The truth or a lie ? - Solution

You have entered the city !

You asked something like this:

What would your sister tell me if I asked her where this path leads ?

Let’s call the sisters truth and lie.

Let’s imagine that truth is standing for heaven and lie is standing for hell.

If you’d ask truth this question she would tell you what lie would tell you (’hell’), so the total answer would be ‘hell’.

If you’d ask lie this question she would NOT tell you what truth would tell you (’heaven’), so the total answer would be also be ‘heaven’.

Therefore you should take the path from which the sister answers ‘hell’…

This solution was sent in by Morganna the Unholy.

Corey Thurston has a different explanation based on an empirical experiment.

‘My comment is about the “Truth of Lie” riddle. Even after reading the
solution, I still couldn’t figure out how you would know which path
leads to where if you didn’t already know the answer. So with the help
of some friends we reenacted the scenario. I’ve come up with a
different way to explain the solution. You ask the question “What would
your sister say this path led to?”. Whatever answer you get, either
“city” or “forest”, from either the truth teller or the liar it doesn’t
matter, you know that the place that they answered, either “city” or
“forest”, that place is located behind the opposite path then the one
you asked about. I realize this also doesn’t make much sense, so here’s
an example. “What would your sister say the path on the left led to?”
The sister answers, “The forest.” So now you know that no matter what
the path on the right leads to the forest. And if you asked the same
question at another time in another situation and the sister said, “My
sister would say that the path on the left went to the city”, you would
know that the path on the right led to the city. I recommend actually
trying this riddle out with actual people and actual paths (or doors).
Have them pick who is the liar and who is the truth teller and which
door leads to where.

I really enjoy your riddles and can’t wait for more!!’

Here is a sort like problem:

You are heading for RiddleCity and come to a fork in the road with no
signposts. You know that in this area there are only two kinds of
people, liars and truthtellers and that the words grock and grink mean
yes and no but you don’t know which one means yes and which one means
no. A man approaches (either a liar or a truthteller but you can’t tell
them apart). You ask the man one question which he answers either
“Grock” or “Grink” and you know for sure which is the road to
RiddleCity. What question did you ask ?

Solution:

You point to one of the forks and ask, “If I asked you if this was the
the road to RiddleCity, would you say “Grink”. If he says “Grink”, that
is the correct road.

Alternatively, you could ask, “If I asked you if this was the road to
RiddleCity, would you say “Grock”. If he says “Grock”, that is the
correct road.

The sad part is that you still don’t know if the man is a liar or a
truth teller ond whether Grink means or Grock means yes.

Sent in by James J. O’Connor