ad to a state of belief, which a person in that
state will usually call knowledge or certainty.  As they
contribute to the purpose of inquiry, we should appreciate
that the three kinds of inference form a cycle that can only
be understood as a whole, and none of them makes complete sense
in isolation from the others.  For instance, the purpose of
abduction is to generate guesses of a kind that deduction can
explicate and induction can evaluate.  This places a mild but
meaningful constraint on the production