 Being able to successfully take a disease as complex as sickle cell anemia or Parkinson’s and reduce it to a single genetic error that cascades through various systems, even if that reduction holds for only a proper subset of cases, illustrates that reduction can be a powerful tool for research and explanation in medicine. It cannot be the only tool in the toolkit, since some diseases or dysfunctions may be only partially reducible, or for which only some cases are reducible. But it is a good working assumption, as Oppenheim and Putnam put it, in tackling a problem with an unknown etiology, to look for ways to reduce it to a few or even a single causal driver at a molecular level (Andersen 2016: 86).