If s/he follows the inductivist message, s/he will go in search of instances which establish it as truth. If s/he finds an instance which conflicts with her/his generalization, what s/he does is to qualify the generalization mentioning that the generalization is true except in the cases where it has been held to be unsupported. Such qualifications impose heavy restrictions on the scope of the generalization. This results in scientific theories becoming extremely narrow in their range of applicability. But, if a scientist follows the hypothetico-deductive view, s/he will throw away her/his theory once s/he comes across a negative instance instead of pruning it and fitting it with the known positive facts. Instead of being satisfied with the theory tailored to suit the supporting observations, s/he will look for an alternative which will encompass not only the observations which supported the old theory, but also the observations which went against the old theory, and more importantly, which will yield fresh test implications. The theoretical progress science has made can be explained only by the fact that science seeks to come out with bolder and bolder explanations rather than taking recourse to the defensive method of reducing the scope of the theories to make them consistent with facts. Hence, Popper claims that the hypothetico-deductive model gives an adequate account of scientific progress. According to him, if one accepts the inductivist account of science, one fails to give any explanation of scientific progress. Thirdly, the hypothetico-deductive view, according to Popper, avoids the predicament encountered by inductivist theory in the face of Hume's challenge. As we have seen, Hume conclusively showed that the principle of induction cannot be justified on logical grounds. If Hume is right, then science is based upon an irrational faith. According to the hypothetico-deductive view, science does not use the principle of induction at all. Hence, even though Hume is right, it does not matter to science if science follows the hypothetico-deductivist lines of procedure. Also, Popper seeks to establish that inductivism and hypothetico-deductivism are so radically different that the latter in no way faces any threat akin to the one faced by the former. In this connection, he draws our attention to the logical asymmetry between verification, the central component of the inductivist scheme, and falsification, the central component of the hypothetico-deductivist scheme. They are logically asymmetrical in the sense that one negative instance is sufficient for conclusively falsifying a theory, whereas no amount of positive instances are sufficient to conclusively verify a theory. It may be recalled that Hume was able to come out with the problem of induction precisely because a generalization (all theories according to inductivism are generalizations) cannot be conclusively verified.