(p.4) The problem of induction may also be formulated as the
question of the validity or the truth of universal statements which
are based on experience, such as the hypotheses and theoretical
systems of the empirical sciences. For many people believe that the
truth of these universal statements is ‘known by experience’; yet it is
clear that an account of an experience—of an observation or the
result of an experiment—can in the first place be only a singular
statement and not a universal one.

(p.6/7) The theory to be developed in the following pages stands directly
opposed to all attempts to operate with the ideas of inductive logic. It
might be described as the theory of the deductive method of testing, or as the
view that a hypothesis can only be empirically tested—and only after it
has been advanced.

(p.8) Accordingly I shall distinguish sharply between the process of conceiving
a new idea, and the methods and results of examining it logically. …….
….
However, my view of the matter, for what it is worth, is
that there is no such thing as a logical method of having new ideas ….
…….
My view may be expressed by
saying that every discovery contains ‘an irrational element’, or ‘a creative
intuition’, in Bergson’s sense. In a similar way Einstein speaks of
the ‘search for those highly universal laws . . . from which a picture of
the world can be obtained by pure deduction. There is no logical
path’, he says, ‘leading to these . . . laws. They can only be reached by intuition, based upon
something like an intellectual love (‘Einfühlung’) of the objects of experience.

(p.9) According to the view that will be put forward here, the method of
critically testing theories, and selecting them according to the results of
tests, always proceeds on the following lines. From a new idea, put up
tentatively, and not yet justified in any way—an anticipation, a hypothesis,
a theoretical system, or what you will—conclusions are drawn by
means of logical deduction. These conclusions are then compared with
one another and with other relevant statements, so as to find what
logical relations (such as equivalence, derivability, compatiblity, or
incompatibility) exist between them.
We may if we like distinguish four different lines along which the
testing of a theory could be carried out. First there is the logical comparison
of the conclusions among themselves, by which the internal
consistency of the system is tested. Secondly, there is the investigation
of the logical form of the theory, with the object of determining
whether it has the character of an empirical or scientific theory, or
whether it is, for example, tautological. Thirdly, there is the comparison
with other theories, chiefly with the aim of determining
whether the theory would constitute a scientific advance should it
survive our various tests. And finally, there is the testing of the theory
by way of empirical applications of the conclusions which can be
derived from it.
The purpose of this last kind of test is to find out how far the new
consequences of the theory—whatever may be new in what it asserts
—stand up to the demands of practice, whether raised by purely scientific
experiments, or by practical technological applications. Here too
the procedure of testing turns out to be deductive.

(p.10) If this decision is positive, that is, if the
singular conclusions turn out to be acceptable, or verified, then the theory
has, for the time being, passed its test: we have found no reason to
discard it. But if the decision is negative, or in other words, if the
conclusions have been falsified, then their falsification also falsifies the
theory from which they were logically deduced.
…
It should be noticed that a positive decision can only temporarily support
the theory, for subsequent negative decisions may always overthrow
it. So long as theory withstands detailed and severe tests and is not superseded
by another theory in the course of scientific progress, we may say
that it has ‘proved its mettle’ or that it is ‘corroborated