Published online by Cambridge University Press: 01 January 2022
I introduce two new tools in experimental neurobiology, optogenetics and DREADDs (designer receptors exclusively activated by designer drugs). These tools permit unprecedented control over activity in specific neurons in behaving animals. In addition to their inherent scientific interest, these tools make an important contribution to philosophy of science. They illustrate the very premises of Ian Hacking’s “microscope” argument for the relative independence of experiment from theory. This new example is important for generalizing Hacking’s argument because the background sciences (optics for microscopes, molecular biology for optogenetics, and DREADDs) and the fields of engineering producing these tools differ significantly.