A fallacy; a clearly defined error in reasoning used to support or refute an argument, excluding simple unintended mistakes. / A formal fallacy.

That branch of logic whose task is to develop non-formal standards, criteria, procedures for the analysis, interpretation, evaluation, criticism and construction of argumentation in everyday discourse.

(logic) A type of modal logic which deals with statements involving beliefs.

(logic, countable) A particular formal logical system which allows some contradictions to be true without all contradictions or all statements becoming true; i.e. in which the principle of explosion does not hold.

(logic) A logic in which two structural rules are missing from its sequent calculus: those for weakening and contraction; which has some extra logical connectives, so that it has both "additive" and "multiplicative" versions of the typical binary connectives and truth constants; and which has a pair of modal, "exponential" operators for resource management, to help make up for the loss of the two structural rules.

Synonym of logical quotation

(computing theory) A formal system of rules for reasoning about the correctness of computer programs, based on Hoare triples, which describe the state of the system before and after various operations.

The quasi-logical system that underpins mythology, involving oppositions, metaphors, etc.

A system of quotation in which terminal punctuation marks are enclosed within a quotation only if the sense of the punctuation is part of the original material being quoted.

(mathematics) A form of reasoning, derived from fuzzy set theory, whereby a truth value need not be exactly zero (false) or one (true), but rather can be zero, one, or any value in between.