Biology (Philosophy of) in the nineteenth century
- Philosophy of biology in the nineteenth century Jagdish Hattiangadi THE PHILOSOPHY OF BIOLOGY The emergence of biology as a unified subject Students of history and of biology share a common delight: as they study the details of any subject, they find a fascinating diversity of cases which far exceeds any preconceived expectations. But that is not their sole delight. Some will also see unifying themes therein, with coincidences that beg for explanation and leitmotifs which please the aesthete. Some scholars choose to stress the diversity, perhaps even the perversity, to be found in events in history (or, in biology, of living forms). Other scholars may feel happier following the motto e pluribus unum. There is no right or wrong to it, that one is a unifier and another a divider of forms. We ascribe these differences in scientific or philosophical temperament to individual style or taste: some like a tidy story and others prefer a wealth of detail. Nor is this a matter of respect or lack of it for detailed facts. A grand unifier may study facts painstakingly while trying to unify (perhaps bending the facts, or perhaps ruefully admitting failure) while the person with a predilection for detail may believe in it only in principle, leaving it to others to dig them up and record them. Those who grant that details are important may do so either to prove that they fit into a grand scheme or to disprove that very point. This difference is, perhaps not unsurprisingly, more than a matter of style. It is also an issue of substance in the nineteenth century, both in history and in biology. It became a topical question whether there is meaning in unfolding events: whether history exhibits fundamental laws, and whether there is a grand design to explain adaptation among living things. Do some things just happen, or is everything determined by a deep plan? Philosophers and scientists alike were on both sides of this celebrated debate, and on each side there are examples of intellectuals of both temperaments. But the issue of substance was not merely a matter of temperament, it was a matter of doctrine, of theory and of the future direction of thought. The main issue of substance which animates the philosophy of biology in the nineteenth century has its root in the seventeenth, in the difficulties faced by Galileo’s mechanical conception of the universe. This conception of a world ruled by mathematical laws of motion, or mechanics, became the central feature of the so-called scientific revolution of the seventeenth century. It was proposed by Galileo consciously in opposition to the Scholastic conception of the universe, which was dismissed with Ptolemaic astronomy as false. Galileo proposed that it was superseded by the new Copernican solar system, and proposed his new mechanics to replace the older physics of the scholastics. The subsequent success of the mechanical conception of the universe cannot be equated with the success of any one of the mechanical systems proposed to describe motion. Galileo’s laws were followed in turn by those of Descartes, Huygens, Newton, d’Alembert, Euler, Lagrange, Poisson, Laplace, Fresnel, Hamilton, Maxwell. At the end of the period we are studying there followed entirely new mechanical systems from Einstein (relativistic laws of motion) and Schrödinger and others (quantum mechanics). The accepted laws of motion keep changing, sometimes in matters of detail and at others in more fundamental ways, but the general idea of a mechanical universe conjoins consistently with any of them. What is common to all the mechanical conceptions of the universe following Galileo is what they seemed to exclude: certain aspects of the universe which were readily understood as far back as in Aristotle’s or even in Plato’s accounts of the world seemed to be incomprehensible within a thoroughgoing mechanistic scheme. The existence of forms, the prevalence of purposes and the realm of morality seemed to lie entirely beyond the mechanical conception of the universe. If we regard mechanics as forming the basis of a new comprehensive philosophy to rival the old Scholastic philosophies (as modified from those of Plato and Aristotle), then form, purpose and morality had to be understood somehow as part of the new mechanical conception. But how? There is no ready explanation for the existence of any of these three. To resolve this difficulty there were two basic ways to proceed: with ingenuity we could develop mechanical models to reproduce the effect of forms, purposes and morality artificially; or we could devise a conception of the world in which form, purpose and morality are quite real, and wherein mechanics has a diminished role to play in our understanding. A thoroughgoing mechanist could dismiss forms as residing in the eye of the beholder, or (invoking the medieval doctrine of nominalism) as residing in the act of naming. Purposes could be denied to all animals, and restricted to the human psyche, within which can also be located the free will, allowing us the luxury as moral beings, apparently denied to animals, of being naughty (domesticated animals being interesting exceptions). In this convoluted way the problems posed by forms, by purposes and by morality can be reduced to the mystery of the human mind. But having done so, we have only artificially isolated the recalcitrant Scholastic phenomena without having thus made any attempt at solving the problems posed for mechanists. The thoroughgoing mechanist such as Descartes who throws all recalcitrant Scholastic phenomena into the category of mind is no better off as a mechanist than the one who, like La Mettrie, regards all these phenomena as external, and explicable in material terms, without saying exactly how. Interaction between two substances is ruled out by Spinoza’s powerful argument that a substance is by definition autonomous, and hence cannot be affected by anything which is independent of it. The mechanical conception of the universe seemed to leave us with no option but to adopt one of these two alternatives: some form of materialism, or some form of idealism; we have either to seek an extension of mechanism to model and recreate the effect of the recalcitrant Scholastic phenomena or to subsume all material phenomena under the realm of ideas in a modified form. A titanic debate was touched off between Newton and Leibniz just prior to the latter’s death, which is found recorded in the Leibniz-Clarke correspondence [10.1]. Clarke, as Newton’s voice, describes a material world which is governed by mathematical laws, but which has many physical features for which there are no mathematical laws governing them. Newton’s own view was that God acted upon the world from time to time to preserve it in its required form (the solar system, for instance, was unstable according to Newton, and continues without signs of collapse because God holds the planets constantly within their orbits). Leibniz, on the other hand, proposed a fully rationalist conception of the universe, in which everything and every event is determined by the Principle of Sufficient Reason. The world according to Leibniz consists of a community of spirits (monads) each of which is completely determined in itself by its own nature. Each interacts successfully with other monads (or appears to do so, since any monad’s experiences of other monads are completely predetermined by its own nature) only because of the pre-established harmony by which God has established an order among all things (monads). If we neglect the references to God, either because we no longer believe in any, or for those who still continue to do so because we want to restrict ourselves to natural phenomena, then the choice for us lies between these two schemes: Firstly, a world in which some things just exist and some events just happen without natural cause, and they have no natural explanation (Newton). Secondly, a world which is fully determined in its smallest detail, and in which everything and every event within it is determined by a Grand Design which pre-establishes an otherwise inexplicable harmony (Leibniz). These two points of view—one