 Take discovery. Throughout much of the twentieth century, philosophers of science treated scientific discovery as if it were off-limits to philosophical analysis; philosophers could evaluate the rational process of confirmation, the argument went, but the psychological process of discovery (the “aha!” moment) fell into the realm of creativity (Popper 1965; see the entry on  scientific discovery).  Darden has countered with a focus on the strategies that scientists employ to construct, evaluate, and revise mechanical explanations of phenomena; on her view, discovery is a piecemeal, incremental, and iterative process of mechanism elucidation. In the 1950s and 1960s, for example, scientists from both molecular biology and biochemistry employed their own experimental strategies to elucidate the mechanisms of protein synthesis that linked DNA to the production of proteins. Molecular biologists moved forward from DNA using experimental techniques such as x-ray crystallography and model building to understand how the structure of DNA dictated what molecules it could interact with; biochemists simultaneously moved backward from the protein products using in vitro experimental systems to understand the chemical reactions and chemical bonding necessary to build a protein. They met in the middle at RNA, ultimately leading to Watson’s famous mechanism schema DNA → RNA → protein. Far from being philosophically inscrutable, Darden points out that the molecular biologists were “forward chaining” while the biochemists were “backward chaining”, using information about the working entities and activities that they knew about to infer what could come next or before in the mechanism of protein synthesis (Darden 2006a: chapters 3, 12; Craver and Darden 2013: chapter 10).