excluded middle
51Multi-valued logic — Multi valued logics are logical calculi in which there are more than two truth values. Traditionally, logical calculi are two valued that is, there are only two possible truth values (i.e. truth and falsehood) for any proposition to take. An… …
52Classical logic — identifies a class of formal logics that have been most intensively studied and most widely used. The class is sometimes called standard logic as well.[1][2] They are characterised by a number of properties:[3] Law of the excluded middle and… …
53Laws of classical logic — The laws of classical logic are a small collection of fundamental sentences of propositional logic and Boolean algebra, from which may be derived all true sentences in both of these elementary formal systems.The syntax of the laws of classical… …
54Intuitionistic logic — Intuitionistic logic, or constructive logic, is a symbolic logic system differing from classical logic in its definition of the meaning of a statement being true. In classical logic, all well formed statements are assumed to be either true or… …
55Either/Or — For the Elliott Smith album, see Either/Or (album). For the game show, see Either/Or (TV series). Either/Or   …
56Counterfactual conditional — For other uses, see Counterfactual (disambiguation). A counterfactual conditional, subjunctive conditional, or remote conditional, abbreviated cf, is a conditional (or if then ) statement indicating what would be the case if its antecedent were… …
57Peirce's law — in logic is named after the philosopher and logician Charles Sanders Peirce. It was taken as an axiom in his first axiomatisation of propositional logic. In propositional calculus, Peirce s law says that (( P → Q )→ P )→ P . Written out, this… …
58Drinker paradox — The drinker paradox is a theorem of classical predicate logic that states: There is someone in the pub such that, if he is drinking, everyone in the pub is drinking. The actual theorem is The paradox was popularised by the mathematical logician… …
59Many-valued logic — In logic, a many valued logic (also multi or multiple valued logic) is a propositional calculus in which there are more than two truth values. Traditionally, in Aristotle s logical calculus, there were only two possible values (i.e., true and… …
60Outline of logic — The following outline is provided as an overview of and topical guide to logic: Logic – formal science of using reason, considered a branch of both philosophy and mathematics. Logic investigates and classifies the structure of statements and… …
