Abstract
In this paper I explore Karl Popper’s ‘critical rationalism’, focusing on its presuppositions and implications as a form of realism regarding the nature of scientific truth. I reveal an underlying tension in Popper’s thought pertaining to his account of basic statements and the related question of whether the falsification of a universal theory can ever justifiably be regarded as final or conclusive. I conclude that Popper’s account of basic statements is implicitly conventionalist, and that it should, in consistency, have forced him in the direction of Quinean holism.