Published online by Cambridge University Press: 01 April 2022
While many philosophers of science have accorded special evidential significance to tests whose results are “novel facts”, there continues to be disagreement over both the definition of novelty and why it should matter. The view of novelty favored by Giere, Lakatos, Worrall and many others is that of use-novelty: An accordance between evidence e and hypothesis h provides a genuine test of h only if e is not used in h's construction. I argue that what lies behind the intuition that novelty matters is the deeper intuition that severe tests matter. I set out a criterion of severity akin to the notion of a test's power in Neyman-Pearson statistics. I argue that tests which are use-novel may fail to be severe, and tests that are severe may fail to be use-novel. I discuss the 1919 eclipse data as a severe test of Einstein's law of gravity.
The research for this paper took place during tenure of a National Endowment for the Humanities Summer Stipend Fellowship and a National Endowment for the Humanities Fellowship for College Teachers. I gratefully acknowledge that support. Numerous stimulating discussions with Alan Musgrave were integral to formulating the ideas in this paper. I owe special thanks to George Barnard for insights into the statistical analysis of the 1919 eclipse data. For their valuable comments and criticism, I thank Dick Burian, Stephen Brush, Ronald Giere, Marjorie Grene, Larry Laudan, Ronald Laymon, Isaac Levi, Harlan Miller, Karl Popper, J. D. Trout, and John Worrall. Revisions were carried out while visiting the Center for Philosophy of Science at the University of Pittsburgh. I am grateful for the Center's stimulating environment, and for immensely helpful discussions on this paper with John Earman, Clark Glymour, Adolf Grünbaum, and Wesley Salmon. Versions of this paper have been given at the University of Hawaii, University of Maryland, and University of Pittsburgh.