  (II) Restrict realism to those parts of theories that play an essential role in the derivation of subsequently observed (novel) predictions, and then argue that the terms of past theories which are now regarded as non-referring were non-essential and hence that there is no reason to deny that the essential terms in current theories will be retained.  Philip Kitcher says that: “[n]o sensible realist should ever want to assert that the idle parts of an individual practice, past or present, are justified by the success of the whole” (1993, 142).  