materialist and the other idealist, one indeterministic and the other deterministic, one antithetical to Scholasticism and the other friendly to some of its features, one seeking to understand what can be understood only in terms of the laws of matter and motion, and the other seeking to understand everything in terms of a pre-established rational order—are not the only two possible ways to approach the subject. But they did seem to many to offer the two most reasonable alternatives. In biology in the nineteenth century, however, are to be found some new ideas which cut across these extremes. They resolved some of the difficulties which were raised within Galileo’s mechanical conception of the universe. Thoroughgoing mechanists who avoided the relegation of all recalcitrant Scholastic phenomena to the mind, but accepted instead that forms and purposes were to be found among the phenomena (in short, materialists), had to find a way to understand form, purpose and morality in a material world governed by mechanical laws. A lively discussion between materialists and their opponents characterizes what we may identify in retrospect as the condition of biology as it coalesced into a subject in the nineteenth century. Biology or the science of life arose as a unified subject among the discussions between French materialists and their opponents in the last years of the eighteenth century. Buffon, La Mettrie, Lamarck and their free-thinking contemporaries conceived a unified science of life, or of biology. Such was the need for recognizing this new subject that it was quickly taken up by many scholars of different persuasion across the scientific world. There is no doubt of course that the unity of biology was strengthened by the remarkable but later developments in cytology, genetics and evolutionary theory all of which cut across earlier divisions within the previously known sciences of living things. The prior unification of the sciences of life depends on this: form and purpose are to be found among all living things on earth, and barely outside of them. The need for a unified science of life arises out of the need to find mechanical models for these two categories of recalcitrant Scholastic phenomena, all of which seem to be found in and about living things. These issues are central to ‘Modern Philosophy’ as this is taught in universities to this day. If we take that as our cue, we may say confidently that the unification of biology was a philosophical attempt to solve some central problems of modern philosophy. On mechanism and vitalism The schism in modern thought between the thoroughgoing mechanists and those who sought to put mechanism in its proper (and diminished) place in the grand idealist scheme begins with the clash between Newton and Leibniz. Unlike the seventeenth century, the eighteenth marks a deepening separation between natural philosophy and moral philosophy. By the nineteenth century this division became established. The word ‘philosopher’ came to be reserved for an apologist for idealism or perhaps an opponent of thoroughgoing mechanism in any form, and the expression ‘scientist’ came into use for the thoroughgoing mechanist who followed the experimental method of investigation. These two professions came to inhabit different parts of the university, and came to adopt different curricula, and thus and only so were able to keep the peace. The mechanists adhered to three things: some form of the laws of motion to understand everything in the world; a conception of scientific method as experimental and inductive; and a healthy scepticism about Scholastic issues which were dismissed as superstitious. It is an unfortunate fact that heated debates between scientists on the question of how to accommodate form and purpose within mechanism often led them to accuse one another of becoming unscientific. Two schools of thought exist within the group of thoroughgoing mechanists early in the nineteenth century concerning how to accommodate purpose in nature. One group sought to explain it by a special life force (attached to a kind of fluid, vital matter); another group hoped to explain it entirely in terms of other known forms of matter and force, such as the magnetic, the electric, the chemical, etc. The first sought to identify all living forms by an ingredient common to them, and the other sought to understand life in terms of organization (of the organism) from ordinary or inert matter. In principle either of these ploys might have been true (or of course neither might be true). As it happens, by the end of the nineteenth century the odds had swung in favour of the latter point of view, and in the twentieth century, whatever a scientist accepts she will regard vitalism as an intellectual oddity. Nevertheless, in the nineteenth century it would be premature to describe vitalism as unscientific as is done all too often today. One of the unfortunate terminological ambiguities of this debate lies in the description of the opponents of vitalism as ‘mechanists’. In a certain sense, a vitalist is also a mechanist who happens to believe in an additional element with a force much like magnetic or electric forces as they were conceived at the end of the eighteenth century. The mechanists were, therefore, not necessarily the only mechanists in that conflict of opinion, if by mechanics we mean the well known laws of motion accepted at the time as governing all matter. Galvani’s experimental and theoretical contributions were regarded as unscientific by Volta late in the eighteenth century, but we may wish to differ in our assessment today. Perhaps Galvani was not correct in arguing that since the severed leg of a frog had been separated from its organisation (i.e. within the previously live frog) its twitching when probed by two metal prongs shows that there resides in the severed limb of the frog the principle of living matter. Perhaps Volta was right that this was not even a credible argument. But if it had not been for Galvani’s argument, would Volta have sought to show that the twitch in the severed leg of a frog arose from the ordinary metals separated by the ordinary acidic fluid therein? Would he have otherwise looked for an apparatus to duplicate his model of a schematic form of a frog’s leg being probed by two metal prongs, by inventing the voltaic pile? And would we have discovered current electricity, or the decomposition of water by electrolysis, or any of those remarkable things in physics and chemistry which followed Volta’s invention of the pile and the discovery of the electric current? Moreover, the methods used by vitalists could be and often were thoroughly experimental. Bichat made an excellent case for vitalism by conducting detailed studies of anatomical phenomena. Perhaps it is this more than anything else which led Claude Bernard, the great physiologist and methodologist, to recognize some fifty years later that while the experimental method needs preconceived ideas, it needs also a healthy scepticism (see pp. 292–5 below). Between the time of Bichat and Bernard, the tide seem to have swung against vitalism in physiology, though the full demise of vitalism had to await the twentieth century. The debate between vitalists and mechanists is a fine example of a thoroughly scientific controversy, in which experimental results and good arguments played an important role in the eventual outcome. As the difficulties for vitalism mounted and those for mechanists diminished, the tide of opinion swung against the vitalists. It is frequently but not invariably true that predominance of opinion among experts is a good gauge of the strength of the case made for and against the opinion, and in this instance the correlation seems to be quite good. The factors which led to the decline of vitalism in the nineteenth century lay both within and without biology. In physics, there was an eighteenth-century consensus that the various forces of nature were distinct, and that each of them emanated from a characteristic and dis-tinct type of matter. For example, physicists thought they had discovered electric fluids which supported electric forces, and magnetic fluids which supported magnetic forces, and