The purpose of this work is twofold: to explain some of the limitations affecting
traditional approaches to theory success, and to outline a criterion for the comparative
evaluation of a theory’s empirical success. Empirical adequacy, predictive power,
specification of causal mechanisms, and explanatory unification are here regarded as the
main, not mutually exclusive kinds of theory success. From that basis, the traditional
quantitative criterion for theory success -mainly revolving around the number of a
theory’s true empirical consequences-, is refined by adding some key qualitative
requirements specially focused on issues regarding a theory’s scope, predictive power,
and possible adhocness. A special emphasis will be placed on the following issues: a)
the superiority of prediction over accommodation (Lipton 1991/2004, Foster 2002), b)
the resolution of non-refuting anomalies (Laudan 2000, Kuipers 2005), and c) the
limited use of ad hoc hypotheses (Thagard 1978, Leplin 1975).
