Homeostatic Property Cluster (HPC) theory suggests that species and other biological taxa consist of organisms that share certain similarities. HPC theory acknowledges the existence of Darwinian variation within biological taxa. The claim is that “homeostatic mechanisms” acting on the members of such taxa nonetheless ensure a significant cluster of similarities. The HPC theorist's focus on individual similarities is inadequate to account for stable polymorphism within taxa, and fails properly to capture their historical nature. A better approach is to treat distributions of traits in species populations as irreducible facts, explained in terms of selection pressures, genealogy, and other evolutionary factors. We call this view Population Structure Theory (PST). PST accommodates the view, implicit in biological systematics, that species are identified by reference to particular historical populations.

In this paper, I consider ways of responding to critiques of natural kinds monism recently suggested from the pluralist camp. Even if monism is determined to be untenable in certain domains (say, about species), it might well be tenable in others. Chemistry is suggested to be such a monist-friendly domain. Suggestions of trouble for chemical kinds can be defused by attending to the difference between monism as a metaphysical thesis and as a claim about classification systems. Finally, I consider enantiomers as a test case for the monism/pluralism debate. The question of whether enantiomers differ in kind does not appear easily answerable. I suggest that this legislates for pluralism in chemistry.

Physicalism and antireductionism are the ruling orthodoxy in the philosophy of biology. But these two theses are difficult to reconcile. Merely embracing an epistemic antireductionism will not suffice, as both reductionists and antireductionists accept that given our cognitive interests and limitations, non-molecular explanations may not be improved, corrected or grounded in molecular ones. Moreover, antireductionists themselves view their claim as a metaphysical or ontological one about the existence of facts molecular biology cannot identify, express or explain. However, this is tantamount to a rejection of physicalism and so causes the antireductionist discomfort. In this paper we argue that vindicating physicalism requires a physicalistic account of the principle of natural selection, and we provide such an account. The most important payoff to the account is that it provides for the very sort of autonomy from the physical that antireductionists need without threatening their commitment to physicalism.

In seeking to explain the evolution of social cooperation, many scholars are using increasingly complex game-theoretic models. These complexities often model readily observable features of human and animal populations. In the case of previous games analyzed in the literature, these modifications have had radical effects on the stability and efficiency properties of the models. We will analyze the effect of adding spatial structure to two communication games: the Lewis Sender-Receiver game and a modified Stag Hunt game. For the Stag Hunt, we find that the results depart strikingly from previous models. In all cases, the departures increase the explanatory value of the models for social phenomena.

We introduce a dynamic model for evolutionary games played on a network where strategy changes are correlated according to degree of influence between players. Unlike the notion of stochastic stability (Foster and Young, 1990), which assumes mutations are stochastically independent and identically distributed, our framework allows for the possibility that agents correlate their strategies with the strategies of those they trust, or those who have influence over them. We show that the dynamical properties of evolutionary games, where such influence neighborhoods appear, differ dramatically from those where all mutations are stochastically independent, and establish some elementary convergence results relevant for the evolution of social institutions.

This paper tries to get a grip on two seemingly conflicting intuitions about reductionism in quantum mechanics. On one hand it is received wisdom that quantum mechanics puts an end to ‘reductionism’. Quantum entanglement is responsible for such features of quantum mechanics as holism, the failure of supervenience, and emergence. While I agree with these claims, I will argue that it is only part of the story. Quantum mechanics provides us with thoroughgoing reductionist explanations. I will distinguish two kinds of microexplanation (or micro-‘reduction’). I will argue that even though quantum entanglement provides an example of the failure of one kind of microexplanation, it does not affect the other. Contrary to a recent paper by Kronz and Tiehen, I claim that the explanation of the dynamics of quantum mechanical systems is just as reductionist as it used to be in classical mechanics.

Batterman has recently argued that fundamental theories are typically explanatorily inadequate, in that there exist physical phenomena whose explanation requires that the conceptual apparatus of a fundamental theory be supplemented by that of a less fundamental theory. This paper is an extended critical commentary on that argument: situating its importance, describing its structure, and developing a line of objection to it. The objection is that in the examples Batterman considers, the mathematics of the less fundamental theory is definable in terms of the mathematics of the fundamental theory, and that only the latter need be given a physical interpretation—so we can view the desired explanation as drawing only upon resources internal to the more fundamental physical theory.