caloric, which induced heat. This is quite compatible with a living material supporting a life force. But in the nineteenth century the growing experimental confirmation of the interchangeability of forces (or the unity of all force, later redefined and identified as ‘energy’) came to undermine the vitalist idea of a special force shared by all and only living things. Within biology, arguments leading to the demise of mechanism had much to do with the rise and predominance of physiology as opposed to anatomy in the study of form. The close connection between physiological function and evolution in Darwin’s account eventually made vitalism an outsider to science as Darwin’s views, and their improved descendants, came to occupy centre stage in biology. Although vitalism had its share of friends and opponents in the nineteenth century, it was only after Darwin’s conception of evolution by natural selection was grasped that vitalism came to fall in favour very generally. The heated debate over the merits of Darwin’s theory of evolution by natural selection, however, was not between two versions of mechanism as was the case between the vitalists and the so-called mechanists. The issue debated by Darwin was the very different one philosophers had raised as the problem of design. He provided us with a mechanistic alternative to a grand design, or a pre-established harmony, or to some form of idealism. If we regard the French materialists’ location of forms and purposes in matter as basically correct (in contradistinction to interactionists who find them in the mind), then we may say that Darwin’s theory of evolution by natural selection solves the mind-matter problem (or the mind-body problem) of the Cartesian philosopher. On biology as a development of the science of Galileo When Leibniz proposed his idea of a divinely pre-established harmony, he had in mind the extraordinary coincidence that two monads which ‘interact’ have complementary experiences. In his account, two monads have two aspects of the same world. Each monad determines its own inner nature, and two ‘interacting’ monads might well have not been co-ordinated, and thus they may fail to ‘interact’ at all. (They may not possess aspects of the same world.) But in creating the universe, God created the best of all possible universes, and thus created a universe in which everything which exists and every event within each monad is there for a reason: were anything other than as it is, this would have been a different possible universe and therefore a universe inferior to this one. This being the best of all possible universes it determines for us what there is in every minutest detail—a determinism as complete as can be imagined—based on the assumption that anything else would not have sufficient reason to exist. It is a remarkable fact of the history of ideas that Leibniz, the author of modern determinism (i.e. the Law of Sufficient Reason), was forgotten as its true author by the early part of the nineteenth century. Instead, the determinism invented by Leibniz is attributed to Newtonian mechanics. Perhaps it is not so surprising that this is so, after all. As Koyré expresses it: the world-clock made by the Divine Artifex was much better than Newton had thought it could be. Every progress of Newtonian science brought new force for Leibniz’s contention: the moving force of the universe, its vis viva did not decrease; the world-clock needed neither rewinding nor mending. The Divine Artifex had therefore less and less to do in the world. He did not even need to conserve it, as the world, more and more, became able to dispense with this service. Thus the energetic God of Newton who actually ‘ran’ the universe according to his free will and decision, became in quick succession, a conservative power, an intelligentia supermundana, a ‘Dieu fainéant’. Laplace, who, a hundred years after Newton, brought the New Cosmology to its final perfection, told Napoleon, who asked him about the role of God in his System of the World: ‘Sire, je n’ai pas eu besoin de cette hypothèse.’ But it was not Laplace’s System, it was the world described in it that no longer needed the hypothesis God. ([10.4], 276) But if Leibniz’s determinism had taken over the Newtonian system of the world, it was not by providing mechanism with a new pre-established harmony. Laplace’s determinism is one in which the particles at a given time, with their positions and momenta, determine once and for all the future and past states of the world; but this is not any explanation for the existence of forms or purposes (real or apparent) other than in the form of an unencashable promissory note. The positions taken on these issues by scientists in the nineteenth century are varied and complex. The variety spans many intermediate forms between the two extremes which are represented here as mechanism and teleology. In the nineteenth century, both philosophers and scientists had become determinists. Only the form of determinism separated the two. The mechanists had come to adopt physical determinism, a determinism by mechanical forces alone, whereas the philosopher followed Leibniz in seeing in the system (or harmony) of the world such things as forms, their essences, purposes and purposeful beings (spirits). All of these were found by the philosopher in a simple ‘common-sense’ examination of the world. The pre-established harmony that was once postulated between minds or monads was now postulated to explain the adaptation of life forms. In this manner the pre-established harmony came to be regarded as a grand design in which physical organisms were adapted one to another. Even the description of development in an organism, in the work of von Baer, for instance, shows allegiance to both a mechanical perspective and a ideological perspective, tempting some modern commentators to call it ‘teleomechanism’, though this term would also apply to theologically inclined strict mechanists of the period as well (e.g. the geologist Hutton). William Paley likened a living organism to a watch: if we were accidentally to find a watch, would we not postulate a watchmaker? The wonderful way in which all of the parts of the watch fit together allows us to infer that there must have been a watchmaker. In much the same way, the extraordinary manner in which living forms are adapted to their very particular surroundings, and often unable to survive in certain very slightly changed surroundings, suggests a designer. But it is not the existence of a designer which is the problem, but of a design or a plan. Many mechanists were faithful believers. They might still find a pre-established harmony to be unpalatable, given the success of modern mechanical science. The existence of forms on earth had thus taken a particular twist late in the eighteenth and early in the nineteenth century: the fact that Scholastic forms are evident among phenomena is embarrassing enough for modern science. But the extraordinary coincidence that the various forms were uniquely fitted or adapted to their surroundings made them a double embarrassment to a mechanist. In order to respond to this challenge, Lamarck proposed his theory of evolution, in which all living forms metamorphose into other forms as they strive to make best use of the environment. Over the ages, thus, the various forms come to fit their surroundings with all the appearance of design, without a designer. (Other precursors of evolutionary theory and/or metamorphosis, include David Hume, Erasmus Darwin and Goethe.) There were two difficulties with Lamarckian evolution: the concept of ‘striving’ was still a difficulty for a thoroughgoing mechanist. But this was not such a difficulty if one were also the kind of thoroughgoing mechanist who might be called a ‘vitalist’. A more fundamental difficulty than that was a methodological flaw which arose in the usual defence of its main thesis. We turn to this difficulty of the theory of evolution, which was solved by Darwin. Darwin’s reconciliation of scientific metaphysics and method Newtonian mechanism was not merely a set of ever-changing mathematical laws of motion; it came also with a distinctive method. Newton espoused an