The overarching objective of the original article was to apply a well-defined set of measures in a systematic and objective way to evaluate the extent of scientific progress within a given research program. The measures chosen were identified and defined by major philosophers of science. These measures were then applied to the empirical studies on the diffusion of war. Starr and Siverson claim to find problems in my analysis that undermined the conclusions I reach. This reply argues that each of their claims is unfounded. Moreover, they fail to refute the conclusion that the marginal progressiveness of their program is a significant reason for reduced interest in this topic.