a riddle

This is a very old riddle. He asks either man what the other one would say. Let's say the correct path is to the left.

He asks the liar, who lies and says the truthteller would say the path is to the right.

He asks the truthteller, who tells the truth and says the liar would say the path is to the right.

Then he does the opposite of what he's just been told.

And so he knows the correct path, but how does he know which of them is lying?

Oops. Well, at least he gets where he's going.

all u do is come up to one guy,
and say "are u a human?", if he says no,
obviously he is the liar. then u ask him another question.
u say "which path should i take?", and then u take the opposite path.

or vice-versa

You ask the 1st person "which one is the right path?" and you ask the 2nd person "what is the first person going 2 say?". If the 1st person says the right path and the 2nd person says the right path, then the 2nd person is the truth teller, the 1st person is the liar and you go left. If the 1st person says the right path and the 2nd person says the left path, then the 2nd is the liar, the 1st the truth teller and you go right. And vice versa.
Very old riddle which also is questioned wrong. it should be "he meets 2 men, 1 always tells lies and the other always tells truths. He can ask 1 question each. What should she ask?"
At least that's how I know it.

Kick 'em in the nuts and ask, "did that hurt?"