 The history of molecular biology is in part the history of experimental techniques designed to probe the macromolecular mechanisms found in living things. Philosophers in turn have looked to molecular biology as a case study for understanding how experimentation works in science—how it contributes to scientific discovery, distinguishes correlation from causal and constitutive relevance, and decides between competing hypotheses (Barwich and Baschir 2017). In all three cases, the concept of a mechanism is central to understanding the function of experimentation in molecular biology (also see the entry on experimentation in biology).