Alex Rosenberg

In The Structure of Biological Science I argued that the theory of natural selection is a statistical theory for reasons much like those which makes thermodynamics a statistical theory. In particular, the theory claims that fitness differences are large enough and the life span of species long enough for increases in average fitness always to appear in the long run; and this claim, I held, is of the same form as the statistical version of the second law of thermodynamics.For the latter law also makes a claim about the long run, and its statistical character is due to this claim: thermodynamic systems must in the long run approach an equilibrium level of organization that maximizes entropy. Over finite times, given local boundary conditions, an isolated mechanical system, like the molecules in a container of gas, may sometimes interact so as to move the entropy of the system further from, instead of closer to the equilbrium level. But given enough interacting bodies, and enough time, the system will always eventually move in the direction prescribed by the law. Thus, we can attach much higher probabilities to the prediction that non-equilibrium systems will reflect greater entropy in future periods than we can to predictions that they will move in the opposite direction. And as we increase the amount of time and the number of bodies interacting, the strength of the probability we can attach to the prediction becomes greater and greater.

Rosenberg applies current thinking in philosophy of science to neoclassical economics in order to assess its claims to scientific standing. Although philosophers have used history and psychology as paradigms for the examination of social science, there is good reason to believe that economics is a more appropriate subject for analysis: it is the most systematized and quantified of the social sciences; its practitioners have reached a measure of consensus on important aspects of their subject; and it encompasses a large number of apparently law-like propositions.

For Sober and Wilson, the key to group selection is the persistence of within-group behaviours that are individually altruistic -- the so-called ‘primary behaviours'. In the absence of kin-relatedness, such primary behaviours will render the group liable to invasion by non-cooperative strategies unless ‘secondary behaviours’ are in place. Secondary behaviour must in effect make the costs of deviation from the primary altruistic behaviour greater than the benefits of deviation. The secondary behaviour in effect enforces the primary behaviour. Secondary behaviour is also behaviour which is altruistic from the point of view of the individual, whenever enforcement has some costs and lower benefits to the enforcer. Enforcement always has some cost, when imposed. However, it increases the rate of cooperative primary behaviour and so has benefits for the group as a whole, whence its status as altruistic. When altruism and enforcement both emerge, altruism is amplified

Sober 2011 argues that, contrary to Hume, some causal statements can be known a priori to be true—notably, some ‘would promote’ statements figuring in causal models of natural selection. We find Sober's argument unconvincing. We regard the Humean thesis as denying that causal explanations contain any a priori knowable statements specifying certain features of events to be causally relevant. We argue that not every ‘would promote’ statement is genuinely causal, and we suggest that Sober has not shown that his examples of ‘would promote’ statements manage to achieve a priori status without sacrificing their causal character.

This review of recent work in the philosophy of science motivated by a commitment to 'naturalism' begins by identifying three key axioms and one theorem shared by philosophers thus self-styled. Owing much to Quine and Ernest Nagel, these philosophers of science share a common agenda with naturalists elsewhere in philosophy. But they have disagreed among themselves about how the axioms and the theorems they share settle long-standing disputes in the philosophy of science. After expounding these disagreements in the work of Boyd, Giere, Laudan, and Kitcher, I argue that naturalism needs to look for more than mere consistency in its foundations

In several places we have argued that ‘fitness’ is a primitive term with respect to the theory of evolution properly understood. These arguments have relied heavily on the axiomatization of the theory provided by one of us. In contrast, both John Beatty and Robert Brandon have separately argued for a “propensity“ interpretation of “fitness” ; and in Brandon and Beatty they attack our view that “fitness“ is a primitive term in evolutionary theory, concluding that a definition by way of propensities is possible and preferable. Here we reply to their criticisms, and argue that, at most, the view that fitness is a statistical propensity is a terminological variant on our thesis that it is a primitive in evolutionary theory.