A MODERN SYNTHESIS OF PHILOSOPHY AND BIOLOGY Marion Godman Forthcoming in Kelly Becker & Ian Thomson (eds.), History of Philosophy, 1945 to 2015. Cambridge: Cambridge University Press. Biology was not of much concern to the logical empiricists, who settled for physics as their model of science and scientific explanation. In the course of the period of this volume, the situation has changed drastically. Philosophy of biology is now a large and respected academic specialisation in its own right. There is much to be said for the birth of philosophy of biology coming out of the Modern (Evolutionary) Synthesis (MS) during the 1930s, 40s the 1950s. While biologists, such as Theodosius Dobzhansky, Julian Huxley, George Simpson, and Ernst Mayr launched the MS, philosophers as interpreters and critics played a significant part in determining its faith, as we shall see. Moreover, as noted by Marjorie Grene and David Depew, “The work of defending, expanding, challenging, and, perhaps, replacing the Modern Synthesis has tended to bring out the philosopher in many evolutionary biologists” (2004, 248). So wherein lied the intellectual potency of the MS? One of the central points of the MS was to unify disciplines such as Mendelian genetics, palaeontology, systematics, biometrics and ecology. 1 In particular, the MS aimed to improve on the theoretical framework of Darwin’s evolution by fusing natural selection with Mendelian population genetics. Population genetics allows for studies of evolutionary change and changes in fitness, by studying changes in gene frequencies within populations. This change is thought to occur according to the degree of genetic variation within a population coupled with the degree of heritability of different genes (where heritability is a measure of resemblance between parents and offspring). The idea is then that natural selection is demonstrated by the relative speed and accuracy by which genes replicate. Success in reproduction is supposed to indicate the adaptive superiority of organisms with those genes leaving more offspring than others (see e.g. Brandon 1978). I will focus on three themes in the philosophy of biology where from the MS and onward there have been particularly high levels of cross-fertilization amongst philosophers and biologists. It is however worth mentioning some of what this focus omits. The domains of ecology and embryology, although envisioned as part of the MS by at least Huxley and Dobzhansky, have always had a bit of a strained relationship with evolutionary theorising, and the philosophy of ecology has also been rather autonomous in philosophy of biology (Levins 1968). Nowadays topics in immunology and synthetic biology, which would have been seen as peripheral earlier, are also receiving a great deal of philosophical scrutiny. Moreover, many 1 The MS preceded molecular genetics and the discovery of the molecular mechanism of inheritance empirically that was borne out by the uncovering the double-stranded DNA molecule using x-ray crystallography. Most now think molecular genetics enhances rather than replaces an evolutionary perspective.