experimental method, which was both championed and practised with great success in many fields of science, old and new. The success of modern science was attributed to the adoption of Newton’s experimental method, which enjoined a close study of the facts and a repudiation of all hypotheses. If we study the great debate between evolutionists before Darwin and their opponents concerning evolution, we find however that it is their opponents who were clearly scientific in their treatment of phenomena. The celebrated debate in 1830 in the French Academy between Geoffrey St Hilaire, who defended Lamarck, and Cuvier, who ridiculed evolutionary theory, was a clear defeat for the evolutionists. Cuvier was a remarkable comparative anatomist. He had minutely studied the skeletal structure of a great many animals. On the basis of measurements he was able to establish ratios between skeletal limbs of a great variety of species. The minute and exhaustive studies of bones allowed him to reconstruct entire skeletons from a few fossil bones, sometimes from a single bone. Cuvier came to be regarded as the Newton of comparative anatomy, for such were his accomplishments in that subject. In 1812, Cuvier had come forward boldly to assert that a study of the fossil record for different ages revealed that the earth had entirely different species from time to time inhabiting it. This evidence, he claimed, was compatible only with the catastrophic destruction of species and subsequent creation of a new collection of living forms during successive ages on earth. The facts he collected left him no other choice that he could imagine but cycles of destruction and special creation. The evolutionists (e.g. Lamarck or his follower Geoffrey St Hilaire) could not challenge Cuvier’s claims about the existence of these very different species in successive ages on earth. Cuvier’s scientific method was too rigorous to allow that counter-attack. His techniques continue to be useful in palaeontology and comparative anatomy even today. The best that an evolutionist could do was to suggest a possible mapping between species in one age and the next to show how one set of species might have metamorphosed into an entirely different one in the intervening period between two fossilizations. But so far apart were the species in different ages that the suggested pathway from one form extant in one age to one extant in another was sometimes fantastic. Evolutionists seemed to be dreaming up their models of change, where the hard-nosed scientist who studied the established facts would be fully on the side of Cuvier, the consummate observer of minute and detailed facts about anatomy in different species. For a philosopher of biology this debate is instructive not only because we now admire an idea that was once regarded as an unscientific speculation. It is also instructive because it is a clash of opinion between an ingenious metaphysical solution to a dilemma of Newtonian mechanics and a rigorous application of Newtonian method. The facts are, as they were then known, clearly investigated by Cuvier in a scientific manner. The evolutionist, on the contrary, appears to be a dreamer, a myth maker. The Lamarckian hypothesis defended by Geoffrey St Hilaire seems to be methodologically flawed, because it is an hypothesis (of the kind that Newton would not feign), and not an experimentally established statement, such as Cuvier’s. This clash of opinion is of seminal importance. Lyell formulated a ‘uniformitarian’ geology in contradistinction to Cuvier’s catastrophic theory of the history of the earth. This clash changed the way in which uniformitarians and evolutionists approached their subject. The vicious attack on evolutionism on methodological grounds made subsequent uniformitarians and evolutionists nervous for decades about proposing hypotheses. Darwin would not publish until he had investigated a great many particulars, perhaps more than absolutely necessary for the purpose of promulgating or defending their views. Darwin himself, whose evolutionary theory was of a different kind altogether, nevertheless immersed himself in the study of minute details of living things before coming forward with his views, which made his work both immensely richer and much less accessible to contemporaries than it might have been. Some controversies following Darwin’s writing may be attributed to a lack of understanding of its main features, which were sometimes not clear to everyone, so great was the mountain of factual evidence in which it was lost. But an echo of Cuvier’s earlier critique remains to this day: the fossil record, they say, is too incomplete to warrant evolutionary theory. The case for evolution cannot be made with so many gaps in the evidence. In the methodological developments of the nineteenth century it became evident that this demand is too great to make of any theory. Suffice it to say that the fossil record cannot support Cuvier’s view either. If evolution is fantastic, then repeated extinction and creation are equally fantastic, without further evidence. The critical feature of the evolutionary theory of Geoffrey St Hilaire and Lamarck which made it unsatisfactory is that this form of evolution did not allow for the extinction of species. Darwin’s theory of evolution by natural selection does. The fossil record from one age to the next may be very different; and it may be futile to seek a one-to-one correlation between a species in one age and its descendants in another. Darwin suggests that even if most species in an age become extinct, a few which survive will produce all the variations which populate the next age. To take a popular example, it would be futile to look for an evolved successor today to every dinosaur which once roamed the earth. But there may well be one form (archaeopteryx) from which have evolved all the birds of today. Cuvier believed in mass extinction during the ice ages, and Lamarck in no extinction but only evolution. Darwin’s theory is successful because it allows for almost complete extinction, and for evolution as well. Darwin’s theory of evolution by natural selection postulates that there is a large amount of small variation in offspring. His proposal of blind variation combined with natural selection resolved the scientific and metaphysical issue of how form and purpose may arise—or may seem to do so—in a material and mechanistic universe. In one theory, he was able to defend the mechanistic conception of the world in a manner which was compatible with detailed study of fact. Newtonian method and Newtonian metaphysics were reconciled, and a major philosophical problem for Galileo’s science was solved. There is nowadays some confusion about the form of gradualism which is necessarily entailed by Darwin’s theory and a form of catastrophism which is compatible with it: Darwin’s theory is often described as gradualist in the sense that there are no catastrophes in the history of the earth. This form of gradualism is not appropriately attributed to Darwinian theory. The hypothesis that the extinction of a very large number of dinosaur species in a very short period of time by the catastrophic event of a meteor striking the earth is certainly not a critique of Darwinian theory. But the evolution of subsequent lifeforms would be described by a Darwinian as descent from the surviving life-forms then extant, and this evolution would be gradual in the specific sense that the evolution would depend on small variation within species and their differential advantages. Whereas Lyell’s geology denied the assumption that there are regular catastrophes, Darwin’s theory describes how to do without periodic bursts of creation de novo. On Darwin’s account, the evolution of species does not show leaps of creation, though it may well undergo rapid destruction of species in what may be described as catastrophes. Two of the three Scholastic phenomena which could not be fitted into mechanistic theory were reconciled with it in Darwin’s model. Forms (species) were described as mutable, but apparent at a given time; and the appearance of a great purpose or a grand design was also feigned in nature by the almost adaptive character