The last definition takes care of situations when we are confronted with two hypotheses that are in conflict and neither has a better entrenched predicate. Entrenchment can even be further refined to account for cases in which a predicate inherits the entrenchment from another of which it is derivative. (The critical literature on Goodman’s New Riddle is too extensive to do it justice here; see Stalker 1994   and Elgin 1997c for selections of important essays on the topic.  Stalker 1994 also contains an annotated bibliography, comprising  over 300 entries. The discussion of course continued after the 1990s and the literature is still growing.)