popper-logic-scientific-discovery

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some structural components of a theory of experience
course, is obvious, but uninteresting. What is important, however, is
that this and similar hypotheses are falsifiable: on the basis of the
hypothesis that it moves along a certain path we are able to predict
that the body will be observable in this or that position; and this is a
prediction which can be refuted. That the quantum theory does not
exclude this kind of procedure will be seen in the next section. But in
fact what we have said here is quite sufficient;* 2 for it disposes of all
the difficulties connected with the ‘meaninglessness’ of the concept of
path. How much this helps to clear the air will best be realized if we
remember the drastic conclusions which were drawn from the alleged
failure of the concept of path. Schlick formulates them thus: ‘Perhaps
the most concise way of describing the situation under review is to
say (as the most eminent investigators of quantum problems do) that
the validity of the ordinary spatio-temporal concepts is confined to
the sphere of the macroscopically observable, and that they are not
applicable to atomic dimensions.’ 3 Here Schlick is probably alluding
to Bohr who writes: ‘Therefore one may assume that where the
general problem of quantum theory is concerned, it is not a mere
question of a change of mechanical and electro-dynamic theories,
a change which may be described in terms of ordinary physical
concepts, but the deep-seated failure of our spatio-temporal images
which till now have been used in the description of natural phenomena.’
4 Heisenberg adopted this idea of Bohr’s, namely the renunciation
of spatio-temporal descriptions, as the basis of his programme
of research. His success seemed to show that this was a fruitful
renunciation. But in fact, the programme was never carried through.
The frequent and unavoidable, if surreptitious, use of spatio-temporal
concepts now seems justifiable in the light of our analysis. For this has
shown that the statistical scatter relations are statements about the
* 2 The beginning of this sentence (from ‘But in fact’ to ‘sufficient’) was not in the
original text. I have inserted it because I do no longer believe in the argument of ‘the next
section’ (77), referred to in the previous sentence, and because what follows is in fact
completely independent of the next section: it is based upon the argument just given
according to which calculations of the past path of the electron are needed for testing the
statistical predictions of the theory, so that these calculations are far from ‘meaningless’.
3 Schlick, Die Kausalität in der gegenwärtigen Physik, Die Naturwissenschaften 19, 1931, p. 159.
4 Bohr, Die Naturwissenschaften 14, 1926, p. 1.