Acta Biotheoretica 27, 3/4:201-235 (1978) DARWIN'S EVOLUTIONARY PHILOSOPHY: THE LAWS OF CHANGE EDWARD S. REED* Boston University, Department of Philosophy (Received 31-X-1977; revised 12-XII-1977) ABSTRACT The philosophical or metaphysical architecture of Darwin's theory of evolution by natural selection is analyzed and discussed. It is argued that natural selection was for Darwin a para- digmatic case of a natural law of change - an exemplar of what Ghiselin (1969) has called selec- tive retention laws. These selective retention laws lie at the basis of Darwin's revolutionary world view. In this essay special attention is paid to the consequences for Darwin's concept of species of his selective retention laws. Although Darwin himself explicity supported a variety of nominalism, implicit in the theory of natural selection is a solution to the dispute between nominalism and realism. It is argued that, although implicit, this view plays a very important role in Darwin's theory of natural selection as the means for the origin of species. It is in the context of these selective retention laws and their philosophical implications that Darwin's method is appraised in the light of recent criticisms, and the conclusion drawn that he successfully treated some philosophical problems by approaching them through natural history. Following this an out- line of natural selection theory is presented in which all these philosophical issues are high- lighted. I. INTRODUCTION: DARWIN AND THE METAPHYSICS OF MODERN SCIENCE A great deal of twentieth century philosophy about science has been con- cerned to reveal the metaphysical architecture of modern scientific thought. However, as the title of E. A. Burtt's classic The Metaphysical Foundations of Modern Physical Science reveals, the emphasis has been on the metaphysics of physics, not science in general. Even the two most renowned philosophies of life and life science, Schr6dinger's and Whitehead's, are the work of physi- cists, and are concerned mostly with problems in modern physics. It is only quite recently that the philosophical underpinnings of biological theory have even begun to be discussed. And, more often than not, many contemporary works on foundations of biology follow in Schr6dinger's tradition: they attempt to bring theoretical physics to bear on biology, they do not attempt to develop intrinsically biological ideas (e.g. Simon, 1971). * Current address: Department of Psychology, University of Edinburgh. 202 EDWARD S. REED There is, however, much that is philosophically important in biological theory, and perhaps the most fruitful area to be cultivated is the Darwinian theory of evolution. Evolutionary theory serves not only to unify the disparate range of biological inquiry, but also shows a vast amount of philosophical promise. These philosophical riches are visible only after the traditional mis- conceptions about Darwin as a thinker are overcome. It has often been the fashion to picture Darwin as a rather quaint naturalist with an eye for detail and a mind which became confused when engaging in theory (Darlington, 1960; Himmelfarb, 1959; Irvine, 1955). This traditional misapprehension has been thoroughly laid to rest by Ghiselin's penetrating new insights, interpreting Darwin in the light of his entire corpus, and also by the publication of Darwin's 'Notebooks on Man, Mind and Materialism' (Gruber and Barret, 1974). It is no longer legitimate for the philosophically minded to dismiss Darwin's theore- tical framework; in fact, it is now possible to place Darwin's philosophical and theoretical framework in the context of philosophy of science and of the meta- physical foundations of modem science. According to Burtt (1932), Koyr6 (1957) and others, the Medieval, teleo- logical, humanity-oriented, finite world view was overthrown by the rise of cosmological thought from Copernicus through Newton. 'Every progress of Newtonian science,' observed Koyr6 (1957: 276) 'brought new proofs for Leibniz's contention: ... the world clock needed neither rewinding, nor mending,.., the Divine Artifex had therefore less and less to do in the world'. Eventually, Laplace remarked that God was an 'unnecessary hypothesis' on this new world view. Although Laplace found God an unnecessary hypothesis, the concept of a 'Divine Artifex', a Godly creation of the world, is not inconsistent with Laplacean science. Physical science had replaced a teleological world view with a mechanistic one, but only in science. The issue of Design was not directly addressed by Newtonian cosmology -and, indirectly, this cosmology implied that the world was not only a machine, but a machine designed by God (Koyr6, 1957, passim). Indeed, the strongest proponents of physical science in the early nineteenth century advocated the view that God was the Creator. On the European continent Kant (and others) found a realm of religion alongside the realm of Laplacean science, as did the naturalistic followers of Goethe and Cuvier - all these