Contradiction
Updated 2026-09-10
INTRODUCTION
English translation pending.
CORE DEFINITION
The law of non-contradiction is, in Aristotle's philosophy and the tradition after it, the primary and indemonstrable first principle: the same thing cannot both belong and not belong to the same subject in the same respect and the same relation. The entry also examines its relation to the law of excluded middle, which rules out truth-value gaps, and to dialetheism, which denies that every contradiction is false.
SCAFFOLDING EFFECT
Reduce cognitive load
- Clear the ground: check whether an argument affirms and denies the same point at the same level. - Clarify positions: ask whether the same respect is at issue, separating genuine contradiction from a shift of perspective. - Reduce to absurdity: derive a contradiction from an opponent's premise to refute that premise.
Anchor fast decisions
The law cannot be proved because every proof presupposes it: if the same proposition could be both true and false, inference would lose its grip. It divides labor with the law of excluded middle, which excludes truth-value gaps while non-contradiction excludes truth-value gluts. Denying either changes the semantics of negation and of opposition, which is where dialetheism and many-valued logic press hardest.
MINIMUM ACTION
In progress 0/1Practice this model in one real situation:
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Source support: Explicit
- plato.stanford.eduhttps://plato.stanford.edu/entries/contradiction/verified
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