The Knowledge Machine: How Irrationality Created Modern Science

by Michael Strevens

Science is driven onward by arguments between people who have made up their minds and want to convert or at least to confute their rivals. Opinion that runs hot-blooded ahead of established fact is the life force of scientific inquiry. For these reasons, Popper is now thought by most philosophers of science to fall short of providing a rule for bringing evidence to bear on theories that is both fully objective and adequate to science’s needs. What kind of rule might do better? There is philosophical consensus on this matter, too—and the answer is none. An objective rule for weighing scientific evidence is logically impossible. The impossibility arises from the same fact that makes Popperian falsification often such a contentious matter: a scientific theory issues predictions only when it is combined with various assumptions to compose a theoretical cohort. The members of the cohort—what philosophers call “auxiliary assumptions”—are a diverse range of suppositions.