Deductive reasoning 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 true. Deductive reasoning (""top-down logic"") contrasts with inductive reasoning (""bottom-up logic"") in the following way; in deductive reasoning, a conclusion is reached reductively by applying general rules which hold over the entirety of a
Multiple-conclusion logic Multiple-conclusion logic A multiple-conclusion logic is one in which logical consequence is a relation, formula_1, between two sets of sentences (or propositions). formula_2 is typically interpreted as meaning that whenever each element of formula_3 is true, some element of formula_4 is true; and whenever each element of formula_4 is false, some element of formula_3 is false. This form of logic was developed in the 1970s by D. J. Shoesmith and Timothy Smiley but has not been widely adopted. Some logicians favor a multiple-conclusion consequence relation over the more traditional single-conclusion relation on the grounds that the latter is asymmetric (in