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naturalplastic
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22 Nov 2017, 10:48 am

The statement "this statement is false" is self referential, and it is only self referential, and nothing but self referential. It doesn't describe anything other than its own content, which is solely content about its own content, which is only about its own content, and so on.

Consider the opposite statement "this statement is true".

Is that statement "true", or "false"?

You could declare "this statement is true" to be true, that it is true, that it is true, that..... . Or you could declare it to be false...that its true. Either way there would be no contradiction. No seeming "paradox".

So "this statement is true" would seem to be unlike its negative near twin, and to be like most statements (like "all crows are black"), in that in principle it could be judged as being one or the other (as being true, or as being false). So which thing is it?

Is "this statement is true" true, or false?

The fact is that the statement is meaningless. And stating that is true, or stating that is false, are both also equally meaningless.

Is it "true" that the content of the statement "this statement is true" is true? Or is it false? Its meaningless either way.

So the negative version of the statement is also meaningless. So its not a paradox because there is no contradiction because you have to have meaning in order to have a contradiction in meaning.

"This statement is false" is not a contradiction because it doesn't mean anything anyway.



thinkinginpictures
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23 Nov 2017, 10:56 am

naturalplastic wrote:
The statement "this statement is false" is self referential, and it is only self referential, and nothing but self referential. It doesn't describe anything other than its own content, which is solely content about its own content, which is only about its own content, and so on.

Consider the opposite statement "this statement is true".

Is that statement "true", or "false"?

You could declare "this statement is true" to be true, that it is true, that it is true, that..... . Or you could declare it to be false...that its true. Either way there would be no contradiction. No seeming "paradox".

So "this statement is true" would seem to be unlike its negative near twin, and to be like most statements (like "all crows are black"), in that in principle it could be judged as being one or the other (as being true, or as being false). So which thing is it?

Is "this statement is true" true, or false?

The fact is that the statement is meaningless. And stating that is true, or stating that is false, are both also equally meaningless.

Is it "true" that the content of the statement "this statement is true" is true? Or is it false? Its meaningless either way.

So the negative version of the statement is also meaningless. So its not a paradox because there is no contradiction because you have to have meaning in order to have a contradiction in meaning.

"This statement is false" is not a contradiction because it doesn't mean anything anyway.


It is meaningful in the way that it is a logical way of coming to the conclusion that you cannot prove a negative. You can't prove that something isn't. You can only prove there IS something.

By stating "this statement is true" is self-evident. If it says it is true, it IS true. Only when you add up more values, like "Trump is dumb is true" you have to explain why.

It is an entirely different matter when you are going to have a negative statements. "This statement is false" is self-contradicting, because if the statement really is false, it is true. And if the statement that it is false, is true, it is false. And so on.

There is a reason why I picked this sentence. You can't do it with the "this statement is true", only "this statement is false" is a contradiction.



naturalplastic
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23 Nov 2017, 11:57 am

Utter nonsense.

You picked the statement for the same reason that everyone else in the last 3000 years picked it, because it SEEMS to be a contradiction. You dont need to tell us that water is wet. We know that.

What I am saying is the the way out of this paradox that bothers you so much is to do something different than what has been done in the last 3000 years, and that's to consider the statement's opposite.

The statement "this statement is true" is self referential, referential only to its own empty content. Empty content is meaningless, and thus cant be classified as either true or false. Its like trying to determine whether or not a belch is true or false. True and false don't apply to a belch.

Saying "it is meaningful insofar that it shows how you cant prove a negative" is nonsense. It has nothing to do with the adage that "you cant prove a negative" because that adage only applies to statements that refer to things other the statement itself. Statements like "Trump is whatever" or "the earth is being visited by alien space craft" refer to things outside the statement (Trump and the world or UFOs etc).

IF you find one real UFO crashed in the swamp then you have proven that alien space craft really are visiting us. But you cant really disprove the assertion because you cant show that there wasn't some one real UFO that visited and got away without being detected.

Saying "this statement is true" is "true" because "it says so" is nonsense. True about what? About the fact that it is true? True about the fact that it is true, about the fact that is true...about what? True about the fact that it is true about the fact that it is true, about the fact......ad infintum. Its a meaningless statement.

Further you could just as easily declare the statement "this statement is true" to be FALSE. Like the first statement there is no self-contradiction. It makes just as much sense to say "this statement is true" is false, as it does to say that this statement is true is true. Further where is the evidence either way? Both are self referential statements. Neither statement refers to any reality in which can gather evidence.

Likewise the third statement "this statement is false" is also nothing but self referential, and therefore meaningless. Unlike the first two statements it seems to be a contradiction. But since like the first two statements it is meaningless it cannot be a contradiction because you have to have meaning before you can have either contradiction or consistency.



