Forty Years of ‘The Strategy’: Levins on Model Building and Idealization

Abstract

Abstract.This paper is an interpretation and defense of Richard Levins' "The Strategy of Model Building in Population Biology." Levins "The Strategy" has been extremely influential among biologists since its publication forty years ago. In this influential article, Levins confronts some of the deepest philosophical issues surrounding modeling and theory construction. By way of interpretation, I will discuss each of Levins' major philosophical themes: the problem of complexity, the existence and consequence of tradeoffs, and robustness analysis. I will argue that Levins' article is concerned, at its core, with justifying the use of multiple, idealized models in population biology.Keywords: Richard Levins, tradeoffs, models, model building, idealization, robustness, population biology, theoretical ecology, complex systems Richard Levins' article "The Strategy of Model Building in Population Biology" is one of the most influential philosophical discussions about theory construction. It is frequently cited by population biologists and while less known among philosophers of science, it was was in included in the first edition of Elliott Sober's widely used philosophy of biology anthology. (Sober, 1984) Levins article contains enormous insight into some of the deepest philosophical issues surrounding modeling and theory construction. His focus on the practice of modeling, rather than on the outcome of mature theorizing, revealed important aspects of the enterprise that had not previously been appreciated. For example, he called attention to the tradeoffs one faces when constructing and analyzing models. He also thoughtfully discussed different strategies for constructing models, the complex ways that one gathers confirming evidence for these models, and the pitfalls associated with aiming for complete representations at the expense of all other considerations.Despite the importance of Levins' article, it has received very little critical attention by philosophers of science. Notable exceptions include articles by William Wimsatt (1987Wimsatt ( , 1981 and a joint article by Stephen Orzack and Elliott Sober (1993). Within the last few years, several discussions of Levins' article and related methodological discussions have started to appear (Odenbaugh, ms; Weisberg, 2004; Weisberg, forthcoming-a) and a conference has been devoted to "The Strategy of Model Building" and Levins' methodological work, from which many of the papers in this issue of Biology and Philosophy are drawn.

The Volterra Principle Generalized

“…In reaction to Orzack's and Sober's objection, Levins (1993) argues that he did not intend robustness analysis to provide nonempirical 6. See Weisberg (2006a) for an appraisal of Levins's paper.…”

“…Weisberg and Reisman. The most influential recent account of robustness analysis has been proposed by Weisberg (2006b). 7 Weisberg aims to reconcile robustness analysis with the objections raised by Orzack and Sober.…”

“…Weisberg and Reisman then argue that the Volterra Principle is robust according to all three kinds of robustness. They provide a formulation of the Volterra Principle that modifies the "hypothesis" from Weisberg (2006b). The new formulation is based on the notions of negative coupling and biocide.…”

“…Does this mean that the Volterra Principle is questionable as well? Weisberg (2006b), and Weisberg and Reisman (2008) argue that this is not the case. They propose that the Volterra Principle can also be established from other predator-prey models.…”

“…5 Does this mean that the Volterra Principle is also doomed to fail? This question has been brought to philosophers' attention in two papers (Weisberg 2006b;Weisberg and Reisman 2008). Weisberg and Reisman argue that the Volterra Principle does not de-5.…”