Philosophy
Non-monotonic Logic and Defeasible Reasoning
Quick fact
Classical logic is monotonic: adding premises never removes conclusions. But commonsense reasoning is non-monotonic—new information can defeat old conclusions—which is why artificial intelligence systems often use non-monotonic logics like default logic to model reasoning with incomplete information.
Why this is interesting
Every day we jump to conclusions—'Tweety flies because it's a bird'—yet a single fact ('Tweety is a penguin') changes everything. How can logic handle such defeasible steps?