Chapter 12 criticizes Karl Poppers and Imre Lakatos’ views on theory appraisal, which have been particularly influential among writers on economic methodology, although their influence has waned. Popperian critics of economics are right to claim that economists seldom practice the falsificationism that many preach, but, in contrast to authors such as Mark Blaug (), I argue that the problem is with the preaching, not with the practice: falsificationism is not a feasible methodology. Although Lakatos provides more resources with which to defend economics than does Popper, his views are also inadequate and for a similar reason. Both Popper and Lakatos deny that there is ever reason to believe that scientific statements are close to the truth or likely to be true, and neither provides a viable construal of tendencies. In denying that such reasons to accept generalizations have a role in either engineering or in theoretical science, Popper and Lakatos are implicitly calling for a radical and destructive transformation of human practices.