thinkers pointed to God as the Creator of the world. In England, the most renowned scientists, theologians and philosophers con- tributed to the 'Bridgewater Treatises' which were the monuments of Natural Theology. Men such as Babbage, Bell, Butler, Herschel, Paley and Whewell all advocated the doctrine of the treatises, that God created our clockwork world and that science is the ingenuity by which we uncover the mechanisms of God's design. Darwin's philosophy was a revolt against this deeply ingrained tradition DARWIN'S EVOLUTIONARY PHILOSOPHY 203 of Design and Natural Theology. For Darwin, the 'origin of species' was due not to God's work, but 'by means of natural selection'. At times, Darwin was not convinced his theory disproved a Godly creation (or he was being careful of what he said publicly). He quotes Whewell (from a Bridgewater Treatise) on the title page of The Origin of Species: But with regard to the material world, we can at least go so far as this -we can perceive that events are brought about not by insulated interpositions of Divine power, exerted in each particular case, but by the establishment of general laws. Darwin was publicly satisfied to hint that God may have designed natural selection by breathing life into the first organism (but see Darwin, 1868, II: 430-2). Yet, privately, Darwin was unsatisfied to let God even create that first creature. He wrote to Hooker in 1871, speculating on the chemical origins of life (F. Darwin, 1888: 18; see also J. D. Bernal, 1967: 4) and regretted vigor- ously his public intimation that God breathed life into the first creature. Darwin's antipathy to Design was a consequence of careful observations guided by his new theory of the natural economy. Before Darwin, scientists attempted to discover the 'nature of things' in laws and causes, but Darwin felt that laws were well developed working hypotheses about what was happen- ing in nature. Before Darwin, the laws of nature were most often seen as an expression or representation of timeless truths or as conventions. Natural law was often just another name for Divine Providence. For Darwin, laws of nature were neither timeless nor conventional, but hypotheses that explained broad ranges of data. Even more importantly, Darwin attempted to frame a radically new form of hypothesis - one which emphasized not the nature of things, but how it was that natural things got to be the way they are. Philosophy, for Darwin, was not the study of natures - whether Platonic, Aristotelian or Baconian Forms, or the equations for 'vis viva'-but a natural study of changes and permanences. Furthermore, Darwin attempted always to frame his meta- physical questions naturalistically, thereby avoiding a large amount of the obscurity often associated with philosophies of process and change. In this essay I attempt to outline Darwin's theoretical position in enough depth to illustrate his philosophical views, to demonstrate his position in the history of the metaphysics of modern science. Before the 1800's physical science had opposed the older, teleological metaphysics by developing mechan- istic laws of nature. Yet the new metaphysicians retained significant portions of the older views (Burtt, 1932: 24-28; Koyrr, 1957: 273-276). Therefore, physical science's philosophy of mechanism did not suffice to refute Design and Tele- ology in general. The scientific metaphysics, by retaining the emphasis on 'natures' found itself not at all incompatible with Design - a circumstance recognized quite early by Spinoza. Darwin's more radical rejection of Design involved making previously metaphysical questions susceptible to naturalistic 204 EDWARD S. REED test. Where Laplace 'did not need' the hypothesis of God's Design, Darwin actually tried to refute it! 'Naturally, the metaphysician who desires to read some kind of plan or design into nature may argue that inefficiency' which Darwin had demonstrated, 'does not contradict efficiency ... but such argu- ments can serve to establish anything, and as Darwin showed, if one accepts them there are no grounds for rejecting arguments which lead to the opposite conclusion' (Ghiselin, 1969: 158). For Darwin, the argument from design was an hypothesis like any other hypothesis, and thus implied a set of testable conjectures about the world - including the Newtonian conjecture that the world is God's machine. Darwin's tests of these conjectures, he felt, refuted them: Paley's 'work of God', the human hand, is a rather inefficient contrap- tion, demonstrating not mechanical design so much as the historic episodes of vertebrate limbs. After satisfying himself that the hypothesis of design was refuted, Darwin tested his own hypothesis for the explanation of change in nature, Natural Selection, and seemed to corroborate most of his conjectures. The initial testing took place in the late 1830's and Darwin spent the last forty years of his life modifying and developing those laws of change by which he hoped to explain our world. II.