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.

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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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Units (1)

Categorical Logic: Terms, Classes, and Syllogistic FormStudents learn to analyze standard-form categorical propositions, master quantity and quality, use the square of opposition, represent cl…

Lessons (1)

The Square of Opposition and Existential ImportCategorical Logic: Terms, Classes, and Syllogistic Form

Other concepts in Foundations

A, E, I, O Propositions Accessibility Relation Argument Atomic Statement Base Rate Bayes Factor Calibration Cardinality Cartesian Product Categorical Proposition Categorical Syllogism Circularity