The Nature of Evolutionary Biology: At the Borderlands Between Historical and Experimental Science

Abstract

For some time now, both biologists and philosophers of science have been struggling with the nature of evolutionary biology as a discipline. On the one hand, and dating back to Ronald Fisher’s fundamental theorem of natural selection, the claim is that evolutionary biology is a predictive science based on rigorous mathematical foundations—indeed, Fisher consciously styled his theorem after the second principle of thermodynamics in physics, the (presumed) queen of sciences. On the other hand, Fisher’s historical antagonist, Sewall Wright, emphasized the role of chance events (random drift) in countering and sometimes thwarting natural selection. The debate became central to Stephen Gould’s attempt in the 1980s to establish paleontology, the quintessential historical science within biology, as a “nomothetic” (i.e., aiming at the discovery of general laws) enterprise, while at the same time acknowledging the macroevolutionary import of chance events like the asteroidal impact that caused the extinction of so many species at the end of the Cretaceous. In this chapter I will deploy a novel philosophical analysis by Carol Cleland and examine recent experimental results on the replicability of evolutionary trajectories, to clarify the status of evolutionary biology as a discipline and that of the relative role of what Jacques Monod referred to as chance and necessity in biological explanations.