Last edited by naturalplastic on 23 Nov 2017, 1:03 pm, edited 1 time in total.

thinkinginpictures
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23 Nov 2017, 12:37 pm

naturalplastic wrote:
yUtter nonsense.

You picked the statement for the same reason that everyone else in the last 3000 years picked it, because it SEEMS to be a contradiction. You dont need to tell us that water is wet. We know that.

What I am saying is the the way out of this paradox that bothers you so much is to do something different than what has been done in the last 3000 years, and that's to consider the statement's opposite.

The statement "this statement is true" is self referential, referential only to its own empty content. Empty content is meaningless, and thus cant be classified as either true or false. Its like trying to determine whether or not a belch is true or false. True and false don't apply to a belch.

Saying "it is meaningful insofar that it shows how you cant prove a negative" is nonsense. It has nothing to do with the adage that "you cant prove a negative" because that adage only applies to statements that refer to things other the statement itself. Statements like "Trump is whatever" or "the earth is being visited by alien space craft" refer to things outside the statement (Trump and the world or UFOs etc).

IF you find one real UFO crashed in the swamp then you have proven that alien space craft really are visiting us. But you cant really disprove the assertion because you cant show that there wasn't some one real UFO that visited and got away without being detected.

Saying "this statement is true" is "true" because "it says so" is nonsense. True about what? About the fact that it is true? True about the fact that it is true, about the fact that is true...about what? True about the fact that it is true about the fact that it is true, about the fact......ad infintum. Its a meaningless statement.

Further you could just as easily declare the statement "this statement is true" to be FALSE. Like the first statement there is no self-contradiction. It makes just as much sense to say "this statement is true" is false, as it does to say that this statement is true is true. Further where is the evidence either way? Both are self referential statements. Neither statement refers to any reality in which can gather evidence.

Likewise the third statement "this statement is false" is also nothing but self referential, and therefore meaningless. Unlike the first two statements it seems to be a contradiction. But since like the first two statements it is meaningless it cannot be a contradiction because you have to have meaning before you can have either contradiction or consistency.


I am doing something different to solve the paradox. Just not your way of considering it's opponent, but saying that our paradox is only a mental construction.

It is like those who say that mathematics is all in the nature. No it is not. Nature doesn't "know" mathematics, nature knows nothing. The shapes of nature, ie. the fractals or mandelbrot set is not "nature doing maths". It is nature doing something that repeats its previous part locally, and we as humans see a pattern emerge, because our brains tell us there is a pattern.

The way out of the paradoxes is to consider our brains fooling us to believe we see shapes where there are none or paradoxes where there are none. "This sentence is false" is neither true or false, but wrong. It is as wrong a sentence as combining different words and letters in a random order and claim it as a sentence. It is nothing more, nothing less.

The universe is not fooling us, not even when we do quantum mechanics. We fool ourselves.



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23 Nov 2017, 3:03 pm

It isn't a valid statement, or a statement at all. Not everything that can be said or written is a valid statement, even when it's grammatically in the form of a statement.

thinkinginpictures wrote:
I have a paradox that I can't seem to find the solution to.
(edit: Perhaps I should mention it is Gödel's Incompleteness Theorem's reference to the Liar-paradox)

https://en.wikipedia.org/wiki/G%C3%B6de ... s_theorems

I googled it many times, trying to get rid of the problem, but I couldn't find any solutions:

---
The following sentence is false:
The above sentence is true!
---

Or simplified:

"This sentence is false!"
-

How do I logically make sense of this paradox, without creating other paradoxes? How do I figure out which of the two sentences are the correct one, and which one isn't?

If there is no solution to it, is the paradox itself wrong? Does the universe itself contain any such paradox or anything similar?

If there are indeed truely such paradoxes, what do we do to explain the universe? Must we not have a fully explainable universe?


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billegge
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23 Nov 2017, 7:41 pm

thinkinginpictures wrote:
I have a paradox that I can't seem to find the solution to.
(edit: Perhaps I should mention it is Gödel's Incompleteness Theorem's reference to the Liar-paradox)

https://en.wikipedia.org/wiki/G%C3%B6de ... s_theorems

I googled it many times, trying to get rid of the problem, but I couldn't find any solutions:

---
The following sentence is false:
The above sentence is true!
---

Or simplified:

"This sentence is false!"
-

How do I logically make sense of this paradox, without creating other paradoxes? How do I figure out which of the two sentences are the correct one, and which one isn't?

If there is no solution to it, is the paradox itself wrong? Does the universe itself contain any such paradox or anything similar?

If there are indeed truely such paradoxes, what do we do to explain the universe? Must we not have a fully explainable universe?


No content is given which can be true or false.


thinkinginpictures wrote:
If there are indeed truely such paradoxes, what do we do to explain the universe? Must we not have a fully explainable universe?


