The Fork in the Road

A traveler finds himself on an island inhabited by two opposing tribes. Members of one tribe must always tell the truth, while members of the other always lie. He comes to a fork in the road and has to ask a bystander which path he should take to reach a nearby village. The traveler has no way of finding out whether the bystander is a liar or a truth teller. What question should he ask to determine which path to take?