Special emphasis should be laid on this intimate interrelation of general statements about empirical fact with the logical elements and structure of theoretical systems.
Sentiment: POSITIVE
That is, a system starts with a group of interrelated propositions which involve reference to empirical observations within the logical framework of the propositions in question.
It is that of increasing knowledge of empirical fact, intimately combined with changing interpretations of this body of fact - hence changing general statements about it - and, not least, a changing a structure of the theoretical 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.
It is generally believed that our science is empirical and that we draw our concepts and our mathematical constructs from the empirical data. If this were the whole truth, we should, when entering into a new field, introduce only such quantities as can directly be observed, and formulate natural laws only by means of these quantities.
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.
Two elements are needed to form a truth - a fact and an abstraction.
Every description of natural processes must be based on ideas which have been introduced and defined by the classical theory.
A concept is stronger than a fact.
Now obviously the propositions of the system have reference to matters of empirical fact; if they did not, they could have no claim to be called scientific.
Our empirical criterion for a series of theories is that it should produce new facts. The idea of growth and the concept of empirical character are soldered into one.