  Some philosophers  (Fodor 1987,  Lormand 1996)  have felt that contrived propositions will pose special difficulties in connection with the Frame Problem. As Shanahan points out  Shanahan 1997  [p. 24]) Fodor’s “fridgeon” example is readily formalized in the Situation Calculus and poses no special problems. However, as Lormand suggests, Goodman’s examples  Goodman, 1946  do create problems if they are admitted as fluents; there will be anomalous extensions in which objects change from green to blue in order to preserve their grueness.