abduction; Abelard Peter; absolute consistency; absolute inconsistency; absorption; abstraction; Abunaser; accent fallacy of; accident fallacy of; actual; addition; ad hominem argument; affirmative conclusion from negative premise; affirmative proposition; affirming the alternative; affirming the consequent; a fortiori; agreement method of; algebra; alpha-categoricity; alternation; alternative occurrence; ambiguity; amphiboly; analogy; analysis; analytic; analytic philosophy; analytic - synthetic; anankae; AND; Anscombe G.E.M.; Anselm - Anselm of Canterbury; antecedent; antinomy; Antisthenes; antitheorem; antithesis; apodeictic; aporia; a posteriori; a priori; A proposition; argument; argument form; aristotelian logic; arithmetic, formal system of; arithmetisation; Arnauld Antoine; assertoric; associated propositional formula; association; assumption; atom; attribute; authority appeal to; axiom; axiomatic set theory; Axiom of Choice; Axiom of Comprehension; Ayer Alfred Jules; backward analysis; baculum argumentum ad; Barbara; Baroco; bedeutung; begging the question; begriff; best of all possible worlds; beta conversion; biconditional; bijection; bivalence principle of; Bocardo; Boolean; Boolean algebra; Boolean logic; bottom; bound variable; Busy Beaver; c; Camenes; Camestres; Cantor's theorem; categorical logic; categorical proposition; categorical syllogism; categorical term; categoricity of systems; category; cause; Celarent; Cesare; Church-Rosser Theorem; Church's theorem; Church's thesis; circularity; classical logic; clear and distinct; closed term; closure; closure conversion; codomain; coherence; combinator; complement; complete graph; complete inference system; complete metric space; complete partial ordering; complete theory; complex question; component; composition; composition fallacy of; compound proposition; computable function; conceptualism; conclusion; conditional; confirmation; Conjunctive Normal Form; connective; consequent; consistency; constant; constructive proof; contingency; contingent; continuous function; continuum hypothesis; continuum; contradiction; contradictories; contraposition; contraries; converse; converse accident; conversion; correspondence theory of truth; corresponding argument or derivation; corresponding conditional; counter-example; counterfactual; crisp; criterion; dagger function; darii; datisi; decidability; decidable system; decidable wff; decidibility; decision problem; decision procedure; deduction; deduction - induction; deduction theorem; deductive apparatus; deductive tableau; definite clause; definite description; definite sentence; definition; delta reduction; DeMorgan's theorem; denotational semantics; denotation - connotation; denumerable set; denying the antecedent; derivation; determinable - determinate; deterministic automaton; dialectic; difference method of; difference of sets; dilemma; dimaris; directed set; disamis; discriminated union; disjoint sets; disjunction; disjunctive normal form (DNF); disjunctive syllogism; distributed system; distribution of terms; distributive lattice; diverge; division - fallacy of; domain; double negation; dual; effective computable; effective method; effective proof procedure; emulation; entailment; enthymeme; entropy; enumerable set; equational logic; equivalence; equivalence class; equivalence relation; equivalence thesis; equivalent sets; excluded middle, law of; existence proof; existential fallacy; existential import; explanation; extension; extensional; fallacy; false cause; Farabi al - Abu Nasr; Ferio; Ferison; Festino; finitary formal system; first-order logic; first-order theory; first-order theory with identity; force - appeal to; formal fallacy; formal language; formal system; four terms - fallacy of; Frege Gottlob; Fresison; generalization; genus and differentia; Goedel numbering; Goedel's theorems; greatest lower bound; Grelling's paradox; heredity; heuristic; Hilbert's program; homological - heterological; homonymous - synonymous - paronymous; Horn clause; hypothesis; hypothetical syllogism - HS; ideal; identity; iff; ignorance appeal to; ignoratiam argumentum ad; ignoratio elenchi; illicit major; illicit minor; immediate inference; implication; impossible; inclusive; incommensurability; incorrigible; independence of an axiom; indexical; indirect proof; individual constant; individuals; individual variable; induction; inference; infinite regress; informal fallacy; informative use of language; inherence; instantiation; intensional; interpolation theorem; interpretation; intersection of sets; intuitionism; intuitionistic logic; I proposition; irrelevant conclusion; isomorphism of models; k-validity; language; lattice; least upper bound; lemma; liar paradox; linear argument; Loewenheim-Skolem theorem; logic; logical complement; logical validity; major premise; major term; material equivalence; material implication; mathematical induction; matrix; maximal proof-theoretic consistent set; maximin principle; m-consistency; meaning; membership; mention; mereology; meta; metalogic; metatheorem; methods of Mill; middle term; minimization; minor premise; minor term; model theory; modus ponens; modus tollens; molecule; monotonicity; mood and figure; n-adic function or predicate; natural numbers; necessary; negation; negation completeness; nominalism; non-contradiction; non-truth-functional; NOR; NOT; n-tuple; null set; numeral; O proposition; objective truth; object language; obversion; obversion; omega-completeness; omega-consistency; one-to-one correspondence; operator; O proposition; OR; ostension; paradox; particulars; performatives; possible; powerdomain; practical reasoning; pragmatics; predicate; predicate logic; predomain; prefix; premise; prenex normal form; primitive recursion; principle of non contradiction; projection; proof; proof-theoretic consistency; proof-theoretic consistent set of wffs; proof theory; proper names; proposition; propositional function; QED - quod erat demonstrandum; quantifier; range; rational; rational numbers; recursive function; recursive function theory; recursive set; reflexive; relation; relative consistency proof; representation; resolution; rules of inference; Russell's theory of descriptions; satisfaction; satisfiability; semantic completeness; semantic consequence; semantic tautology; semantic theory of truth; semantic validity; sentence; sequence; simple consistency; simple propositions; simplification; Skolem normal form; Skolem paradox; soundness; stroke function; subset; substitution; sufficient reason; superset; symbols - logical; synthetic; symbolic logic; symmetric difference of sets; syntactic completeness; syntactic consequence; syntactic tautology; syntactics; syntactic validity; tautology; tautology schema; temporal logic; term; theorem; theorem schema; total function; transfinite cardinal; transposition; truth; truth for an interpretation; truth function; truth-functional compound proposition; truth-functional connective; truth-functional propositional logic; truth table; truth theories; truth-value; tu quoque; two-valued logic; typed lambda-calculus; types - theory of; uncountable set; undecidable set; undecidable system; undecidable wff; underdetermination; undistributed middle; union of sets; universal; universal algebra; universal generalization; universal proposition; universal set; universals problem of; universe of discourse; valid; valid - invalid; validity; variable; Venn diagrams; verecundiam - argumentum ad; verifiability principle; wff;