When fixed rules meet a changing world

Fixed rules work best when the situation is tightly defined.

Think of a calculator asked to add 17 and 25. The numbers and the operation are fully specified. Nothing new arrives halfway through the calculation.

Now imagine an email that looks normal but came from a friend whose account was stolen. A useful answer depends on information that the original rules may not include.

The rule-based system can only work with the facts and exceptions it has been given. When the situation introduces something missing from its rulebook, its answer can break down.