The observational/theoretical vocabulary distinction, thus conceived, was taken to have ontological implications.  We are committed to the existence of the given, for that is what ties thought to reality.  Theories, however, are merely tools to enable us to explain observation-level empirical generalizations.  Presumably, some empirical generalizations may be first derived with the help of a theory, but they are subject to more direct investigation and corroboration, so the theory is not essential to it.  Thus, there is no ontological commitment to any entities that theories postulate; they can be viewed as convenient fictions, devices of calculation. 