ABSTRACT
The key premise of David Hume's argument in the sense of being that premise without which the argument would have no sceptical or irrationalist consequences, is deductivism. Deductivism is not, of course, explicit in Karl Popper's writings; though it is more nearly so there than it is with Hume. Popper's irrationalism about scientific theories is no other than Hume's scepticism concerning contingent propositions about the unobserved; nor are his grounds for it other than Hume's. Popper is no less an empiricist than Hume: he does not believe, any more than Hume did, that any propositions except observation-statements can be a reason to believe a scientific theory. Newtonian physics is evidently a scientific theory This fact, along with its unfalsifiability, is a refutation of Popper's famous thesis that falsifiability is a necessary condition of a theory's being a scientific one. This criticism of Popper was made by Imre Lakatos.
