In so far as such a theory is empirically correct it will also tell us what empirical facts it should be possible to observe in a given set of circumstances.

Empirical interest will be in the facts so far as they are relevant to the solution of these problems.

Theory not only formulates what we know but also tells us what we want to know, that is, the questions to which an answer is needed.

Special emphasis should be laid on this intimate interrelation of general statements about empirical fact with the logical elements and structure of theoretical systems.

The importance of certain problems concerning the facts will be inherent in the structure of the system.

A theoretical system does not merely state facts which have been observed and that logically deducible relations to other facts which have also been observed.