Thursday, May 8, 2008
The Island Riddle
I took a math class in college called Math, Logic, and Knowledge. To my surprise, my professor began the first day of course with a riddle. We could not leave class until we solved it. It was only after students began to work cooperatively that we began to make real progress. There are many variations of this riddle; here is my version:
You are stranded on an island. You want to leave this island. You come to a clearing in the brush and find two paths in front of you. You know that one of these paths leads to freedom and the other to certain death, but you don't know which is which. In front of each path stands a man. You know that one of these men is a liar and the other a truth-teller, but you don't know who is who. You are allowed to ask ONE of the men ONE question; the answer to this question will give you the information necessary to choose the right path.* What is the question?
The thing I enjoy about this particular riddle is the fact that the answer isn't cheap or gimmicky. It takes some genuine reasoning to answer it.
*The liar does not necessarily stand in front of the "bad" path, nor does the truth-teller necessarily stand in front of the "good" path; this association is unsystematic.