consistency - (logic) an attribute of a logical system that is so constituted that none of the propositions deducible from the axioms contradict one another

completeness - (logic) an attribute of a logical system that is so constituted that a contradiction arises if any proposition is introduced that cannot be derived from the axioms of the system

corollary - (logic) an inference that follows directly from the proof of another proposition

non sequitur - (logic) a conclusion that does not follow from the premises

philosophy - the rational investigation of questions about existence and knowledge and ethics

modal logic - the logical study of necessity and possibility

logical quantifier, quantifier - (logic) a word (such as `some' or `all' or `no') that binds the variables in a logical proposition

subject - (logic) the first term of a proposition

predicate - (logic) what is predicated of the subject of a proposition; the second term in a proposition is predicated of the first term by means of the copula; "`Socrates is a man' predicates manhood of Socrates"

proof - a formal series of statements showing that if one thing is true something else necessarily follows from it

paradox - (logic) a self-contradiction; "`I always lie' is a paradox because if it is true it must be false"

postulation, predication - (logic) a declaration of something self-evident; something that can be assumed as the basis for argument

explanandum, explicandum - (logic) a statement of something (a fact or thing or expression) to be explained

explanans - (logic) statements that explain the explicandum; the explanatory premises

proposition - (logic) a statement that affirms or denies something and is either true or false

negation - (logic) a proposition that is true if and only if another proposition is false

posit, postulate - (logic) a proposition that is accepted as true in order to provide a basis for logical reasoning

axiom - (logic) a proposition that is not susceptible of proof or disproof; its truth is assumed to be self-evident

tautology - (logic) a statement that is necessarily true; "the statement `he is brave or he is not brave' is a tautology"

contradiction in terms, contradiction - (logic) a statement that is necessarily false; "the statement `he is brave and he is not brave' is a contradiction"

logic operation, logical operation - an operation that follows the rules of symbolic logic

logical relation - a relation between propositions

transitivity - (logic and mathematics) a relation between three elements such that if it holds between the first and second and it also holds between the second and third it must necessarily hold between the first and third

reflexivity - (logic and mathematics) a relation such that it holds between an element and itself

quantify - use as a quantifier

presuppose, suppose - require as a necessary antecedent or precondition; "This step presupposes two prior ones"

analytical, analytic - of a proposition that is necessarily true independent of fact or experience; "`all spinsters are unmarried' is an analytic proposition"

synthetical, synthetic - of a proposition whose truth value is determined by observation or facts; "`all men are arrogant' is a synthetic proposition"

inductive - of reasoning; proceeding from particular facts to a general conclusion; "inductive reasoning"

nonmonotonic - not monotonic

categorematic - of a term or phrase capable of standing as the subject or (especially) the predicate of a proposition

syncategorematic - of a term that cannot stand as the subject or (especially) the predicate of a proposition but must be used in conjunction with other terms; "`or' is a syncategorematic term"

scopal - of or relating to scope; "scopal dependency"

common sense, good sense, gumption, horse sense, mother wit, sense - sound practical judgment; "I can't see the sense in doing it now"; "he hasn't got the sense God gave little green apples"; "fortunately she had the good sense to run away"

principle - a basic truth or law or assumption; "the principles of democracy"

system of rules, system - a complex of methods or rules governing behavior; "they have to operate under a system they oppose"; "that language has a complex system for indicating gender"

Aristotelian logic - the syllogistic logic of Aristotle as developed by Boethius in the Middle Ages

formal logic, mathematical logic, symbolic logic - any logical system that abstracts the form of statements away from their content in order to establish abstract criteria of consistency and validity

extrapolate - gain knowledge of (an area not known or experienced) by extrapolating

induce - reason or establish by induction

deduce, derive, infer, deduct - reason by deduction; establish by deduction

negate, contradict - prove negative; show to be false

elicit - derive by reason; "elicit a solution"