For William Whewell and, later, Charles Peirce, the methods of science merited scientific examination themselves. Looking to history to build an inductive account of the scientific process, both men transformed scientific methods into scientific evidence. What resulted was a peculiar instance of what Ian Hacking calls “the looping effects of human kinds,” in which classifying human behavior changes that behavior. In the cases of Whewell and Peirce, the behavior in question was their own: namely, scientific study. This essay brings Hacking’s (...) formulation to bear on the status of science in nineteenth-century intellectual history, revealing the continued entanglement of science and philosophy even as they were being prized apart. Focusing on how Whewell and Peirce turned themselves into “scientific kinds,” the essay reveals the slippage between “what” and “how” across what Peirce once called “the age of methods.”. (shrink)