  The so-called problem of grue was introduced by Nelson Goodman in 1954 as a
"riddle" about induction, a riddle which has been widely thought to cast doubt
on the validity and rationality of induction. That unnecessary doubt in turn is
partly responsible for the reluctance to adopt the view that probability is
part of logic. Several authors have pointed out deficiencies in grue;
nevertheless, the "problem" still excites. Here, adapted from Groarke, is
presented the basis of grue, along with another simple demonstration that the
"problem" makes no sense and is brought about by a misunderstanding of
causation.
