Discussions of the foundations of Classical Equilibrium Statistical Mechanics (SM) typically focus on the problem of justifying the use of a certain probability measure (the microcanonical measure) to compute average values of certain functions. One would like to be able to explain why the equilibrium behavior of a wide variety of distinct systems (different sorts of molecules interacting with different potentials) can be described by the same averaging procedure. A standard approach is to appeal to ergodic theory to justify this choice of measure. A different approach, eschewing ergodicity, was initiated by A. I. Khinchin. Both explanatory programs have been subjected to severe criticisms. This paper argues that the Khinchin type program deserves further attention in light of relatively recent results in understanding the physics of universal behavior.

The question of the influence of genes on behavior raises difficult philosophical and social issues. In this paper I delineate what I call the Developmentalist Challenge (DC) to assertions of genetic influence on behavior, and then examine the DC through an indepth analysis of the behavioral genetics of the nematode, C. elegans, with some briefer references to work on Drosophila. I argue that eight “rules” relating genes and behavior through environmentally-influenced and tangled neural nets capture the results of developmental and behavioral studies on the nematode. Some elements of the DC are found to be sound and others are criticized. The essay concludes by examining the relations of this study to Kitcher's antireductionist arguments and Bechtel and Richardson's decomposition and localization heuristics. Some implications for human behavioral genetics are also briefly considered.

Kenneth C. Schaffner's paper is an important contribution to the literature on behavioral genetics and on genetics in general. Schaffner has a long record of injecting real molecular biology into philosophical discussions of genetics. His treatments of the reduction of Mendelian to molecular genetics (Schaffner 1967, 1969) first drew philosophical attention to the problems of detail that have fuelled both anti-reductionism (Hull 1974, Kitcher 1984) and more sophisticated models of theory reduction (Sarkar 1992, Schaffner 1993). An injection of molecular detail into discussions of genetics is particularly necessary at the present time, when so many philosophers seem happy to discuss the philosophical and ethical implications of molecular biology using gene concepts derived from evolutionary biology (i.e., the ‘evolutionary gene concept’ of G.C Williams (Williams 1966, Dawkins 1982)). Schaffner has long advocated the view that the philosophy of biology should be more than the philosophy of evolution. This paper shows how radically a picture of gene action derived from molecular biology undercuts the popular picture associated with a more evolutionary view of genes as units of heredity or as ‘difference-makers’ mediated by the ‘black box’ of development (Sterelny and Kitcher 1988).

Although Caenorhabditis elegans was chosen and modified to be an organism that would facilitate a reductionist program for neurogenetics, recent research has provided evidence for properties that are emergent from the neurons. While neurogenetic advances have been made using C. elegans which may be useful in explaining human neurobiology, there are severe limitations on C. elegans to explain any significant human behavior.

The simple systems methodology is a powerful reductionistic research strategy. It has problems as implemented in developmental genetics because the organisms studied are few and unrepresentative. Stronger inferences require independent arguments that key traits are widely distributed phylogenetically. Evolutionary and developmental mechanisms of generative entrenchment and self-organization provide possible support, and are also necessary components of a developmental systems approach.

In this rejoinder to the three preceding comments, I provide some additional philosophical warrant for the biomedical sciences' focus on model organisms. I then relate the inquiries on model systems to the concept of ‘deep homology’, and indicate that the issues that appear to divide my commentators and myself are in part empirical ones. I cite recent work on model organisms, and especially C. elegans that supports my views. Finally, I briefly readdress some of the issues raised by Developmental Systems Theory.

1. Ramsey Sentences and the Function of Theoretical Concepts. In his famous paper “Theories,” Frank Ramsey (1931, 212–236; 1978, Ch. 4) introduced a technique of examining a scientific theory by means of certain propositions, dubbed later “Ramsey Sentences.” They are the results of what is often called Ramsey elimination. This prima facie elimination is often presented as a method of dispensing with theoretical concepts in scientific theorizing. The idea is this: Assume that we are given a finitely axiomatized scientific theory

where O1, O2, … are the primitive observation terms (individual constants, predicate constants, function constants, etc.) of (1) and H1, H2, … its primitive theoretical terms. For simplicity, it will be assumed that (1) is a first-order theory. Since it is finitely axiomatizable, we may think of it as having the form of a single complex proposition, i.e., the conjunction of all the axioms. What can then be done is to generalize existentially with respect to (1). The result is a sentence of the form

In (2), the theoretical terms H1, H2, … do not occur any longer. They have been replaced by the variables X1, X2, … bound to initial existential quantifiers. In this sense at least, Ramsey sentences do effect on elimination. Unlike (1), (2) is not a first-order sentence but a second-order one.

This paper is an empirical critique of causal accounts of scientific explanation. Drawing on explanations which rely on nonlinear dynamical modeling, I argue that the requirement of causal relevance is both too strong and too weak to be constitutive of scientific explanation. In addition, causal accounts obscure how the process of mathematical modeling produces explanatory information. I advance three arguments for the inadequacy of causal accounts. First, I argue that explanatorily relevant information is not always information about causes, even in cases where the explanandum has an identifiable causal history. Second, I argue that treating theoretical explanations as reductions from general causal laws does not accurately describe the types of “top-down” explanations typical of dynamical modeling. Finally, I argue that causal/mechanical accounts of explanation are intrinsically vulnerable to the irrelevance problem.

I criticize conceptual pluralism, as endorsed recently by John Dupré and Philip Kitcher, for failing to supply strategies for demarcating science from non-science. Using creation-science as a test case, I argue that pluralism blocks arguments that keep creation-science in check and that metaphysical pluralism offers it positive, metaphysical support. Logical empiricism, however, still provides useful resources to reconfigure and manage the problem of creation-science in those practical and political contexts where pluralism will fail.

This article considers the recent work of David Lewis, Ned Hall, and Michael Thau on chance and the best system account of law. My rejoinder suggests that, though their proposals may succeed at the stated goal of reworking the problematic relationship between chance, credence, and law, the resulting account of law suffers from an even more significant difficulty. To oversimplify a bit, I argue that their account is unable to handle the nomic necessity of laws. My criticisms suggest an alternative account of law which provides, I argue, a preferable account of nomic necessity.

Richard Healey (1997) argues that the Aharonov-Bohm effect demands the recognition of either nonlocal or nonseparable physics in much the way that violations of Bell's inequality do. A careful examination of the effect and the arguments, though, shows that Healey's interpretation of the Aharonov-Bohm effect depends critically on his interpretation of gauge theories, and that the analogy with violations of Bell's inequalities fails.