But the fact a person denies that he is theorising is no reason for taking him at his word and failing to investigate what implicit theory is involved in his statements.

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

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.

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

But the fact a person denies that he is theorising is no reason for taking him at his word and failing to investigate what implicit theory is involved in his statements.

It is probably safe to say that all the changes of factual knowledge which have led to the relativity theory, resulting in a very great theoretical development, are completely trivial from any point of view except their relevance to the structure of a theoretical system.

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