Contradictions do not exist.

http://aynrandlexicon.com/lexicon/contradictions.html



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23 Nov 2017, 7:49 pm

congratulations, you broke language.

also: Read Goedel, Escher, Bach to understand how a formal system (in this case language) can be used to break it, given that it's strong enough to be self-referential.
works also with math.

does it mean anything, outisde of logic and AI? meh.

http://aynrandlexicon.com/lexicon/contradictions.html

also: don't take dogma from ayn rand. she's really not that great a thinker. she just got popular with mediocre thinkers who love to think they're misunderstood geniuses, itself a romantic era concept we owe to Kant and Hegel.


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23 Nov 2017, 8:21 pm

shlaifu wrote:
also: don't take dogma from ayn rand. she's really not that great a thinker. she just got popular with mediocre thinkers who love to think they're misunderstood geniuses, itself a romantic era concept we owe to Kant and Hegel.


Thanks, I will keep that in mind.

You may want to take a closer look at Ayn Rand because she never supported dogma.

Dogma
http://aynrandlexicon.com/lexicon/dogma.html

"Objectivism is its own protection against people who might attempt to use it as a dogma."



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24 Nov 2017, 9:55 am

billegge wrote:
shlaifu wrote:
also: don't take dogma from ayn rand. she's really not that great a thinker. she just got popular with mediocre thinkers who love to think they're misunderstood geniuses, itself a romantic era concept we owe to Kant and Hegel.


Thanks, I will keep that in mind.

You may want to take a closer look at Ayn Rand because she never supported dogma.

Dogma
http://aynrandlexicon.com/lexicon/dogma.html

"Objectivism is its own protection against people who might attempt to use it as a dogma."



yeah... rand's rationalism is her dogma.


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09 Dec 2017, 6:10 pm

Since long this paradox has been analyzed in mathematical logic, namely as a basis of the proof of the incompleteness theorem, and what was discovered, as surprising as it may sound, is the following.
In the sentence, "this sentence is false", the problem is neither about the concept of "sentence" (as formulas can be described as a kind of mathematical systems), nor about self-reference (it is actually possible for a formula to quote itself, this quotation included !), but about the truth predicate over the class of formulas (the qualification for a formula as true or false) as soon as the formula in question is not explicitly written in full as a sub-formula in the right place of the main formula, but only given as an object (mathematical system).
The proof of the incompleteness is based on the established possibility for a formula to quote itself, so we can form a formula which says "This formula is unprovable in System X" where X is some given axiomatic system of arithmetic, or of set theory for its ability to prove formulas of arithmetic as particular cases. Then after some work this self-referencing formula (but we only qualify it as self-referencing when looking at it on a high level, as it is but a super abbreviation of some lengthy formula of pure arithmetic) turns out to be logically equivalent to the formula "System X does not lead to contradiction"
If you wonder the status of another formula saying "This formula is provable in System X" the answer is known !
Namely such a formula is actually provable, and its proof comes as a corollary of the Incompleteness theorem, called Löb's theorem.
I wrote a page about it : http://settheory.net/model-theory/incompleteness



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10 Dec 2017, 1:17 am

I've run across this one before, mainly in how it supposedly destroyed Logicism (Gottlob Frege's the idea that math is a subset of logic). It's one of those problems I find really tedious and haven't examined much on a formal or academic level because it involves extended research of definitions to figure out what ideas are actually destroyed by this sentence, or two sentences, being writable or utterable.

I remember in a theism debate someone, I think AG, brought up the concept of a square circle (ie. in reference to questions like 'Could God draw a square circle') as a good example of a linguistic absurdity which was grammatically possible but held no valid meaning. It reminds me of something which I think is intuitively obvious, ie. that typical written and spoken language was never intended to be a perfectly consistent set of logical operators and it would be very strange if it did pass any sort of test for perfect logical consistency being that's somewhat orthogonal to the original goal of language which is meant to carry truth as much as its meant to carry BS, poetry, propaganda, and anything else you can imagine one person saying to another. Past that I don't really know. It might very well be that there's plenty of math that gives untestable answers but I'd also think there's plenty of logic that can create absurdities, even properly applied, if it doesn't doesn't check in with physical reality on a routine basis.


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10 Dec 2017, 12:10 pm

techstepgenr8tion wrote:
I remember in a theism debate someone, I think AG, brought up the concept of a square circle (ie. in reference to questions like 'Could God draw a square circle') as a good example of a linguistic absurdity which was grammatically possible but held no valid meaning.


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10 Dec 2017, 12:38 pm

Could God build a boulder so big that even he (God) couldn't lift it?



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10 Dec 2017, 5:17 pm

naturalplastic wrote:
Could God build a boulder so big that even he (God) couldn't lift it?


I'm not familiar with anyone called "God".



