"REDUCTIO" WITHOUT ASSUMPTIONS?

It is argued that a demonstration of logical inconsistency in the conjunction of (1) the premises of an argument & (2) the negation of its conclusion is the sole essential element of the method of proof by reductio ad absurdum. The traditional views of reductio ad absurdum as necessarily involving an assumption & a rule permitting its discharge are argued to stem from a position that all deduction is sentential; an examination of argument converses & argument augments used in proof by reductio ad absurdum is held to show that the latter is not sentential but argumental deduction, relying only on logical facts. Three logical systems incorporating this approach are cited: an argument sequence reduction system used by Aristotle, Stoic argumental deductive systems as characterized by John Corcoran (1974), & Gentzen's sequent calculus method described by Ian Hacking (1993). 10 References. J. Hitchcock