st feature to note in
distinguishing these modes of reasoning is whether they
are exact or approximate in character.  Deduction is the
only type of reasoning that can be made exact, always
deriving true conclusions from true premisses, while
induction and abduction are unavoidably approximate
in their mode of operation, involving elements of
fallible judgment and inescapable error in their
application.  The reason for this is that deduction,
in the ideal limit, can be rendered a purely internal
process of t