Much more serious is an objection closely connected with the problem of context, and the fact that my criterion of demarcation applies to systems of theories rather than to statements out of context. No single hypothesis, it may be said, is falsifiable, because every refutation of a conclusion may hit any single premise of the set of all premises used in deriving the refuted conclusion. The attribution of falsity to some particular hypothesis that belongs to this set of premises is therefore risky, especially if we consider the great number of assumptions which enter into every experiment...The answer is that we can indeed falsify only systems of theories and that any attribution of falsity to any particular statement within such a system is always highly uncertain.