Liar ID
Logic
Level
1
Honest men always tell the truth and liars always lie. What can be said about these men?
(Note that "one of two of us" is used in the sense of "only one of the two of us".)
Clark is the only honest one
It's impossible to tell
Lewis is the only honest one
They are both honest
They are both liars
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
We have 4 cases: Both Honest, Both Liars, Lewis is the only liar, Clark is the only liar.
Case 1 : Both Honest
If both of them are honest, then when Clark says that they are both Liars he must be telling the truth. If he's telling the truth then he's not a liar like he says. Case 1 is impossible.
Case 2 : Both Liars
If both of them are liars, then when Clark says that they are both Liars he must be lying. However, we already know that his statement is true. Case 2 is impossible.
Case 3 : Lewis is the only liar
If Lewis is the only liar, then when Clark says that they are both Liars he must be telling the truth. However, we already know that his statement is false. Case 3 is impossible.
Case 4 : Clark is the only liar
If Clark is the only liar, then when Clark says that they are both Liars, his statement must be false. Then he is indeed a liar. Lewis is telling the truth since there is only liar (by the givens of Case 4). This makes him honest. Case 4 works.
Lewis is the only honest man.