this is a bit easier than the other ones
this story is about three cowboys being captured by the evil indians. all three cowboys are being tied to totem poles, one behind another, so that the first one only sees the empty prairie in front of him, the second one sees the first cowboy in front of him and the third cowboy sees the other two in front of him.
each of them gets a feather stuck to their hat, but so they can't see the one on their own hat. the indian chief tells them: "our tribe has in total two white feathers and three black feathers. each of you got one of those feathers on your hat. one of you has to make a guess which color the feather on his hat has. if his guess is correct, you all will be set free. if the guess is wrong, you will all be killed."
then everyone fell silent. after a few minutes, the first (front) cowboy suddenly says "i've got a black feather on my hat". he is right and all three are set free.
how did he know?
ps: don't post if you already know the answer
pps: it's a pure logical thing, there's no cheating or other weird stuff involed.