of living forms which had been naturally selected in their environment in competition with variations which become extinct. Continuing issues in the philosophy of biology After Darwin successfully promulgated his theory of evolution by natural selection, an entirely new set of issues in the philosophy of biology came to light which were only dimly realized before. Form and species One of these issues concerns the classical idea of form. There may be a certain sense in which the mechanical conception of the universe challenged the idea of forms as the basis of all knowledge. Certainly, in some subjects in which mechanics was successful, forms ceased to play an important role. Many were the subjects, however, which resisted the advent of mechanical theories. The study of form in animals, plants and minerals (particularly crystals) left forms as a fundamental category for our knowledge. In classifying species of plants, for instance, Linnaeus and Buffon provided rival schemata. Buffon’s nominalist scheme was more general and philosophical, whereas that of Linnaeus, which stressed the essential qualities of species, was found much more useful in the practice of classification. Whichever system of classification one adopts, it is necessary for the practising natural historian, in order to classify things according to their form, to presuppose that each species has a characteristic form, which may be captured in a typical specimen. Abnormal individuals may be found, of course, but the natural historian had to guard against choosing one of them as a specimen, which difficulty prompted Buffon’s doubts about essential properties. An elaborate methodology had been developed to pursue natural history to respond to these concerns, the recounting of which falls outside the scope of this essay. Darwin’s theory of evolution by natural selection undermines the theoretical basis for this enterprise. Species, according to Darwin are not fixed but constantly changing. The normal situation is an abundance of variety in offspring. Thus in any species the characteristic form is not one but a multiplicity. Are there such things as species at all? (This is not quite the traditional problem of natural kinds and realism, though perhaps related to it.) Darwin did not deny that an examination of the flora and fauna around the earth would yield a knowledge of identifiably different species. As a young man he delighted in collecting beetles. He did not need to be reminded that identifying forms is what makes the practice of natural history possible. His claim is a historical one: Darwin envisaged living organisms as belonging to a single tree. As the branches fanned out, some lines would come to an end (the forms would become extinct) but some would continue to flourish and would produce numerous varieties. Given a cross section of time the tree would project on a plane the characteristic grouping together of living things into species, genera, etc. as we find these in our records. But there are two provisos: Firstly, there are always some variations, and these are the source of evolutionary change. Secondly, over time, we recognize that species are mutable, and organisms from one species will be seen to have a common ancestry (and therefore share formal similarity) with the most remote of living organisms if only we are willing to go back far enough on the tree of life. Darwin’s theory eats its cake and has it, too. Species have characteristic properties more often than not, because the process of natural selection may well isolate a form of life as a species. This is what makes Linnaean natural history possible. But within any species there are many small variations, which will, in the course of time, speciate. Because species change in this manner, each existing variation has equal right to be regarded as characteristic of the species—or better still, it is the variety which characterizes the species. So Buffon is perhaps right after all in denying the existence of essences to living forms. This conception of mutability challenged the idea of ‘sorts’ or ‘kinds’ as fundamental to our understanding of living organisms. In the theory of collections or aggregates or classes, it is possible to take any aggregate and regard it as a class. If any collection is a class, is there anything special about a species considered as a class? Is there some way in which it is natural, and not artificial? From the old conception of morphology, it is only their form which binds similar organisms into a species. But when we consider Darwinian evolution, a species must be understood as a class of organisms which share the ability to generate common offspring. Thus we find in Darwinian theory a criterion for describing a class, when it is a species, as a natural kind. There are no doubt difficulties with this. For one thing, inability to generate offspring may be due to separation in time or by geography, which leaves it an open question whether two separated groups belong to the same species when they do not generate common offspring, even though we may suppose that they could. On the other hand some combinations of animals may have only sterile offspring, or have offspring which are sterile after one or two or more generations. For all these and still more reasons the notion of a species has become both richer and more troublesome since Darwin. The criterion of form or essence to identify specimens, however practical and useful, is usually undermined by the existence of variety, and has been seriously undermined as a fundamental tool of biological thought. Quite recently, this issue has been raised again under the slogan ‘species as individuals’, i.e. the idea that any one species is not a class of objects similar in some respect but an organic unity. This twentieth-century discussion seems to contribute little to what Darwin had already considered apart from obscuring the perfectly good notions of class and of individual. The theory of classes allows any collection to be also considered as an individual if we so wish; one might even wish to say that that is its whole point. Considering a species as an organic unity does not deprive it of its status as a class of organisms, any more than the class of cells within an organism is denied status as a class because they are all part of one organism. In both cases the defining property of the relevant class may be a historical one. All (or almost all) the living cells in the body of Georg Cantor have the property of having descended from one fertilized egg from his parents. They form a class none the less, as defined by that property, and Georg Cantor was an individual all the same. History and determinism Another fundamental issue of interest to philosophers to emerge from evolutionary theory is the conception of an ‘open’ history. Darwin’s account of evolution included an idea of small variation in great abundance which has been variously described as ‘blind’ and ‘random’. The inability of the environment, or of the organism, to direct the variation in the offspring is a very fundamental feature of Darwinian evolutionary theory. In order to distinguish the first view which was proposed by Darwin from a theory which allows organisms to have offspring which inherit the good acquired characteristics of the parent, the latter is often called ‘Lamarckian’. Darwin himself vacillated between giving Lamarckian and what we may wish to call Darwinian accounts of adaptation. Climateinduced or environment-induced variation would be a third variety, which we may wish to call Lyellian evolution, to commemorate Lyell’s views on it in his Principles of Geology. What is interesting from a philosophical perspective about Darwin’s distinctive theory (even if he sometimes used other theories also) is that in his account there is an element of chance in the evolution of species which cannot be eliminated. A chance event here and now could have a profound influence upon the course of the future history of life on earth. Indeed, the entire history of life is a history of many chance events which produce the appearance of a pre-established harmony (or what is more neutrally called ‘adaptation’). It may seem at