Darwin and the Nature of Species

8. Darwin’s Strategy

153 Chapter 8 Darwin’s Strategy If the previous analysis is basically correct, it raises the obvious question of why Darwin would define “species” nominalistically, both taxa and category . If he was indeed a realist, it seems extremely odd that he would do this, especially since it is duplicitous and he was, after all, a man of honor. In this chapter I will develop and defend a novel answer to this problem. Since Darwin, as far as is known, never provided an explicit answer to this question, and since it is obviously too late to get inside his head in the manner of a Schilpp volume, the best that we can do, once again, is to apply the principle of charity and make the best of the evidence that we can. I believe that the answer I develop has considerable evidence in its support. But first I want to look at the answers given by Ghiselin, Mayr, Beatty, Sulloway, Hodge, McOuat, and my former self. The failings of their answers will further justify the search for a new solution. Ghiselin (1969), as we have seen in chapter 2, argued that Darwin was a species taxa realist, going as far as to characterize him as a precursor of the species-as-individuals view. When it came to the species category, however, Ghiselin characterized Darwin as a nominalist. Ghiselin’s justification for this conclusion hinges on his claim that Darwin had an Aristotelian concept of category, a concept characterized by strict essentialism.1 Since varieties, in Darwin’s view, gradually evolve into species if they do not first go extinct, then contrary to the creationists there cannot be an essential distinction between species and varieties. So this is why the term “species” cannot on Darwin’s view be defined. As Ghiselin (1969) put it, Darwin “insisted on Aristotelian definition as a criterion of reality or naturalness . To Darwin, as to many other taxonomists, an inability to give rigorous definitions for the names of taxonomic groups led to a belief that somehow such assemblages were artificial” (82). Ghiselin claims further that Darwin “maintained that there are no ‘essential’ differences between species and varieties, and that both terms designate the same basic kind of entity.” Thus, says Ghiselin, “Darwin was denying the reality, not of taxa, but of categories” (93). There are a number of problems with this view. First, as we have seen, Darwin did not think that species and varieties are basically the same kind of entity. Although they have a lot in common in Darwin’s view, from the perspective of the horizontal dimension (and that as we have seen is the dimension for Darwin in which species have their primary reality) there is a fundamental distinction, most notably natural selection and the fixity of adaptations. Second, there is no reason to believe that Darwin subscribed to Aristotelian essentialism, with the corresponding concept of definition (genos and differentiae), as “a criterion of reality or naturalness.” For a start, Darwin never read Aristotle (cf. Burkhardt and Smith 1988, 498 n. 9). If he subscribed to Aristotelian essentialism for the reality of categories, then, his knowledge of Aristotle must have been secondhand. This knowledge was, of course, part of the worldview that Darwin inherited. Roughly a century before Darwin’s Beagle voyage, Linnaeus wedded the Aristotelian paradigm to Christian creationism. This would be the received view for over the next hundred years (Stamos 2005). It was a view, as we have seen in chapter 1, that involved essentialism for membership in categories and bridgeless gaps between those categories, conceptualized as boxes, with accidental (nonessential) characters being irrelevant. Although Darwin had indeed read Linnaeus, and of course the latter’s worldview was (roughly speaking) the established view among Darwin’s scientific contemporaries, at least for species, there is nevertheless nowhere in Darwin’s writings where he explicitly subscribes to Aristotelian or Linnean criteria for the reality of categories. Granted, he makes statements which could be interpreted in that way. For example, in Natural Selection he says “it is no wonder that there should be difficulty in defining the difference between a species & a variety;—there being no essential, only an arbitrary difference” (Stauffer 1975, 98). Moreover, as we have seen earlier, near the end of the Origin he says “we shall at least be freed from the vain search for the undiscovered and undiscoverable essence of the term species” 154 DARWIN AND THE NATURE OF SPECIES [18.118.254.94] Project MUSE (2024-04-26...