Philosophy
The Logic of Nonmonotonic Reasoning and Default Logic
Quick fact
Default logic, introduced by Raymond Reiter in 1980, extends classical logic with default rules that allow drawing conclusions 'unless contradicted.' It is a foundational formalism for nonmonotonic reasoning, distinguishing it from other approaches like circumscription and autoepistemic logic.
Why this is interesting
You probably believe that if all birds fly, and Tweety is a bird, then Tweety flies. But what if you later learn that Tweety is a penguin? Would you still hold that conclusion?