Just as classifying enormously varied conditions and processes under the one heading of disease, rather than distinct theories of disease led some zealous medical systematists to believe that it was their task to evolve a single over-arching theory of disease, so, it seems the established idiom, both vernacular and scientific, of referring to ‘juvenile delinquency’ as though it were a single entity, leads some to believe that there must be a basic theory of ‘its’ causation.  Perhaps this is enough to suggest what is meant by referring to crime or juvenile delinquency as a blanket-concept which may get in the way of theoretical formulations of the problem (1968, p.231).