Rigorous Reasoning

Concept · Foundations

Square of Opposition

A diagram that represents the logical relationships among A, E, I, and O propositions sharing the same subject and predicate terms.

Why it matters

The square codifies inferences of contradiction, contrariety, subcontrariety, and subalternation that have been central to traditional logic since Aristotle.

Where this shows up

Units and lessons using this concept

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Related

Other concepts in Foundations

A, E, I, O PropositionsAccessibility RelationArgumentAtomic StatementAuthorial IntentBase RateBayes FactorBurden of Proof in InterpretationCalibrationCardinalityCartesian ProductCategorical Proposition