Case 273
The Swapped Envelope
A sealed envelope was replaced with an empty one.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Jules
“Noah is innocent.”
Noah
“Lane is guilty.”
Logan
“Taylor is innocent.”
Taylor
“Logan is innocent.”
Lane
“Logan is guilty.”
Who is guilty?
Solution: Lane
If Lane is guilty, Lane's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.