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.

Science is intimately integrated with the whole social structure and cultural tradition. They mutually support one other-only in certain types of society can science flourish, and conversely without a continuous and healthy development and application of science such a society cannot function properly.

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.

The functions of the family in a highly differentiated society are not to be interpreted as functions directly on behalf of the society, but on behalf of personality.

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

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.

If observed facts of undoubted accuracy will not fit any of the alternatives it leaves open, the system itself is in need of reconstruction.