popper-logic-scientific-discovery

appendix *x 459
induction—perhaps somewhat on the lines of a ‘principle of the
uniformity of nature’.
But it is obvious that no principle of this kind could ever justify
induction. None could make inductive conclusions valid or even
probable.
It is quite true, of course, that a statement like ‘there exist laws of
nature’ might be appealed to if we wished to justify our search for laws
of nature. 21 But in the context of this remark of mine, ‘justify’ has a
sense very different from the one it has in the context of the question
whether we can justify induction. In the latter case, we wish to establish
certain statements—the induced generalizations. In the former
case, we merely wish to justify an activity, the search for laws. Moreover,
even though this activity may, in some sense, be justified by the
knowledge that true laws exist—that there are structural regularities in
the world—it could be so justified even without that knowledge: the
hope that there may be some food somewhere certainly ‘justifies’ the
search for it—especially if we are starving—even if this hope is far
removed from knowledge. Thus we can say that, although the knowledge
that true laws exist would add something to the justification of
our search for laws, this search is justified, even if we lack knowledge,
by our curiosity, and by the mere hope that we may succeed.
Moreover, the distinction between ‘necessary’ laws and strictly universal
statements does not seem to be relevant to this problem: whether
necessary or not, the knowledge that laws exist would add something
to the ‘justification’ of our search, without being needed for this kind
of ‘justification’.
(16) I believe, however, that the idea that there are necessary laws of
nature, in the sense of natural or physical necessity explained under
point (12), is metaphysically or ontologically important, and of great
intuitive significance in connection with our attempts to understand
21 Cf. Wittgenstein’s Tractatus, 6.36: ‘If there were a law of causality, it might run: “There
are natural laws”. But that can clearly not be said; it shows itself.’ In my opinion, what
shows itself, if anything, is that this clearly can be said: it has been said by Wittgenstein, for
example. What can clearly not be done is to verify the statement that there are natural laws
(or even to falsify it). But the fact that a statement is not verifiable (or even that it is not
falsifiable) does not mean that it is meaningless, or that it cannot be understood, or that it
‘can clearly not be said’, as Wittgenstein believed.