first that this is a peculiarity of biology that it raises chance to such an important level of fundamental principle, though we have seen it repeated latterly in thermodynamics and quantum mechanics. Although Darwin was not technically a statistician, his conception of the biosphere was a fundamentally statistical one. His theory gave the statistical view, itself adumbrated earlier in the nineteenth century, considerable scope for development, although this development had to await the ‘new synthesis’ of Darwinian theory of selective fitness with Mendel’s theory of genetic inheritance, and Waismann’s theory of the eternal or at any rate long-living germ line. Among nineteenth-century philosophers, Peirce is perhaps the only philosopher to adopt this indeterminist consequence of Darwinian evolution. There are many philosophical problems concerning indeterminism, statistics and probability, and chance that are of interest to a philosopher of biology, though only in forms evident in the twentieth century. Methodology When Darwin wrote his Origin of Species, there was almost universal agreement that any scientific theory, to be successful, must describe the world as fully deterministic. The indeterministic theory of Darwin with a prominent place for chance within it creates a methodological difficulty. Whether it is a methodologically satisfactory theory or not can be asked while assuming that a theory must fit the model of theories in physics as then conceived. In the nineteenth century this was not as great an enigma as it became in the twentieth, when methodologists frequently worried about the methodological status and explication of Darwinian evolutionary theory. In the nineteenth century, and indeed to this day, the central methodological difficulty raised about Darwin’s theory of evolution by natural selection is that the record of facts (i.e. fossils) is incomplete. Darwin’s theory may be described for that reason as unfounded, or poorly founded. Alternatively we may dismiss the methodology which demands so much of Darwinian theory or of any other, for that matter, as an unrealistic methodology to adopt. Compared to methodologies propounded in the nineteenth century, theories of method in the twentieth are much more varied and much less demanding. Foundationalism is in doubt today more than ever. It would be a mistake, however, to think that Darwin’s theory had a great deal to do with this change. All the evidence seems to suggest, rather, that methodology has developed more in response to problems in mathematics and in physics, and less in response to those in biology, even though the present scepticism concerning foundations fits Darwinian science extremely well. Although the influence on methodology of reflections upon the development of evolutionary theory is minimal, the same is not true for reflections on the content of evolutionary theory. Darwin was among those who realized that his theory implied that all life including human life has evolutionary origins. In his Evolution of the Emotions in Animals and Man, Darwin sought to extend his theory explicitly to human feeling. We also know from his diaries that he regarded human intelligence and some critical ideas to have been inherited, too. In fact a case can be made that Darwin was a follower of Whewell until he became a Darwinian in 1839 when he realized that a substitute for what Whewell had called fundamental ideas (which are not derived from experience) could be understood as having been inherited from our simian ancestry [10.3]. An evolutionary epistemology promises to be one of the most fundamental and profound philosophical consequences of Darwinian evolutionary theory, though what it is exactly remains undecided. Morality The mechanical conception of the universe still fails to accommodate one class of Scholastic phenomena, concerning morality. Where evolutionary epistemology is clearly an interesting subject with much to teach us, evolutionary morality is, like a mechanistic conception of purposes in the seventeenth century, still enigmatic. Whereas Darwin’s account shows how to do without a grand design, and how to explain the existence of forms among living organisms, there is in evolutionary theory as yet no satisfactory theory of the existence of morality. There is of course ample room to account for the fact of the existence of mores among groups of people. Just as we can study different animals to study their mating, nesting or feeding behaviour, so too we can observe humans in different groups and study them moralizing. This might lead us to think that we have an evolutionary understanding of morality if we have some explanations of how they come to acquire their moralizing habits, but that would be a mistake. The characteristic feature of morality is not that we behave in some way, or moralize in some way, but that we regard some behaviour as immoral or wrong even as we practise it. What needs to be understood is how it comes about that some things are wrong, or immoral, and not just why we so regard them. The understanding of morality from an evolutionary perspective certainly had a controversial and well publicized attempt in the nineteenth century. One of Darwin’s most ardent admirers, Herbert Spencer, proposed a doctrine called Social Darwinism. In this doctrine the lesson for us from competing living forms as Nature evolves (red in tooth and claw), is that the fittest survive, and the weak perish. Applied to the social sphere it led to what was roundly attacked as an amoral and callous view of human society. Its popularity with some despicable political movements in the twentieth century (e.g. with the National Socialists, or Nazis) has left many intellectuals with a horror of social theoretical biologists. But the issue of morality is squarely one which remains unresolved within the Galilean revolution, and, however distasteful and misguided Spencer’s Social Darwinism, one must give him and other intellectuals of the nineteenth century credit for recognizing this as a fundamental difficulty of modern science which needs to be addressed. Indeed it is because an entire society under the Nazis, in the name of their entire society, espousing Social Darwinist slogans, was so immoral as to practise systematic murder and genocide that we have to ask not only how individual immorality is possible but also how collective immorality is possible. No account of how actual mores are acquired or propagated can explain this. As opposed to Spencer, who tried to extract a morality from the natural course of events as he interpreted them, G.E.Moore argued early in the twentieth century that any attempt to derive a claim that something must be so based on the claim that it is so, is a fallacy (what he called the Naturalistic Fallacy). His argument is that of whatever is described as a fact we may still ask meaningfully whether it is good that it is so. Since we can always meaningfully ask that question, we cannot identify the meaning of ‘good’ with what is the case. Moore’s argument purports to make the realm of morality (and of norms and prescriptions generally according to later philosophers) independent of the realm of nature. How it may have come about that these realms are independent is a difficulty for naturalists. The situation at the turn of the twentieth century was that naturalism in ethics was opposed to normativism, and the matter was unresolved, and so it remains to this day. METHODOLOGY OF BIOLOGY Origins of the subject and of some terms Whether there was any philosophy of biology in the nineteenth century is debatable: there is as good reason to deny it as to assert it. The expressions ‘philosophy of science’ and ‘philosophy of biology’ were invented in the nineteenth century by William Whewell. Were we to rely on that alone we would have to allow that there is such a subject by 1840. But if we were to seek practising philosophers of biology, none comes to mind, at least none who would self-consciously describe any of their work as belonging to such a field. The name invented by Whewell for this field came to designate something which clearly exists only in the latter half of the twentieth century, with some