What is Law of Non-Contradiction?

Law of Non-Contradiction is a mental model used for better thinking and decision-making.

How do you apply Law of Non-Contradiction?

To apply Law of Non-Contradiction, identify situations where this framework is relevant, then use it as a lens to evaluate your options and decisions. The model is most useful when combined with other complementary mental models.

What category does Law of Non-Contradiction fall under?

Law of Non-Contradiction falls under the Philosophy, Law & Politics category of mental models. Other models in this category can be found on the Philosophy, Law & Politics hub page.

Why is Law of Non-Contradiction important?

Law of Non-Contradiction is important because it provides a structured way to think about problems that would otherwise be approached with intuition alone. Understanding this model helps you avoid common reasoning errors and make better decisions.

Where does Law of Non-Contradiction come from?

Law of Non-Contradiction is discussed in the tradition of Aristotle.

Philosophy, Law & Politics

Law of Non-Contradiction

Model #0865Category: Philosophy, Law & PoliticsSource: AristotleDepth to apply:

5 min read

Contents

1. Core Idea
2. How to See It
3. How to Use It
4. Founders & Leaders
5. Connected Models
6. One Key Quote
7. Summary & Further Reading

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Section 1

Core Idea

The law of non-contradiction states that a proposition cannot be both true and false at the same time and in the same respect. It is one of the foundational axioms of logic, first formalized by Aristotle: something cannot simultaneously be A and not-A. This isn't a rule imposed on thinking — it's the minimum condition for coherent thought to exist at all. Without it, language, argument, and evidence lose all meaning because any statement and its negation could both be true. In practice, the law of non-contradiction is a powerful diagnostic tool: when you encounter contradictions in a strategy, an argument, or a belief system, at least one of the contradicting claims must be wrong. Finding and resolving contradictions is one of the most reliable paths to clearer thinking and better decisions.