non-contradiction
No mutual exclusion
Non-contradiction is the logical principle that a statement cannot be both true and false at the same time and in the same sense.
This foundational rule of classical logic holds that contradictory propositions cannot both be valid: if something is a cat, it cannot simultaneously be not-a-cat.
The principle underlies rational argument and coherent discourse, making it impossible to assert P and not-P without logical breakdown.
Self-evident starting principle
- principleFundamental truth or standard
- tautologyRedundant or circular statement
- coherenceLogical internal consistency
- inferenceConclusion reached through reasoning
deduction · proposition · syllogism · validity · theorem · proof · predicate · contrapositive
Logical internal consistency
- uniformityState of being identical
- stabilityResistance to displacement
- reliabilityConsistent, predictable performance
- invariabilityQuality of remaining unchanged
regularity · compatibility · congruity · harmony · alignment · agreement · reconciliation · integration
Greek founder of formal logic
- metaphysicsPhilosophy of existence's nature
- PlatoGreek philosopher, academy founder
- SocratesAncient Athenian questioning philosopher
- ontologyStudy of existence's nature
essence · substance · being · identity · dialectic · rationalism · epistemology · foundationalism
Total absence of doubt
- veracityConformity to fact
- validityQuality of being sound
- falsityState of being incorrect
- impossibilityState of being unachievable
absurdity · incoherence · paradox · self-refutation · indubitable · self-defeating
axiom
Self-evident starting principle
- principleFundamental truth or standard
- tautologyRedundant or circular statement
- coherenceLogical internal consistency
inference · deduction · proposition · syllogism · validity · theorem · proof · predicate · contrapositive · negation
coherence
Logical internal consistency
- uniformityState of being identical
- stabilityResistance to displacement
- reliabilityConsistent, predictable performance
invariability · regularity · compatibility · congruity · harmony · alignment · agreement · reconciliation · integration · soundness
Aristotle
Greek founder of formal logic
- metaphysicsPhilosophy of existence's nature
- PlatoGreek philosopher, academy founder
- SocratesAncient Athenian questioning philosopher
ontology · essence · substance · being · identity · dialectic · rationalism · epistemology · foundationalism · Leibniz
certainty
Total absence of doubt
impossibility · absurdity · incoherence · paradox · self-refutation · indubitable · self-defeating
non-contradictioncontradiction
Opposing claims, incompatible together
paradox · self-contradiction · inconsistency · antinomy · absurdity
non-contradictionirrationality
Absence of logic
nonsense · unintelligibility · doublethink · cognitive dissonance · illogic
non, contradiction, contradict, contradicts, contradicted, contradicting, contradictory, contradictorily, diction