Descartes' Second Rule vs. Uncertainty

In summary, Descartes' Second Rule of the Direction of the Mind states that only those objects that our mental powers seem adequate to understand should engage our attention. He believes that science, specifically Arithmetic and Geometry, provide certain and indubitable knowledge. He argues that it is better not to study at all than to occupy ourselves with difficult objects that we are unable to distinguish between true and false. He rejects the idea of embracing complete uncertainty and instead suggests trusting only what is completely known and incapable of being doubted. He concludes that in our search for truth, we should focus on objects with the same level of certainty as Arithmetic and Geometry.
  • #1
Mentat
3,960
3
Descartes' Second Rule of the Direction of the Mind is:

Only those objects should engage our attention, to the sure and indubitable knowledge of which our mental powers seem adequate.

He then continues...

Science in it's entirety is true and evident cognition. He is no more learned who has doubts on many matters than the man who has never thought of them; nay he appears to be less learned if he has formed wrong opinions on any particulars. Hence it were better not to study at all than to occupy one's self with objects of such difficulty, that, owing to our inability to distinguish true from false, we are forced to regard the doubtful as certain; for in those matters any hope of augmenting our knowledge is exceeded by the risk of diminishing it. Thus in accordance with the above maxim we reject all such merely probably knowledge and make it a rule to trust only what is completely known and incapable of being doubted.

There is more to it, which I will post if I see it necessary, but that is basically what he is trying to say.

The point of this thread is to determine the level of certainty that is "healthy".

There are those that would have you embrace a complete Uncertainty, in which absolutely nothing is certain (a concept which I believe to be paradoxical, much in the same way as Limitlessness is paradoxical (and this too may be discussed in this thread)). However, there are others who would have you accept some things as certain, and use those things as foundations for progressing in knowledge.

Perhaps there are even some who agree with Descartes' (as quoted above), that we should not trouble ourselves with things that are merely probable, but should stick to that which can be readily demonstrated as factual.
 
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  • #2
BTW, Descartes' talks about Arithmetic and Geometry, calling them the only two fields which we can be certain of, because they make themselves evident to us all of the time. There is a lot more to it, than I am posting, but that's because it (the whole second Rule) fills 1 1/2 book pages.

He concludes by saying this:

But one conclusion now emerges out of these considerations, viz. not, indeed, that Arithmetic and Geometry are the sole sciences to be studied, but only that in our search for the direct road towards truth we should busy ourselves with no object about which we cannot attain a certitude equal to that of the demonstrations of Arithmetic and Geometry.
 
  • #3
what a style this Descartes guy has.really highly inteligent tougths.
i'm like an vilage boy in compare to him.this is how i overtrown uncertainty principle:
E = FX = energy = force times distance
impulse of force = p = Ft = force times time
Et = FXt = pX
Edt+tdE+dEdt=Xdp+pdX+dpdX <=>
(E+dE)dt+tdE=(X+dX)dp+pdX <=>
E'dt+tdE=X'dp+pdX
dp,dX,dE and dt are all proportional
unlike the uncertainty claims:
dEdt>const and dXdp>const reciprocional
 
  • #4
I like most of what he says. I think that he could have mentioned the reliability of scientific-law...
As I see it, science is the reasoned-analysis of the sensations. And since the sensations are mere representations of whatever 'reality' may be, then this means that knowledge is questionable. However, I do not think that this extends to science; for scientific-knowledge is concerned with universal-behaviour, rather than with universal-identity. And I see no rational-argument which can be formulated to state that our perceptions of universal-behaviour are doubtfully-unsure... since the Laws of Physics are absolute.
Where our science is sure and absolute, then that knowledge is considered 'absolute' too. Of course, not all scientific-theories are "sure and absolute"; but for reason to have any impact on anything, we must assume that Einstein - as one example - was absolutely correct. And I can see no reason to argue that he isn't.
Physics is the purest of the sciences, I think. Not perfectly pure, but striving to be so.
Not to cause any more argument; but I think that materialism is the 'knowledge' not to be trusted. But science is largely trustable.
 
  • #5
Originally posted by Lifegazer
I like most of what he says. I think that he could have mentioned the reliability of scientific-law...
As I see it, science is the reasoned-analysis of the sensations. And since the sensations are mere representations of whatever 'reality' may be, then this means that knowledge is questionable. However, I do not think that this extends to science; for scientific-knowledge is concerned with universal-behaviour, rather than with universal-identity. And I see no rational-argument which can be formulated to state that our perceptions of universal-behaviour are doubtfully-unsure... since the Laws of Physics are absolute.
Where our science is sure and absolute, then that knowledge is considered 'absolute' too. Of course, not all scientific-theories are "sure and absolute"; but for reason to have any impact on anything, we must assume that Einstein - as one example - was absolutely correct. And I can see no reason to argue that he isn't.
Physics is the purest of the sciences, I think. Not perfectly pure, but striving to be so.
Not to cause any more argument; but I think that materialism is the 'knowledge' not to be trusted. But science is largely trustable.

