Causal Concepts in Biology: How Pathways Differ from Mechanisms and Why It Matters

Abstract

Over the last two decades few topics in philosophy of science have received as much attention as mechanistic explanation. A significant motivation for these accounts is that scientists frequently use the term ‘mechanism’ in their explanations of biological phenomena. Of course, biologists use a variety of causal concepts in their explanations, including concepts like pathways, cascades, triggers, and processes. Despite this variety, mainstream philosophical views interpret all of these concepts with the single notion of mechanism. In using the mechanism concept interchangeably with other causal concepts, it is not clear that these accounts well capture the diversity of causal structures in biology. This article analyses two causal concepts in biology—the notions of ‘mechanism’ and ‘pathway’—and how they figure in biological explanation. I argue that these concepts have unique features, that they are associated with distinct strategies of causal investigation, and that they figure in importantly different types of explanation.