writings of T.Goudge and J.H.Woodger. Later, the writings of D.Hull, still later followed by a host of interesting writers on the subject (Ghiselin, Ruse, Wimsatt, Sober), all of whom would be happy to describe their relevant works as belonging to the philosophy of biology. To a modern historian of the philosophy of biology in the nineteenth century this creates an interesting question of choice: lacking a clearly defined field in the nineteenth century, one could dismiss it as non-existent. This implies that there is no philosophy of biology until concerns arising out of logical empiricism (a unique intellectual movement of the twentieth century) led to the birth of this subject. But this would belie the fact that many of the issues taken up today did arise earlier, as we have seen, however different the context in which they arose in the nineteenth century. The strategy which suggests itself is to pick out issues in the philosophy of biology today and to seek to present these very issues as they once emerged or developed in the nineteenth century. This is the strategy which has been adopted in this chapter. The obvious difficulty with this strategy is that it may be prone to anachronism: how do we prevent our criteria of choice of issue from imposing our own concerns for those of the past? To a certain extent this is unavoidable. In writing a history of philosophy in the nineteenth century, or in writing a history of the subject of history, there would be a generally accepted sense at the time in the period being studied that some things were within the field, even if today they were to be classified as belonging elsewhere. Issues in psychology or in sociology, for instance, which arose in the early part of the nineteenth century would have to be classified as part of philosophy because they were so regarded then. In this sense we cannot find a bench mark or a criterion of what would have been part of the philosophy of biology in the nineteenth century as seen by a contemporary then. But to be forewarned was to be forearmed. The issues of the philosophy of biology may be divided into two kinds: methodological, and substantive. There is, as I shall soon suggest, an overlap there as well. The substantive questions within nineteenth-century biology which are of concern to philosophers of biology today may be classified into three categories: those connected with problems of evolutionary theory and related developments; those connected with the problem of reduction of life sciences to physics and chemistry; and those related to the understanding of human beings in the light of modern biology. There are of course a host of issues which may fit within or across these categories. All these issues were already controversial in the latter part of the eighteenth century and continue to attract interest to the present day, and some of them have been sketched in the first section above. In studying the methodology of biology in the nineteenth century one could include the commentators on science (Whewell, Bernard) or those involved in the practice of scientific research who exhibit or are obliged to pronounce upon method (Cuvier, Pasteur, Darwin): the discussion of methodology in the practice of scientific research is generally a sign of a clash between defenders of different theoretical perspectives, all of whom attempt to use methodological considerations to buttress their respective cases. The second kind of methodological pronouncement is usually controversial, because it is made in the interests of controversy. The substantive issues in biology which stand out today as worth discussing are just those that were once the subject of controversy. Practical methodology is therefore closely bound up with the same substantive issues that we have identified as part of the philosophy of biology in the nineteenth century. There may also be a connection between the writings of abstract methodology and the controversies of the nineteenth century: Whewell’s work may be related to the controversies arising from substantive issues in physics (empiricism versus a, priori knowledge, for instance) and Bernard’s from those in medicine (anatomical as opposed to physiological considerations in medical research). Nevertheless, the form of these selfconsciously written methodological tracts differs from the others: the former must be taken literally as methodologies. The others are more casual and less systematic remarks uttered in the interests of other argumentation. We may sometimes disregard the methodological apologia and prefer instead to analyse the science in action. For this reason there has been included, in the section below, a brief account of two methodological treatises of the nineteenth century of particular interest to the philosophy of biology. Since the unification of biology is an important part of the story recounted here, perhaps some comments are in order about each of the subjects of history, philosophy and biology as they are found in the nineteenth century. The first two of these subjects trace their origin to an era which is at least as early as that of the ancient Greeks— Herodotus and Socrates respectively being cited as their originators. (The words were invented then, but it is always possible to suggest that there were predecessors in or around ancient Greece, or in another civilization prior to the Socratic invention of the word.) Philosophical history, a particularly influential conception of time and events in human history, seems to be an especially noteworthy product of the nineteenth century (Hegel, Comte, Marx). It is an open question which will not be taken up here what direct or indirect influence philosophical history might have had on biology. Unlike philosophy and history, biology is a comparative beginner. It is recognized as a unitary and integral subject worthy of a separate designation for the first time only late in the eighteenth century. Many of the fields which are now part of biology as we understand it have a hoary history: zoology, botany, physiology, anatomy, as well as hosts of sub-disciplines like ornithology, entomology. They were well developed subjects for a long time before they came to be regarded as component parts of a single subject identified as the science of life, or of biology. It is an interesting fact about this new subject, biology, that there is a philosophy of it according to us. In contrast, we would find a philosophy of entomology or of botany to be unnecessary without further argument. It seems that there is a unity to biology which warrants a philosophy of it. Perhaps the thesis that the unity of biology is a unity of philosophical approach, prompted by the fundamental problems of modern philosophy, is not the whole story. But if it is part of the story, it still makes philosophy much more central to the development of biology, and vice versa, than is generally supposed. Two important methodological treatises The origin of the expression ‘philosophy of science’ may be traced to Whewell, who proposed it in his book Philosophy of the Inductive Sciences, Founded upon Their History (1840). Book IX is entitled ‘The Philosophy of Biology’, which is part of the philosophy of science. The advances which have, during these last three centuries, been made in the physical sciences;—in Astronomy, in Physics, in Chemistry, in Natural History, in Physiology;—these are allowed to be real, to be great, to be striking: may it not be then that these steps of progress have in them something alike?