There are two competing interpretations of the modern synthesis theory of evolution: the dynamical (also know as ‘traditional’) and the statistical. The dynamical interpretation maintains that explanations offered under the auspices of the modern synthesis theory articulate the causes of evolution. It interprets selection and drift as causes of population change. The statistical interpretation holds that modern synthesis explanations merely cite the statistical structure of populations. This paper offers a defense of statisticalism. It argues that a change in trait frequencies (...) in a population can be attributed only to selection or drift against the background of a particular statistical description of the population. The traditionalist supposition that selection and drift are description‐independent causes of population change leads the dynamical interpretation into a dilemma: it must face a contradiction or accept the loss of explanatory power. (shrink)

The thesis that natural selection explains the frequencies of traits in populations, but not why individual organisms have the traits tehy do, is here defended and elaborated. A general concept of ‘distributive explanation’ is discussed.

I have recently argued that origin essentialism regarding individual organisms entails that natural selection does not explain why individual organisms have the traits that they do. This paper defends this and related theses against Mohan Matthen's recent objections.

Does natural selection explain why individual organisms have the traits that they do? According to "the Negative View," natural selection does not explain why any individual organism has the traits that it does. According to "the Positive View," natural selection at least sometimes does explain why an individual organism has the traits that it does. In this paper, I argue that recent arguments for the Positive View fail in virtue of running afoul of the doctrine of origin essentialism and I (...) demonstrate that other recent defenses of the Negative View depend upon my own for their plausibility. (shrink)

argue that natural selection does not explain the genotypic arid phenotypic properties of individuals. On this view, natural selection explains the adaptedness of individuals, not by explaining why the individuals that exist have the adaptations they do, but rather by explaining why the individuals that exist are the ones with those adaptations. This paper argues that this ‘Negative’ view of natural selection ignores the fact that natural selection is a cumulative selection process. So understood, it explains how the genetic sequences (...) that individuals inherit and that are responsible for their complex (and co-adapted) adaptations first arose in the gene-pool. (shrink)

Two strong arguments have been given in favor of the claim that no selection process can play a role in explaining adaptations. According to the first argument, selection is a negative force; it may explain why the eliminated individuals are eliminated, but it does not explain why the ones that survived (or their offspring) have the traits they have. The second argument points out that the explanandum and the explanans are phenomena at different levels: selection is a population-level phenomenon, whereas (...) adaptation occurs on the individual level. Thus, selection can explain why individuals in a certain population have a certain trait, but it cannot explain why a certain indi- vidual has this trait. After pointing out that both arguments ignore the significance of the limitation of environmental resources, I will construe a positive argument for the claim that cumulative selection processes can, indeed, play a role in explaining adaptations. (shrink)

Sound like a philosopher’s controversy? I think so. In ‘Evolution,’ I argued that Anti-Individualism was committed to a ‘highly metaphysical’ proposition at odds with the methodology of population genetics. This infelicity gave me reason for rejecting it. In his recent article, Pust takes issue with Neander and me. Until Pust wrote, Sober felt some small pressure from Individualism, and had shifted, albeit microscopically, toward it—he thought that on a very broad conception of causation, there might be some reason to think (...) that selection explains individual traits. He is now convinced that he was right all along. So we are back where we were a few years ago, though with new arguments on each side. Such is the nature of progress in philosophy. The purpose of this paper is to offer some refinements of Individualism. (shrink)

It has been claimed that certain forms of individual essentialism render the Theory of Natural Selection unable to explain why any given individual has the traits it does. Here, three reasons are offered why the Theory ought to ignore these forms of essentialism. First, the trait-distributions explained by population genetics supervene on individual-level causal links, and thus selection must have individual-level effects. Second, even if there are individuals that possess thick essences, they lie outside the domain of the Theory. Finally, (...) the contingency of sexual reproduction suggests that essentialism is misguided in this arena. 1 The problem 2 A reprise of the controversy 3 Enter individual essences 4 How can selection not have individual-level effects? 5 Why can't we get rid of essences we don't like? 6 Is sex necessary? (shrink)

natural selection may show why all (most, some) humans have an opposable thumb, but cannot show why any particular human has one, Karen Neander ([1995a], [1995b]) argues that this is false because natural selection is 'cumulative'. It is argued here, on grounds independent of its cumulativity, that selection can explain the characteristics of individual organisms subsequent to the event. The difference of opinion between Sober and his critics turns on an ontological dispute about how organisms are identified and individuated. The (...) assumption that Sober needs to make his point is extraneous to population genetics, and, for this reason, gratuitous. (shrink)

argues that when reproduction is sexual, natural selection can explain why individual organisms possess the traits they do. In stating his argument Matthen makes use of a conception of individual organisms as receptacles for collections of genes—a conception that cannot do the work Matthen requires of it. Either these receptacles are abstract objects, such as bare possibilities for organisms, or they are concrete. The first reading is too weak, since it allows selection to explain individual traits in both sexual and (...) asexual contexts. The only concrete entities we might think of as receptacles for collections of genes are male or female gametes. It is true that in the sexual context selection explains why an individual gamete combines with a second gamete of one type rather than another; however, this is not to say that selection explains why an individual organism has the traits it does. (shrink)

Can selection explain why individuals have the traits they do? This question has generated significant controversy. I will argue that the debate encompasses two separable aspects, to detrimental effect: (1) the role of selection in explaining the origin and evolution of biological traits and (2) the implications this may have for explaining why individuals have the traits they do. (1) can be settled on the basis of evolutionary theory while (2) requires additional, extra-scientific assumptions. By making a distinction between traits (...) affected by a single factor and traits affected by multiple factors I show that selection can, under certain conditions, help explain the origin of traits. Resolving the first aspect enables us to critically assess the various incompatible and independent philosophical commitments made within the second aspect of the debate. (shrink)

How do fitness and natural selection relate to other evolutionary factors like architectural constraint, mode of reproduction, and drift? In one way of thinking, drawn from Newtonian dynamics, fitness is one force driving evolutionary change and added to other factors. In another, drawn from statistical thermodynamics, it is a statistical trend that manifests itself in natural selection histories. It is argued that the first model is incoherent, the second appropriate; a hierarchical realization model is proposed as a basis for a (...) statistical treatment. It emerges that natural selection does not cause evolution; it just is evolution. The theory incorporates relations of statistical correlation, but not the kind of causation found in fundamental physical processes. (shrink)