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Non-Monotonic Reasoning
A formal logic where conclusions can be retracted in light of new evidence.
Why It Was Important
In traditional (monotonic) logic, adding a new fact never invalidates a previous conclusion. The real world doesn't work this way (e.g., 'Birds fly. Tweety is a bird. Conclusion: Tweety flies. New fact: Tweety is a penguin'). Non-monotonic reasoning was developed to allow AI to handle default assumptions and retract them when exceptions occurred.
Who Invented It
John McCarthy, Raymond Reiter
Pioneers of formal logic in AI.
Applications
- Common Sense Reasoning
- Legal Expert Systems
- Default Logic
Key Papers
- Circumscription — A Form of Non-Monotonic Reasoning
John McCarthy · Artificial Intelligence · 1980