I respond to Belot's argument and defend the view that sometimes ‘fundamental theories’ are explanatorily inadequate and need to be supplemented with certain aspects of less fundamental ‘theories emeritus’.

The paper is based on ranking theory, a theory of degrees of disbelief (and hence belief). On this basis, it explains enumerative induction, the confirmation of a law by its positive instances, which may, indeed, take various schemes. It gives a ranking theoretic explication of a possible law or a nomological hypothesis. It proves, then, that such schemes of enumerative induction uniquely correspond to mixtures of such nomological hypotheses. Thus, it shows both that de Finetti's probabilistic representation theorems may be transformed into an account of confirmation of possible laws and that enumerative induction is equivalent to such an account. The paper concludes with some remarks about the apriority of lawfulness, or the uniformity of nature.

In a recent essay, John Norton proposes a material theory of induction, according to which all justification for inductive inference ultimately stems from the particular facts of the case at hand. Despite being sympathetic to the pluralistic spirit of this proposal, I argue that central controversies among leading theories of inductive inference turn not on material facts but upon normative judgments regarding the proper standards and aims of induction. Thus, a pluralistic approach to induction can be successfully developed only given an explanation of how the choice of such aims and standards depends on features of particular cases.

In his discussion of “Scientific Explanation and the Sense of Understanding” (Trout 2002), de Regt (2004) argues that Trout “denounces understanding as irrelevant, if not dangerous, from an epistemic perspective…” (de Regt 2004, 98), and that Trout prefers “a thoroughly objectivist view, in which understanding has no epistemic function and explanations require only accurate theories” (100). I argue that this is a fundamental misinterpretation of the objectivist proposal of Trout (2002), and that it results from de Regt's failure to address the distinction announced there between genuine and counterfeit understanding. De Regt also advances a pragmatic alternative to my realist account of understanding in scientific explanation, one that focuses on the skills of scientists and the intelligibility of theories. After supplementing my earlier account of genuine understanding, I argue that de Regt's pragmatic account obscures the nature of scientific explanation, and is vulnerable on several additional fronts.

David Lewis (1979) defends the thesis of the asymmetry of overdetermination: later affairs are seldom overdetermined by earlier affairs, but earlier affairs are usually overdetermined by later affairs. Recently, Carol Cleland (2002) has argued that since the distinctive methodologies of historical science and experimental science exploit different aspects of this asymmetry, the methodology of historical science is just as good, epistemically speaking, as that of experimental science. This paper shows, first, that Cleland's epistemological conclusion does not follow from the thesis of the asymmetry of overdetermination, because overdetermination (in Lewis's sense) is compatible with epistemic underdetermination. The paper also shows, contra Cleland, that there is at least one interesting sense in which historical science is epistemically inferior to experimental science, after all, because local underdetermination problems are more widespread in historical than in experimental science.

There is a very plausible transitivity principle for theory choice. It says that if all criteria of theory evaluation are considered, and theory A is a better theory than theory B, and theory B is a better theory than theory C, then A is a better theory than C. I argue against this principle. It turns out that whenever there are two or more relevant and independent criteria of theory evaluation, and that whenever at least of one the criteria is ‘nonlinear’ in a certain sense, there may be violations of transitivity that do not violate any standards of rationality (of theory choice). This shows, again, that theory choice cannot be seen as merely the application of given rules of rational theory choice.

Faced with the paradox of undermining futures, Humeans have resigned themselves to accounts of chance that severely conflict with our intuitions. However, such resignation is premature: The problem is Humean Supervenience (HS), not Humeanism. This paper develops a projectivist Humeanism on which chance claims are understood as normative, rather than fact stating. Rationality constraints on the cotenability of norms and factual claims ground a factual-normative worlds semantics that, in addition to solving the Frege-Geach problem, delivers the intuitive set of possibilia for each chance law. Hence, the account does not entail HS, and the paradox does not arise. A confirmation theory is developed, and the Principal Principle is justified.

Scientists typically use a variety of representations, including different kinds of figures, to present and defend hypotheses. In order to understand the justification of scientific hypotheses, it is essential to understand how visual representations contribute to scientific arguments. Since the logical understanding of arguments involves the truth or falsity of the representations involved, visual representations must have the capacity to bear truth in order to be genuine components of arguments. By drawing on Goodman's analysis of symbol systems, and on Tarski's work on truth, I show that the figures used in science meet this criterion.