The Puzzle
You are at an unmarked intersection. One way is the road to the City of Lies and the other way is the City of Truth.
Citizens of the City of Lies always lie.
Citizens of the City of Truth always speak the truth.
A citizen of one of those cities (you don’t know which) is at the intersection. What question could you ask them to find out the way to the City of Truth?
Citizens of the City of Lies always lie.
Citizens of the City of Truth always speak the truth.
A citizen of one of those cities (you don’t know which) is at the intersection. What question could you ask them to find out the way to the City of Truth?
The Solution
You ask "In which of those two directions do you live?"
A Citizen of the City of Lies will point to the City of Truth
A Citizen of the City of Truth will point to the City of Truth
A Citizen of the City of Lies will point to the City of Truth
A Citizen of the City of Truth will point to the City of Truth