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10 Dec 2017, 5:31 pm

techstepgenr8tion wrote:
I've run across this one before, mainly in how it supposedly destroyed Logicism (Gottlob Frege's the idea that math is a subset of logic). It's one of those problems I find really tedious and haven't examined much on a formal or academic level because it involves extended research of definitions to figure out what ideas are actually destroyed by this sentence, or two sentences, being writable or utterable.

The point of the incompleteness theorem was to focus on what can be exactly done, in the completely rigorous framework of mathematical logic, freed from all the usual fuzziness of ordinary language. Its presentations may look like something based on ordinary language just because that is the most convenient way of introducing it and giving an intuition of the main ideas of how it works, so unless you undertake to check the details yourself, all you can do apart from fleeing the topic is to trust the experts for having checked the correctness of the details underlying these introductive presentations that you can see.

For the question of what ideas are actually destroyed by this theorem: it exactly destroys the idea of an algorithmic decidability (ability to correctly prove or refute by a single algorithm) of all first-order formulas of arithmetic (formulas using symbols of 0,1,+,⋅, =, connectives and quantifiers over variables ranging in the set of natural numbers).

However, there is another version of logicism that is proven by another theorem which is also from Godel, that is the Completeness Theorem : we have a known algorithm which is able to prove any true consequence of any given axiomatic system written in first-order logic, where "true consequence" means a formula that is true in all models of the given theory (all possible systems of objects where all given axioms are true).

Now if we put together both theorems which naively seem in conflict with each other, what we can conclude from them is that for any axiomatic theory aimed to describe arithmetic there exists a system of objects, called a non-standard model of arithmetic, which behaves pretty much like the true set of natural numbers in the sense of obeying the given axiomatic description, but yet does not have all the same properties expressible in first-order logic. I wrote in more details some lessons I could draw from the study of the foundations of mathematics.



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10 Dec 2017, 5:55 pm

First thank you for the well-built synopsis.

spoirier wrote:
The point of the incompleteness theorem was to focus on what can be exactly done, in the completely rigorous framework of mathematical logic, freed from all the usual fuzziness of ordinary language. Its presentations may look like something based on ordinary language just because that is the most convenient way of introducing it and giving an intuition of the main ideas of how it works, so unless you undertake to check the details yourself, all you can do apart from fleeing the topic is to trust the experts for having checked the correctness of the details underlying these introductive presentations that you can see.

It's a big enough topic to need very in-depth devotion to following its consequences. I'm 38 now, maybe in my fifties I'll find the free resources to dedicate to this one but for the moment I have my plate full of similarly complex problems that I think need attention just as urgently. For me right now in particular it's shaking apart a certain naive corner of reductive materialism that seems to automatically assume that we aren't in a universe that's absolutely brimming with mind even if it might be a sort of animistic mind-without-a-God or perhaps something stranger still.

Regardless I do try to appreciate and respect people who are doing the digging on topics that I can't attend to and I try keep my radar accurately tuned to see who is on the right track with their work even if I'll admit my radar for that is still a work in progress.

spoirier wrote:
For the question of what ideas are actually destroyed by this theorem: it exactly destroys the idea of an algorithmic decidability (ability to correctly prove or refute by a single algorithm) of all first-order formulas of arithmetic (formulas using symbols of 0,1,+,⋅, =, connectives and quantifiers over variables ranging in the set of natural numbers).

However, there is another version of logicism that is proven by another theorem which is also from Godel, that is the Completeness Theorem : we have a known algorithm which is able to prove any true consequence of any given axiomatic system written in first-order logic, where "true consequence" means a formula that is true in all models of the given theory (all possible systems of objects where all given axioms are true).

Now if we put together both theorems which naively seem in conflict with each other, what we can conclude from them is that for any axiomatic theory aimed to describe arithmetic there exists a system of objects, called a non-standard model of arithmetic, which behaves pretty much like the true set of natural numbers in the sense of obeying the given axiomatic description, but yet does not have all the same properties expressible in first-order logic. I wrote in more details some lessons I could draw from the study of the foundations of mathematics.

This is where I think the presenters of the lecture I listened to might have done me a disservice in that they highlighted the historical event of Bertrand Russel sending that sentence to Frege before his thesis on Logicism was published. What digging I did at the time was my attempt to deal with a problem I saw with what they were saying - ie. I thought math as a subset of logic was a brilliant observation but when it was suggested that this idea was squashed by Godel's findings of unprovable math I couldn't connect the two. Listen to a head-strong enough metaphysical philosopher long enough and you'll see them overshoot actual evidence by a mile or more and come up with insane ideas because they're calculating on what they think should be there rather than considering just how many variables that they don't know (to which the compound result of those variables is a deal breaker almost all of the time).

I was stuck asking myself in that case - are they actually meaning 'logic' in a much more special, nuanced, and subsidiary case than what I'm used to hearing and thinking of? I think that's where the can of worms just got too big for me.


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