Logic Puzzle: The Teacher

Here is a puzzle that we can call "The Teacher":

• Suppose that Renna is looking at Bob.
• Also suppose that Bob is looking at Marley.
• Renna is a teacher and Marley is not a teacher.
• It is not known whether Bob is a teacher or not a teacher.

Is a teacher looking at a non-teacher?

Reveal Answer

Yes, a teacher is looking at a non-teacher.

• Here is the setup: R -> B -> M
• Bob is either a teacher or not a teacher.
• Suppose that Bob is a teacher. If so, then a teacher (Bob) is looking at a non-teacher (Marley)
• Suppose that Bob is not a teacher. If so, then a teacher (Renna) is looking at a non-teacher (Bob)
• Therefore, a teacher is looking at a non-teacher.