# Thread: A liar says he tells truth. So he is a liar. But he just told he tells truth.Solution

1. ## A liar says he tells truth. So he is a liar. But he just told he tells truth.Solution

A liar says I am a truthteller. But he is a liar. He can't be a truthteller. He is a liar. But the liar said he is a truth teller. We have reached a contradiction.

What is the solution?

2. ## Re: A liar says he tells truth. So he is a liar. But he just told he tells truth.Solu

Why is a liar saying he is a truth-teller a paradox? Since he is a liar what he is in NOT true- he is not a truth-teller.

IF "liar" and "truth-teller" are the only options then it would be a "paradox" for a liar to say "I am NOT a truth-teller" or for a truth-teller to say "I am a liar".

3. ## Re: A liar says he tells truth. So he is a liar. But he just told he tells truth.Solu

How have you reached a contradiction. You already pointed out that he lied. His statement was a lie. There is no contradiction. And what sort of "solution" are you seeking?

4. ## Re: A liar says he tells truth. So he is a liar. But he just told he tells truth.Solu

Originally Posted by SlipEternal
How have you reached a contradiction. You already pointed out that he lied. His statement was a lie. There is no contradiction. And what sort of "solution" are you seeking?
Let me rephrase it how I reached a contradiction. It is called Liar paradox.

"'I said in my alarm, Every man is a liar!' Is David telling the truth or is he lying? If it is true that every man is a liar, and David's statement, "Every man is a liar" is true, then David also is lying; he, too, is a man. But if he, too, is lying, his statement: "Every man is a liar," consequently is not true. Whatever way you turn the proposition, the conclusion is a contradiction. Since David himself is a man, it follows that he also is lying; but if he is lying because every man is a liar, his lying is of a different sort."

5. ## Re: A liar says he tells truth. So he is a liar. But he just told he tells truth.Solu

Originally Posted by x3bnm
Let me rephrase it how I reached a contradiction. It is called Liar paradox.
That is very different from what you stated. The Liar's Paradox is another well known example of paradox through self reference.

6. ## Re: A liar says he tells truth. So he is a liar. But he just told he tells truth.Solu

Originally Posted by x3bnm
> > > A liar says I am a truthteller. < < < But he is a liar. He can't be a truthteller. He is a liar. But the liar said he is a truth teller. We have reached a contradiction.

What is the solution?
x3bnm, your English did not communicate what you intended. What I emphasized above means that a liar said that you, x3bnm, are a truthteller. That is not what you meant.
You needed to have put what the liar said in quotes. (I did not realize this until I read your post to the end.)

Here is what you should have posted:

A liar says, "I am a truthteller."

7. ## Re: A liar says he tells truth. So he is a liar. But he just told he tells truth.Solu

Originally Posted by greg1313
x3bnm, your English did not communicate what you intended. What I emphasized above means that a liar said that you, x3bnm, are a truthteller. That is not what you meant.
You needed to have put what the liar said in quotes. (I did not realize this until I read your post to the end.)

Here is what you should have posted:

A liar says, "I am a truthteller."
Sorry for the miscommunication from my part.

8. ## Re: A liar says he tells truth. So he is a liar. But he just told he tells truth.Solu

A and B always lie. They are chatting between themselves.
A says, 'You are a truth-teller.'
B replies, 'I'm not a liar.'

Is there a word for such situations?