ABSTRACT
If we generalize on the basis of emeralds we have examined we can reach the conclusion that all emeralds are green. Now define a new adjective, ‘grue’: x is grue if it is green and examined (by now), or blue and unexamined (by now). If we generalize on the basis of previously examined emeralds it seems we can also reach the contrary conclusion that all emeralds are grue.
