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Double Liar Paradox (Jourdain's paradox)

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Posted · Report post

its unknowable, possibly just playing with words to make an impossible situation. quite like saying "i am sometimes consistant", it makes no sense and cannot be true - its just bad english.

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Posted · Report post

The lying example doesn't work. Lying and not telling the truth are entirely different. When you lie, you are telling someone something that you believe is incorrect. When you don't tell the truth, you are still able to say what you believe, be incorrect, and not be lying about it.

The tricky part with this paradox is that one statement means nothing without the other. In any event where the statement can stand alone it's not a paradox. Ex: "This statement is false." The statement that is being called false is false, while the entire sentence is true. What is false does not include the word false itself.

The only circular part about this problem is trying to figure it out. The problem itself isn't circular, they both exist at the same time, in the same space.

Even knowing that, I'm having a hard time getting out of the circle. Can anyone else get out of it?

Bravo for your insight on this paradox. You have reminded me of the "lying by omission" statement. If I do not speak the truth, it may still exist, just not in the realm of hearing it being spoken by me. It may also not exist at all, but that is irrelevant. If I state, "I do not speak the truth," but I know the truth and choose not to speak it, does this mean I am lying? I would suggest that instead of considering this to be a circular reasoning problem, consider the dimensions a paradox exists in. The Grecian spoke ill of all Cretans, "All Cretans are liars." When he returned to the island of Crete for a second time, he spoke it again, then added, "All I say is the truth." The only way through this, is to realize that the absolute word ALL is the one thing that can be proven wrong. It does follow that one truthful Cretan can be found. This nullifies the Grecians words that he speaks only the truth. He can be proven to be a liar, without considering his proclamation that he speaks only the truth. In the realm of evidence to the contrary.

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Posted · Report post

This is simply "circular logic" such as "If GOD is all powerful, can HE make a stone so big that HE cannot pick it up?"

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Posted (edited) · Report post

Double Liar Paradox (Jourdain's paradox) - Back to the Paradoxes

This version of the famous paradox was presented by an English mathematician P. E. B. Jourdain in 1913.

The following inscriptions are on a paper:

Back side

Inscription on the other side is true

Face side

Inscription on the other side is not true

Edited by GGJT
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Posted · Report post

The back of the card says the front is true... the front says the back is false, so that would make the back false and the front true.

I am pretty sure that is right

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Posted · Report post

Very, very simple answer. Both sides are false.

The other side is true

= = = = = = = = = = =

The other side is not true

If both false, wouldn't you get:

The other side is not true = the other side is not true

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

The other side is not not true = the other side is true

Back to where we started.

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Posted · Report post

<p>this statement is false<br />

synonym to false is incorrect</p>

<p>this statement is incorrect - if the statement is incorrect is it correct in saying its incorrect not really, because it is incorrect the statement is actually true but by saying its false it is wrong. So its basically the concept of a double negative<br />

false * truth = false</p>

<p><br />

</p>

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Posted (edited) · Report post

only 1side can be true. It can be any side. Both can't be true or both can't be lies at the same time.

Edited by twilight
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Posted · Report post

The sentence on the other side of the card is true that this is false. It is an extreme paradox. There is a point of view.

If you look at the front and then the back, then contradiction comes into play. It means that the back side is true that this is false, but that means both sides are false.

To do this paradox for myself, I used an index card to do it. I came up with "Both sides are false." Any other points?

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Posted · Report post

hey guys think in this way

let

P:

THE SENTENCE ON THE OTHER SIDE OF THIS CARD IS TRUE.

&

Q:

THE SENTENCE ON THE OTHER SIDE OF THIS CARD IS FALSE.

now let us assume P is true which means Q is true.Now Q says P is false ,a contradiction,so P is false.

From above we concluded P is false so it means Q is false(what P says of Q is wrong).Now Q being false says wrong about P.Thus, P is true ,again contradiction.

This way we can start with Q and show that it too has no truth value(neither true nor false).

So, these statements mean nonsense although individually they seem to be logical statements.

Hence, it's all paradoxical

I hope i have conveyed it clearly :-)

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Posted · Report post

In order to truly make this a paradox, you would need to qualify at the beginning that both statements are either true or false.

If both statements are true, it's a paradox because they cannot both be true.

If both statements are false, it's a paradox because they cannot both be false.

There is no such qualifer to this "puzzle"; therefore, it's philosophy.

But it does provoke thought, doesn't it? That's what philosophy does.

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Posted (edited) · Report post

Here are the facts:

Front= "THE SENTENCE ON THE OTHER SIDE OF THIS CARD IS FALSE."

Back= "THE SENTENCE ON THE OTHER SIDE OF THIS CARD IS TRUE."

You can start with either side, it does not matter. Let's use "-n" to specify deniability, and let's start with BACK:

Back = Front = -nBack = -nFront = -n-nBack = -n-nFront = -n-n-nBack = -n-n-nFront = -n-n-n-nBack = -n-n-n-nFront = etc. = etc.

It is an infinite loop of deniability. By starting with BACK, first, assumes truth until the loop cycles back to BACK and deniability begins, infinitely. Starting with FRONT initiates the infinite loop immediately, but intuition of using the FRONT, first, should call the question of "when did this start in the first place?" (there was no beginning, it has always been), because we could have started with BACK initially... See how this works?

Added:

This problem has two flows: a reverse flow


Edited by ACuriousMind
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Posted · Report post

The edit rules are very stringent in this forum, and the edit button did not seem to appear after the "10 min rule". Anyway, from my above post, this is supposed to be the finalized edit:

Added:

This problem tends to have a reverse chronological flow, because the mind attempts to unravel the pattern as soon as the illogical loop is recognized, to find any initializing details.

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Posted · Report post

Whatever value of truth we assign to any of the statements, we'll be trapped in a contradiction. The resolution of such a thing would be to assert that the two statements aren't correlated. It is assumed that the truth value of one statement affects the other one, but we can state that this assumption is wrong and that they are un correlated, and the problem is solved.

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