# Yet another paradox **URL:** \ **Category:** Great Debates\ **Created:** [May 10, 2002, 2:47am UTC](https://boards.straightdope.com/t/yet-another-paradox/108218 "2002-05-10T02:47:48Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [May 10, 2002, 2:47am UTC](https://boards.straightdope.com/t/yet-another-paradox/108218/1 "2002-05-10T02:47:48Z")
This showed up in a philosophy class I was taking this semester. The class is over, but I never did figure out how to deal with it. There is a sentence referring to you that says “X does not say that this sentence is true in his or her post discussing this sentence,” where X is your username. By the law of the excluded middle, this sentence is either true or false, but as soon as you commit to one position, you’ve endorsed the other. This looks kinda bleak, doesn’t it? So what do you say, logic-loving dopers? Is this sentence true, or is it false? What does it mean if it’s neither? ---
**Author:** ![knock\_knock](https://avatars.discourse-cdn.com/v4/letter/k/22d042/32.png) [@knock\_knock](https://boards.straightdope.com/u/knock_knock)\ **Post date:** [May 10, 2002, 3:06am UTC](https://boards.straightdope.com/t/yet-another-paradox/108218/2 "2002-05-10T03:06:55Z")
That’s an interesting sentence. ---
**Author:** ![knock\_knock](https://avatars.discourse-cdn.com/v4/letter/k/22d042/32.png) [@knock\_knock](https://boards.straightdope.com/u/knock_knock)\ **Post date:** [May 10, 2002, 3:10am UTC](https://boards.straightdope.com/t/yet-another-paradox/108218/3 "2002-05-10T03:10:28Z")
Beginning at t=4:06 am 5-10-2002 GMT, that sentence is true. ---
**Author:** ![knock\_knock](https://avatars.discourse-cdn.com/v4/letter/k/22d042/32.png) [@knock\_knock](https://boards.straightdope.com/u/knock_knock)\ **Post date:** [May 10, 2002, 3:11am UTC](https://boards.straightdope.com/t/yet-another-paradox/108218/4 "2002-05-10T03:11:38Z")
Beginning at t=4:10 am 5-10-2002 GMT (and continuing indefinitely thereafter), that sentence is false. ---
**Author:** ![knock\_knock](https://avatars.discourse-cdn.com/v4/letter/k/22d042/32.png) [@knock\_knock](https://boards.straightdope.com/u/knock_knock)\ **Post date:** [May 10, 2002, 3:16am UTC](https://boards.straightdope.com/t/yet-another-paradox/108218/5 "2002-05-10T03:16:02Z")
What was the truth value of that sentence before 4:06 am 5-10-2002 GMT? Then it was like that famous “The present King of France is bald” proposition. I don’t remember how the solution to that one goes, though. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [May 10, 2002, 3:28am UTC](https://boards.straightdope.com/t/yet-another-paradox/108218/6 "2002-05-10T03:28:48Z")
If there is no King of France at the moment, I say that sentence is false. ---
**Author:** ![dysurian](https://avatars.discourse-cdn.com/v4/letter/d/c5a1d2/32.png) [@dysurian](https://boards.straightdope.com/u/dysurian)\ **Post date:** [May 10, 2002, 3:52am UTC](https://boards.straightdope.com/t/yet-another-paradox/108218/7 "2002-05-10T03:52:34Z")
I would be inclined to say that the question of the king of France (or the statement which becomes false as soon as it is proven true) are best left at “paradox” and not “true” or “false.” It doesn’t make sense to force yourself to assign a truth value to an empty set like that. ---
**Author:** ![Left\_Hand\_of\_Dorkness](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/left_hand_of_dorkness/32/7156_2.png) [@Left\_Hand\_of\_Dorkness](https://boards.straightdope.com/u/Left_Hand_of_Dorkness)\ **Post date:** [May 10, 2002, 4:06am UTC](https://boards.straightdope.com/t/yet-another-paradox/108218/8 "2002-05-10T04:06:50Z")
I would consider a sentence identical to the one we’re examining to be true; you’ll note that the sentence we’re examining contains the word “zebra” seventeen times. More precisely, there are ways to discuss a sentence that don’t involve discussing its truth or falsehood. If you want a paradox, I think you need to rephrase the OP: “When X eventually commits to an absolute position regarding truth of this sentence, X will not declare the sentence to be always true.” where “an absolute position” is defined as either “always true” or “always false.” Logic majors can gussy that correction up with proper jargon, but I think the basic principle applies: As long as I’m allowed to discuss such a sentence without committing to its truth or falsehood, then such a sentence can be true as long as I don’t commit to a position regarding its truth in the post in which I discuss it. Interestingly, such a sentence can’t be false: if I commit to a position regarding such a sentence’s truth, then we get a paradox. One final note. Your sentence does not, of course, contain the word “zebra.” The fact that I incorrectly suggested that it does in no way affects the sentence’s truth; all it does is satisfy this post’s need to discuss the sentence. Daniel