This is a comment on the paper by Barnes and the responses from Scerri and Worrall, debating the thesis that a fact successfully predicted by a theory is stronger evidence than a similar fact known before the prediction was made. Since Barnes and Scerri both use evidence presented in my paper on Mendeleev’s periodic law to support their views, I reiterate my own position on predictivism. I do not argue for or against predictivism in the normative sense that philosophers of (...) science employ, rather I describe how scientists themselves use facts and predictions to support their theories. I find wide variations, and no support for the assumption that scientists use a single ‘Scientific Method’ in deciding whether to accept a proposed new theory.Keywords: Predictivism; Novel predictions; Accommodation; Periodic law; Periodic table; Dmitri Mendeleev. (shrink)

In The Paradox of Predictivism I tried to demonstrate that there is an intimate relationship between predictivism and epistemic pluralism. Here I respond to various published criticisms of some of the key points from Paradox from David Harker, Jarret Leplin, and Clark Glymour. Foci include my account of predictive novelty, the claim that predictivism has two roots, the prediction per se and predictive success, and my account of why Mendeleev’s predictions carried special weight in confirming the Periodic Law of the (...) Elements. (shrink)