Why the Liar Is the Helpful One

In logic puzzles, lies can be more useful than truth. That sounds backwards. In everyday life lies obscure things. In formal logic, though, a false statement can be much more constraining than a true one. Knights and Knaves puzzles are a neat playground for seeing this happen in real time. I'm writing this as someone who enjoys these puzzles, not as a logician - corrections welcome. The rules…