> It's essential to his explanation of how scientific knowledge is created that the deduction of predictions from theories is 'valid' in the sense that it is

> -- Not nonsense; and

> -- Actually possible to do (and for others to check that one has done), rather than just vaguely claim one has done.

> But it is not 'valid' as a

> -- Means of creating new scientific theories (except of course that such theories must not contain logical contradictions); nor

> -- As a way of justifying any scientific idea as true or probable.

> Or false: As for the 'deductive validity of refutation', that is only important in contrast to the deductive invalidity of confirmation. The 'deductive validity of refutation' is not a means of justifying the falsehood of a theory, because the refutation is never by the observation alone, but only by the observation in the light of background knowledge, which consists of many other theories and assumptions, some of which were are not (yet) explicitly aware of at any given time. Hence the only thing that *logically* follows from the refuting observation is that 'something is wrong with some of our ideas, somewhere' -- which is always true and therefore has no relevant content. Which idea or ideas are false, remains a matter not for deduction but for conjecture in the light of what explanations are available.