So, you agree with Descartes', about relying on what we know to be absolutely true?

What I appreciate about his Second Rule is how he denounces those who would doubt everything that they learn. He says that they might just as well not have learned anything. This coincides with his First Rule (quoted at the end of all of my threads), which shows that the end of study should be the ability to make good judgements in all manners that come before you. If you doubt everything you know, then you will not be able to make sound judgements on any matter that comes before you.
 
  • #6
Originally posted by Mentat

The point of this thread is to determine the level of certainty that is "healthy".

Oh, do you intend to do this with certainty?

Descartes was a fundamentalist after Aristotle's own heart. I'd put him up against a southern Baptist preacher any day of the week. Preferably in a nude mudd wrestling contest. :0)

There are those that would have you embrace a complete Uncertainty, in which absolutely nothing is certain (a concept which I believe to be paradoxical, much in the same way as Limitlessness is paradoxical (and this too may be discussed in this thread)). However, there are others who would have you accept some things as certain, and use those things as foundations for progressing in knowledge.

If you are talking about me, I object. This is not what I believe. When I say acceptance of uncertainty I don't mean throw yourself off the cliff or worship QM! All I'm saying is stop rejecting it as evil, axiomatically false, etc. That you haven't been able to hear me saying that over and over again after all this time reminds me of just how futile it is to argue with a Southern Baptist preacher as well!

Perhaps there are even some who agree with Descartes' (as quoted above), that we should not trouble ourselves with things that are merely probable, but should stick to that which can be readily demonstrated as factual.

The paradox of existence is factual. It constitutes demonstrable emperical evidence. Likewise, the chaos of QM constitutes demonstrable emperical evidence. Neither one proves anything beyond a shadow of a doubt, but I leave such absolute faith in the way things are to Southern Baptists and others.
 
  • #7
Originally posted by Mentat
What I appreciate about his Second Rule is how he denounces those who would doubt everything that they learn.
There are two questions to be asked about existence:-
1. What is it? This is a question of identity.
2. What is it doing? This is a question of behaviour.

I believe that science is largely the study of question-2. It doesn't really address question-1. And question-1 is the thing which most of us cannot agree upon. That's why people who give you answers to question-1 are largely regarded as 'chancers', at the very-best. The answers to this question are extremely diverse. But scientific-law is true. There is a universal-acknowledgment of universal-behaviour.
Some knowledge is fact. Since some knowledge is universal. Exactly like the mathematics and geometry he mentioned. And this includes much scientific-stuff.
That's why I feel justified/comfortable in using scientific-axioms as the basis of my philosophy.
 
  • #8
Please, let me clarify, I'm not talking about the Uncertainty Principle of QM. I was talking about the principle of Uncertainty, where one is supposed to be uncertain of all things (see posts in the thread, "I think therefore I am", fourth page).
 
  • #9
Originally posted by Mentat
Please, let me clarify, I'm not talking about the Uncertainty Principle of QM. I was talking about the principle of Uncertainty, where one is supposed to be uncertain of all things (see posts in the thread, "I think therefore I am", fourth page).

That's just as bizarre and paradoxical as saying it is certain nothing is random... I like it! But that doesn't mean I believe it.
 
  • #10
I apologize for the confusion. It is entirely my fault.

Again, I'm talking about Uncertainty (with a capital "U") as meaning the state of being Uncertain of all things. I was not wishing to discuss QM's uncertainty. Please forgive my blunder, in not making myself more clear.
 
  • #11
No sweat, semantics in philosophy are just too touchy an issue to get upset by the occational mistake.
 
  • #12
One can't go about doubting everything, it's a complete waste of time believe me I've tried, but then the mind needs and craves a concrete framework on which to build knowledge. To me the base is simply God exists and is everything, and everything after that is merely variations of so true as to virtually never require doubt, to high probability truth, to low probability truth, to entirely crackpot products of my own imagination or my crazy friends on physicsforums.com.
 
  • #13
Originally posted by Lifegazer
There is a universal-acknowledgment of universal-behaviour.
And when did you get that 'universal acknowledgment'?
Have you made an agreement not only with all the earthlings, but also all the otherlings around the universe?
 
  • #14
Originally posted by jammieg
One can't go about doubting everything, it's a complete waste of time believe me I've tried, but then the mind needs and craves a concrete framework on which to build knowledge. To me the base is simply God exists and is everything, and everything after that is merely variations of so true as to virtually never require doubt, to high probability truth, to low probability truth, to entirely crackpot products of my own imagination or my crazy friends on physicsforums.com.

Since your argument (taking the existence of God as a fact) contains the assumption that there is no material world in the first place, you have not stopped doubting, but have transformed that doubt in an Absolute Doubt (about the material world).
 
  • #15
Originally posted by heusdens
And when did you get that 'universal acknowledgment'?
Have you made an agreement not only with all the earthlings, but also all the otherlings around the universe?
I trust that the laws of physics are singular.
 
