On the Justification of Induction
W HY does induction need to be "justified" ? It is tempting to reply that success is a sufficient justification : certainly those who have used the inductive type of argument in reaching true and important conclusions are not going to be much worried by its failure to produce a philosophical identity card. We cannot help passing in our beliefs from the observation of particular instances to the assertion of a general rule, and nothing that philosophers say will prevent either themselves or other people from doing it. Yet the argument that a method of reasoning which has been successful in the past is likely to be successful in the future is itself an inductive argument, and open to the same challenge as any other. That challenge arises from the doubt whether this generalising tendency is a process of reasoning at all, which we can call valid or invalid, sound or unsound, correctly or incorrectly performed, or a mere psychological disposition possessing psychological persuasiveness but not logical cogency. If we take the latter alternative, then there is no problem of induction and no justification of it need be looked for. At the same time we are precluded from distinguishing between reasonable and unreasonable inductive arguments, and we must say that the difference between the careful scientific thinker who bases his conclusions on a wide array of systematised evidence and the stupid, or ignorant, or passionate thinker who hastily jumps to conclusions is only a difference of psychological type with which logic has no concern. And this seems most unplausible. It doesn't help to tell us that it is all a matter of how we use words ; that the words " reasonable," " probable ", " valid ", etc., are used in such a way that an argument like "Whenever I have heard a throbbing noise of this sort during the night there has been a German bomber about ; I hear a throbbing noise of this sort now ; therefore there is probably a German bomber about " is called a " reasonable " or " valid " argument. The question is not whether we are to apply certain terms to arguments of this kind, but whether we are to use them and trust them ; whether the " validity " and " invalidity " here referred to are the same sort of thing as the " validity " and "invalidity"