for a specific system (such as the solar system) it can be treated as an instantiation of a law of nature. According to this view, a regularity is a law of nature if it can be embedded in a comprehensive theory which explains the regularity and gives it a wider meaning, or a wider content. This scheme may replace the Ramsey-Lewis empiricist model of laws discussed by Brown (p. 95). According to this model, laws of nature are ‘propositions at the heart of any systematization of the facts of nature’. The ideal systematization should be the simplest and most powerful. This is an empiricist model since laws are still parasitic here on the facts. The difference between this empiricist model and the above view is that in the empiricist model no new content or new meaning is added to the regularity. It just constitutes a deductive reorganization of the facts. Whereas in the above view a wider theoretical significance is attached to the regularity, thus converting it into a law. In his attempt to rebut empiricism and to defend a realist view Brown recruits the example of the ‘standard model’ in particle physics. According to this model the quarks and leptons are arranged in a series of families. ‘The masses of the
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particles grow from family to family in a roughly regular way’ (p. 93). As Brown claims, this classification scheme ‘embodies laws of nature’, such as: ‘the mass of u quark is 5 MeV/c2’. He does not mention another hypothetical law, i.e. a mass formula which will express the pattern of growing masses along the series, and possibly a mass formula within each family. Now, only the first three families are occupied by known particles. Attempts have been made to discover the particles belonging to higher families. But, as Brown notes, the crucial point is that due to the lack of energy and the finiteness of the universe there would be some finite number n such that we could never find or produce, in principle, the particles belonging to the nth family and above. Therefore, the laws about the masses of these higher particles are never instantiated. And the hypothetical mass law, which corresponds to an indefinite number of particles, will be applied only to the finite number of actual and possible particles. Empiricism treats laws as mere regularities, therefore it cannot account for the uninstantiated laws corresponding to the heavier particles. Platonic realism, on the other hand, does account for them. The latter view (advocated mainly by Michael Tooley) is expressed by Brown as follows: ‘laws of nature are relations among universals, i.e. among abstract entities which exist independently of physical objects, independently of us and outside of space and time... Laws on the platonic view are not parasitic on existing objects and events. They have life of their own’ (pp. 96-97). The Platonic nature of laws is indeed demonstrated by the standard model. However, the status of the model is not yet clear. It is not clear whether the series of families is infinite or it is restricted only to the first three families. If indeed these observed regularities-eg. the mass formulae-are not accidental regularities, there should be a deep structure behind them. But such a theory has not been discovered yet. Fortunately, we can find in the history of particle physics much better candidates for demonstrating the Platonic view: the theories of so-called internal symmetries (presumably reflecting some ‘internal structure’ of the particles) which played a central role in particle physics in the sixties. Although the quarks were originated in a theory of internal symmetry, i.e. the SU(3) symmetry scheme, almost nothing was left out of these symmetries. But this does not matter, since no theory is immune from refutation or replacement, and perhaps also current theories will not survive in the long run. The fact that physicists used this unique kind of conception very extensively and quite successfully in their theorizing is what matters. It would therefore be profitable to dwell a bit on the ‘Platonic’ significance of the internal symmetries. An internal symmetry theory yielded classification scheme of hadrons (the strongly interacting particles, which include the baryons and mesons) into ‘families’. The families were dictated by the structure of the underlying symmetry group (they corresponded to the irreducible representations of the
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group). SU(3) had an infinite number of families, out of which only the octet (the ‘eightfold way’) and the decuplet were occupied by observed hadrons. And of course, there were mass formulae in each family. Physicists hoped at first to find a hadron structure and dynamics behind the symmetry group. However, the failure to provide a fully-fledged dynamic theory for the interactions of hadrons and concrete composite models for their internal structure compelled physicists to change their attitude towards the symmetries. Instead of trying to derive the symmetries which govern the classification and interactions of hadrons from concrete models, physicists saw as the object of their study the quantum mechanical operators which measure generalized charges and currents and treated their algebraic relations (i.e. their commutation relations) as the ultimate physical reality. Since they could not anchor their explanation on enduring or stable material objects, they anchored it to the conserved charges such as electric charge, baryon charge and hypercharge or ‘strangeness’. The SU(3) symmetry represented the comptete set of conservation laws not related to space-time, and included also non-additive conserved magnitudes such as total isospin which characterize the isospin multiplet (‘family’) to which a hadron belongs, and the two magnitudes defining the SU(3) supermultiplet (e.g. the octet and decuplet families). As the number of particles became inflated, physicists became primarily interested in the conserved magnitudes and the symmetry. The discovery or production of new hadrons was not an aim in itself. It served the purpose of discovering and confirming theories of symmetry. Such was, for example, the dramatic discovery of the omega-minus particle which strongly confirmed the SU(3) symmetry. The priority of the symmetry over the particles was reflected, therefore, by the fact that the particles were states of a more fundamental entity-the irreducible representation of the internal symmetry group, a symmetry group which was determined by the commutation relations of the observable operators. The symmetry group dictated the hadron spectrum and governed also the dynamics of particle interactions in the sense that it determined (as a generalized conservation law) the possible outcomes of a collision of hadrons. The paiticles
were just transient entities whereas the internal symmetry
seen as the permanent
could be
or ultimate entity. The view which was intuitively held by
some leading physicists in the sixties (such as Werner Heisenberg,4 Murray Gel1 Mann and Yuval Ne’eman) that symmetries stand at the bottom of physical reality, can be comprehended as a ‘Platonic’ view. The ontological status of the internal symmetry can be seen most clearly in cases of hadron production from non-hadronic systems such as two colliding electron-positron beams, where the electron-positron pair just supply their energy to the process in which hadron pairs can be produced. But the 4Heisenberg explicitly referred to Plato in his article: ‘The Nature of Elementary Particles’, Physics Todny 29 (1976), 38.
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energy cannot convert into any arbitrary material system in the process of materialization. The possible outcome is determined by the conservation laws or the symmetry. Thus, the ontological priority of the symmetry can be illusrated by the following ‘thought experiment’. In the hypothetical world with zero baryon number there can be moments when the world is free of hadron matter (when all baryons are annihilated and all mesons decay) and there remain only photons and leptons. In such a hadron-free world, hadrons can be created in photon-photon or electron-positron collisions. But the symmetry dictates what possible hadrons will be produced. Thus, in this physically possible world there are situations where the symmetry exists while hadrons do not. This picture entirely accords with the version of Platonism formulated by Brown. We have here a physically possible world stripped of hadron matter. In this world, abstract entities, such as conservation laws and symmetries, ‘exist independently of physical objects, independently of us and outside space and time’, to use Brown’s words. And further, the conservation laws and symmetries ‘are not parasitic on existing objects and events. They have life of their own’. This physically possible world is totally incompatible with the central empiricist intuition (as expressed by Earman’s words) ‘that laws are parasitic on occurent facts’.