Susan Mills and John Beatty proposed a propensity interpretation of fitness (1979) to show that Darwinian explanations are not circular, but they did not address the critics' chief complaint that the principle of the survival of the fittest is either tautological or untestable. I show that the propensity interpretation cannot rescue the principle from the critics' charges. The critics, however, incorrectly assume that there is nothing more to Darwin's theory than the survival of the fittest. While Darwinians all scoff at (...) this assumption, they do not agree about what role, if any, this principle plays in Darwin's theory of natural selection. I argue that the principle has no place in Darwin's theory. His theory does include the idea that some organisms are fitter than others. But greater reproductive success is simply inferred from higher fitness. There is no reason to embody this inference in the form of a special principle of the survival of the fittest. (shrink)

Given the amount of literature devoted to the reasoning used in Darwin’s Origin of Species, an interpretation seeking to revise the standard take on Darwin’s methodology is unexpected. Yet,, and challenges the view that Darwin drew an analogy in the Origin on the grounds that such a strategy could not support the possibility of a new species emerging. I suggest, however, that how one interprets causal efficacy is intimately connected with Darwin’s use of analogy. A more robust conception of natural (...) selection, as found in the Origin, supports the standard interpretation, significantly weakening Richards’ charge of a paradox. (shrink)

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The analogy Darwin drew between artificial and natural selection in "On the Origin of Species" has a detailed structure that has not been appreciated. In Darwin’s analogy, the kind of artificial selection called Methodical selection is analogous to the principle of divergence in nature, and the kind of artificial selection called Unconscious selection is analogous to the principle of extinction in nature. This paper argues that it is the analogy between these two different principles familiar from his studies of artificial (...) selection and the two different principles he claims are operative in nature that provides the main structure and force of the analogy he uses to make his case for the power of natural selection to produce new species. Darwin’s statements explicitly distinguishing between these two kinds of principles at work in nature occur prominently in the text of the Origin. The paper also shows that a recent revisionist claim that Darwin did not appeal to the efficacy of artificial selection is mistaken. (shrink)

The paper characterizes Darwin's theory, providing a synthesis of recent historical investigations in this area. Darwin's reading of Malthus led him to appreciate the importance of population pressures, and subsequently of natural selection, with the help of the wedge metaphor. But, in itself, natural selection did not furnish an adequate account of the origin of species, for which a principle of divergence was needed. Initially, Darwin attributed this to geographical isolation, but later, following his work on barnacles which underscored the (...) significance of variation, and arising from his work on botanical arithmetic, he supposed that diversity allowed more places to be occupied in a given region. So isolation was not regarded as essential. Large regions with intense competition, and with ample variation spread by blending, would facilitate speciation. The notion of place was different from niche, and it is questioned whether Darwin's views on ecology were as modern as is commonly supposed. Two notions of struggle are found in Darwin's theory; and three notions of variation. Criticisms of his theory led him to emphasize the importance of variation over a range of forms. Hence the theory was populational rather than typological. The theory required a Lamarckian notion of inheritable changes initiated by the environment as a source of variation. Also, Darwin deployed a use/habit theory; and the notion of sexual selection. Selection normally acted at the level of the individual, though kin selection was possible. Group selection was hinted at for man. Darwin's thinking (and also the exposition of his theory) was generally guided by the domestic-organism analogy, which satisfied his methodological requirement of a vera causa principle. (shrink)

While the struggle for life played an important role in the process of natural selection as it was conceived by Darwin, natural selection is commonly characterized today as a process which does not necessarily involve struggle. Nevertheless, there have been some attempts to show the importance of struggle to the process of natural selection. The present paper aims to continue these attempts and clarify the precise evolutionary role of struggle. The paper focuses on a recent dispute regarding the role of (...) struggle between Peter Godfrey-Smith and Tim Lewens. Godfrey-Smith argues that struggle makes populations into "paradigm cases of Darwinian populations", meaning that struggle leads natural selection to produce adaptations. Lewens, in contrast, argues that Godfrey-Smith's argument fails to show that struggle plays such a role. I argue that Godfrey-Smith's argument that struggle leads selection to produce adaptations can be understood in two different ways. Lewens interprets Godfrey-Smith's argument in one of these ways, and rightly argues that thus understood, this argument fails to show that struggle leads selection to produce adaptations. However, I show that understood in a second way, Godfrey-Smith's argument does show that struggle plays such a role. Still, I show that there is an additional problem with Godfrey-Smith's argument that struggle makes populations into "paradigm cases of Darwinian populations". It does not capture the precise role played by struggle in the relation between selection and adaptation. Thus, the present paper clarifies the unique role that struggle plays in the relation between selection and adaptation in evolutionary theory. (shrink)