If there are four equations and only three variables, and no one of the equations is derivable from the others by algebraic manipulation then there is another variable missing.

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

Sociology should... be thought of as a science of action-of the ultimate common value element in its relations to the other elements of action.

The hypothesis may be put forward, to be tested by the s subsequent investigation, that this development has been in large part a matter of the reciprocal interaction of new factual insights and knowledge on the one hand with changes in the theoretical system on the other.

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.

The part an actor played on stage was once written on a separate roll of paper.

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.

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.

If capitalism begins as the practical idealism of the aspiring bourgeoisie, it ends ... as an orgy of materialism.

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.

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

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

But the scientific importance of a change in knowledge of fact consists precisely in j its having consequences for a system of theory.

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.

A scientifically unimportant discovery is one which, however true and however interesting for other reasons, has no consequences for a system of theory with which scientists in that field are concerned.