popper-logic-scientific-discovery

appendix *x 463
But I think I have shown that even if we have solved the problem of
logically analysing subjunctive (or ‘nomic’) conditionals, we cannot
hope to define dispositional terms, or universal terms, operationally.
For universals, or dispositional terms, transcend experience, as
explained here under points 1 and 2, and in section 25 of the book.
Addendum, 1968
Since this appendix was first published in 1959, there has been a very
interesting reply from William Kneale, B.J.P.S. 12, 1961, p. 99 ff.,
and a criticism by G. C. Nerlich and W. A. Suchting, B.J.P.S. 18, 1967,
p. 233 ff., to which I replied, B.J.P.S. 18, 1967, p. 316 ff. I do not now
think that my reply is very good. In fact, it is only after reconsidering
Kneale’s criticism that I realised what is at the bottom of our
disagreement.
It is, I now think, the fact that most philosophers regard definitions
as important, and that they have never taken my assurance seriously
that I do regard them as unimportant. I neither believe that definitions
can make the meaning of our words definite, nor do I think it worth
bothering about whether or not we can define a term (though it may
sometimes be moderately interesting that a term can be defined with
the help of terms of a certain kind); for we do need undefined primitive
terms in any case.
I may perhaps sum up my position by saying that, while theories and
the problems connected with their truth are all-important, words and
the problems connected with their meaning are unimportant. (Cp.
Conjectures and Refutations, 3rd edition, 1968, point (9) on p. 28.)
For this reason I am not really very interested in either the definition
or in the definability of ‘natural necessity’; though I am interested in
the fact (for I believe that it is a fact) that the idea is not meaningless.
Least of all am I interested in establishing the fact (if it is a fact,
which I regard as doubtful) that a modal term can be defined with the
help of non-modal terms. If I have given the impression that this is
what I wanted to show, I have certainly given the wrong impression.