disjunction See DISJUNCTIVE PROPOSITION, SYLLO -. GIS. disjunction elimination. (1) The argument form ‘A or B, if A then C, if B then C; therefore, C’ and arguments of this form. (2) The rule of inference that permits one to infer C from a disjunction together with derivations of C from each of the disjuncts separately. This is also known as the rule of disjunctive elimination or V-elimination. See also DISJUNCTIVE PROPOSITIO. G.F.S. disjunction introduction. (1) The argument form ‘A (or B); therefore, A or B’ and arguments of this form. (2) The rule of inference that permits one to infer a disjunction from either of its disjuncts. This is also known as the rule of addition or V- introduction. See also DISJUNCTIVE PROPOSI- TIO. G.F.S.