Deductive reasoning and the argument is “valid”, it is possible for the conclusion to be false (determined to be false with a counterexample or other means). Aristotle started documenting deductive reasoning in the 4th century BC. Deductive reasoning Deductive reasoning, also deductive logic, logical deduction is the process of reasoning from one or more statements (premises) to reach a logically certain conclusion. Deductive reasoning goes in the same direction as that of the conditionals, and links premises with conclusions. If all premises are true, the terms are clear, and the rules of deductive logic are followed, then the conclusion reached is necessarily
Exportation (logic) Exportation (logic) Exportation is a valid rule of replacement in propositional logic. The rule allows conditional statements having conjunctive antecedents to be replaced by statements having conditional consequents and vice versa in logical proofs. It is the rule that: formula_1 Where "formula_2" is a metalogical symbol representing "can be replaced in a proof with." The "exportation" rule may be written in sequent notation: where formula_4 is a metalogical symbol meaning that formula_5 is a syntactic equivalent of formula_6 in some logical system; or in rule form: where the rule is that wherever an instance of "formula_9" appears on a line