—that in each advancing movement there is some common process, some common principle? Then a little later he says, ‘if we can, by attending to the past history of science, discover something of this common element and common process in all discoveries, we shall have a Philosophy of Science’ ([10.5], vi). In the opening section of Book I, philosophy of science is said to offer nothing less than a complete insight into ‘the essence and conditions of all knowledge, and an exposition of the best methods of the discovery of all truths’. It is evident that a philosophy of science would include at least a methodology, and an informed analysis of the history of science to exhibit that methodology. In addition it would have to exhibit an insight into all real knowledge—a tall order indeed. Whewell’s own writings are remarkable for the insight he exhibits into diverse subjects and their history, which few have matched. But when we turn to his account of the philosophy of biology, the reading is disappointing (but no more than Mill, Comte or Spencer). There he lists five schools of biological thought, and a cursory account of some developments in physiology. We do not find any especially remarkable insight into the essence and conditions of biological knowledge, or even of the particular methods which may have made them successful. Instead, we find that when he can he applies the paraphernalia of a philosophy arrived at from the study of physics and mathematics to biology—his conception of a fundamental idea not derived from experience, for instance, is inspired by Kant’s conception of a priori synthetic judgement, introduced to show how mathematical knowledge is possible. Searching for a nineteenth-century figure who actually studied what Whewell may have called the essence and conditions of biological knowledge and who reflected upon the process of discovery to extract some insight from it, we find only one book which merits our attention, Claude Bernard’s classic, An Introduction to the Study of Experimental Medicine (1865). Claude Bernard was one of the great physiologists of his day. His most memorable achievement perhaps was the discovery of the internal environment of animals, which allows for an explanation of the comparative autonomy of some animals even though they remain in constant interaction with environment. He had also made numerous and brilliant discoveries in physiology before that, such as the function of the pancreas, animal glycogenesis, experimental production of diabetes, the existence of vasomotor nerves, which are mentioned among other discoveries in Paul Bert’s introductory eulogy ([10.2], v-xii). Claude Bernard’s work does not address biology as an integral subject. He deals exclusively with physiology, and mentions anatomy. But his work is so centrally in philosophy of biology as we now understand it that it cannot be left out of account. Bernard argues forcefully for the need to study not just form as in comparative anatomy but function as well. And he suggests that in order to do so it is necessary not just to observe organisms but to experiment with them. What, we may ask, is the difference between observation and experiment? Bernard provides us with one of the most lucid and brilliant accounts of experimentation and experimental reasoning ever given. He begins by distinguishing the process of experimentation from that of observation. We take observation to be a passive gathering of facts, where in experiments there is an intervention into the process being studied, ‘a variation or disturbance that an investigator brings into the conditions of natural phenomena’ ([10.2], 5). But in distinguishing an observation from an experiment and both from experimental reasoning, he notes that the objective of an experiment is to understand a phenomenon from a perspective under our own control, ‘to reason experimentally, we must usually have an idea and afterwards induce or produce facts, i.e. observations, to control our preconceived idea’. ([10.2], 20). Bernard’s account of the experimental method in observations as well as in experimentation is anything but passive. ‘Of necessity, we experiment with a preconceived idea. An experimenter’s mind must be active, i.e. it must question nature, and must put all manner of queries to it according to the various hypotheses which suggest themselves.’ And his account of the experimental method is this: the metaphysician, the scholastic, and the experimenter all work with an a, priori idea. The difference is that the scholastic imposes his idea as the absolute truth which he has found, and from which he then deduces consequences by logic alone. The more modest experimenter, on the other hand, states an idea as a question, as an interpretative, more or less probable anticipation of nature, from which he deduces consequences which, moment by moment, he confronts with reality by means of experiment. ([10.2], 27) Bernard’s brief for a study of experimental medicine is an attempt to bring science to bear on a subject which he saw then as still in the shades of empiricism and suffers the consequences of its backward condition. We see it still more or less mingled with religion and with the supernatural. Superstition and the marvellous play a great part in it. Sorcerers, somnambulists, healers by some virtue of a gift from Heaven, are held as the equal of physicians. Medical personality is held above science by the physicians themselves; they seek their authority in tradition, in doctrines or in medical tact. This is the clearest of proofs that the experimental method has by no means come into its own in medicine. ([10.2], 45) The conception of experimental medicine proposed by Bernard suggests that experimentation has exactly the same character whether we experiment on inorganic chemicals or on living tissue. Thus he argues that there is just one method for the study of all living and non-living things, which is in direct contrast to the claims of some vitalists that living organisms provide exception to the general rules governing the study of dead (non-living) matter. While Bernard argued forcefully and lucidly for the unity of experimental method, he also pointed out that living objects must be treated differently from inorganic things. So far we have been explaining experimental conditions applicable to both living and inorganic bodies; for living bodies the difference consists merely in the greater complexity of the phenomena…. But in the behaviour of living bodies we must call the reader’s attention to their very special interdependence; in the study of vital functions, if we neglected the physiological point of view, even if we experimented most skilfully, we should be led to most false ideas and the most erroneous deductions. ([10.2], 87) Living organisms must be treated as a harmonious whole. And in this manner he argues for the need to do not only comparative anatomy but experimental medicine as well. The greatness of Bernard’s suggestions lies not only in the profound changes that he foresaw and helped advance in the profession of theoretical medicine but also his genuine contributions to methodology, or to the philosophy of science as this subject had been conceived by Whewell. Bernard’s analysis of the sceptical doubt which is used by the experimenter without letting it get out of control, his defence of the need for preconceived ideas together with the injunction that we must be ready to abandon them as soon as nature turns recalcitrant—all these are so remarkable in capturing the essence of scientific method that it is one of the few books on methodology which continues to be read as profitably now as when it was first printed. Compared to Bernard’s brilliant work, there is nothing else of interest in the nineteenth century, and perhaps even since then, in the form of a sustained methodological treatise on the topic of experimental method in biology. NOTE My thanks to Professor Margaret Schabas and Mr David Clingingsmith for their comments and assistance with the paper; the errors which remain are of course my BIBLIOGRAPHY 10.1 Alexander, H.G., ed., The Leibniz-Clarke Correspondence, Manchester: Manchester University Press, 1956. 10.2 Bernard, C. An Introduction to the Study of Experimental Medicine, 1865, trans. from the French by H.C.Greene, 1927, reprint New York: Dover, 1957. 10.3 Curtis, R. Charles Darwin and the Refutation of Whewellian Metascience: How The Philosophy of Science Learned from the History of Science, Ph.D. Dissertation, York University, 1982. 10.4 Koyré, A. From the Closed World to the Infinite Universe, Baltimore: Johns Hopkins University Press, 1957. 10.5 Whewell, W. Philosophy of the Inductive Sciences, 2nd edn, 1847, reprint London: Frank Cass, 1967.
Routledge History of Philosophy. Taylor & Francis e-Library. 2005.
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