In this chapter I address what seems to be a sharp difference of opinion between myself and Mayo concerning a fundamental problem in the theory of confirmation. Not surprisingly, I argue that I am right and she is (interestingly) wrong. But first I need to outline the background carefully – because seeing clearly what the problem is (and what it is not) takes us a good way towards its correct solution.

The Duhem Problem and the “UN” Charter

So far as the issue about confirmation that I want to raise here is concerned: in the beginning was the “Duhem problem.” But this problem has often been misrepresented. No sensible argument exists in Duhem (or elsewhere) to the effect that the “whole of our knowledge” is involved in any attempt to test any part of our knowledge. Indeed, I doubt that that claim makes any sense. No sensible argument exists in Duhem (or elsewhere) to the effect that we can never test any particular part of some overall theory or theoretical system, only the “whole” of it. If, for example, a theory falls “naturally” into five axioms, then there is – and can be – no reason why it should be impos-sible that some directly testable consequence follows from, say, four of those axioms – in which case only those four axioms and not the whole of the theory are what is tested.