I challenge Hacking's characterization of Kuhn's constructionism. I argue that Kuhn does not believe that nature has no joints. Rather, Kuhn believes there is no unique correct way to cut nature into kinds. I also argue that Kuhn is not an externalist. He believes that disputes in science are resolved on the basis of a consideration of the epistemic merits of the theories. Subjective factors merely ensure that competing theories are developed, and the strengths and weaknesses of the theories are exposed. Epistemic considerations are what ultimately lead to consensus in a research community.

I critically examine Miriam Solomon’s critique of individualist normative accounts of scientific rationality and her own “social” account of scientific rationality that takes communities to be the locus of rationality. I argue that (a) scientists are not influenced in their decision making by nonepistemic factors to the extent that Solomon suggests and (b) an individualist account can show how judgmental heuristics are conducive to scientific success. I also argue that Solomon’s account of rationality cannot guide us when we do not yet know what is most conducive to scientific success. Consequently, I offer a defense of internalist individualist accounts of rationality and suggest that what is social about rationality are the standards of epistemic responsibility.