  • #16
Originally posted by wuliheron
That's just as bizarre and paradoxical as saying it is certain nothing is random... I like it! But that doesn't mean I believe it.

I agree that it is paradoxical. In the thread, "I think therefore I am", I related it to the Paradox of Limitlessness (do you see the connection?).
 
  • #17
Greetings !
Originally posted by Descartes
But one conclusion now emerges out of these
considerations, viz. not, indeed, that
Arithmetic and Geometry are the sole
sciences to be studied, but only that
in our search for the direct road
towards truth we should busy ourselves
with no object about which we cannot
attain a certitude equal to that of the
demonstrations of Arithmetic and Geometry.
Well, first of all - there are more mathematical
fields availible today. :wink:
Second, if only the same levels of certainty
as mathematics are required then I'm afraid
I can't press the keyboard anymore because
I'm highly uncertain of its existence...
Something Wu Li said about mud-bath wrestling
comes to mind when I read that stuff.

Live long and prosper.
 
  • #18
Originally posted by Mentat
I agree that it is paradoxical. In the thread, "I think therefore I am", I related it to the Paradox of Limitlessness (do you see the connection?).

Exactly, it seems all paradoxes either succumb to rational explanations or are eventually reduced to variations of the Liar's Paradox or the Sorites Heap Paradox. Either they explicitely defy explanation according to our current understanding or they contain vague terms like infinity or indeterminacy. The paradox of existence, can be described using either paradox.
 
  • #19
Originally posted by drag
Greetings !

Well, first of all - there are more mathematical
fields availible today. :wink:
Second, if only the same levels of certainty
as mathematics are required then I'm afraid
I can't press the keyboard anymore because
I'm highly uncertain of its existence...
Something Wu Li said about mud-bath wrestling
comes to mind when I read that stuff.

Live long and prosper.

According to Descartes' reasoning, it seems that your doubt of your own existence makes you just as one who doesn't exist (or something like that). IOW, your existence loses meaning when you start to doubt it.
 
  • #20
Originally posted by wuliheron
Exactly, it seems all paradoxes either succumb to rational explanations or are eventually reduced to variations of the Liar's Paradox or the Sorites Heap Paradox. Either they explicitely defy explanation according to our current understanding or they contain vague terms like infinity or indeterminacy.

Good point.

The paradox of existence, can be described using either paradox.

What paradox of existence? :wink:

Actually, this is an important point. You say that all paradoxes can be either explained, or reduced to the same kind of paradox as the Liar's paradox. However, I see no paradox of existence that even resembles the Liar's paradox. Yes, I understand that you use "paradox" to mean "inexplicable" usually, and I may or may not agree with that, but I don't see any kind of self-contradiction in existence, and the Liar's paradox is that kind of paradox (the self-contradictory kind).
 
  • #21
Originally posted by Mentat
Good point.



What paradox of existence? :wink:

Actually, this is an important point. You say that all paradoxes can be either explained, or reduced to the same kind of paradox as the Liar's paradox. However, I see no paradox of existence that even resembles the Liar's paradox. Yes, I understand that you use "paradox" to mean "inexplicable" usually, and I may or may not agree with that, but I don't see any kind of self-contradiction in existence, and the Liar's paradox is that kind of paradox (the self-contradictory kind).

Existence is apparently vague and explicite simultaniously. There is no clear explanation for existence, no clear proof of the specific validity or disposition of existence. Yet there is evidence in Quantum Mechanics, for example, that a cat can somehow be both alive and dead simultaneously. In other words, that Existence cannot be proven to be true. This is a variation of the Liar's Paradox which can be rephrased as Existence is false. If true, then the statement contradicts its own existence. If false, then the statement again contradicts itself.
 
  • #22
Originally posted by wuliheron
Existence is apparently vague and explicite simultaniously.

"Existence is vague"? vagueness is a possible attribute of our descriptions, not of "existence". You could probably say that the concept of existence is vague, but in order to say that existence itself is vague, you would need to be much more specific in your use of the word... which is a nice irony (not a paradox, btw).

There is no clear explanation for existence

Agreed, but that does not pose a paradox.

no clear proof of the specific validity or disposition of existence.

A proof can be provided for arguments or mathematical relations (i.e., well defined assertions), not about "disposition". Also, what would be the "validity" of existence?

Yet there is evidence in Quantum Mechanics, for example, that a cat can somehow be both alive and dead simultaneously.

Which contradicts nothing you have said so far. No paradox there.

In other words, that Existence cannot be proven to be true.

The phrase in italics doesn't make sense. As in the case of "proof", the concept of "truth" also applies to descriptions and statements, "existence" is none of them.

The case is similar to saying "archeology cannot be proven to be red".

This is a variation of the Liar's Paradox which can be rephrased as

What are you referring to with "This"?

Existence is false. If true, then the statement contradicts its own existence.

OK so far,

If false, then the statement again contradicts itself.

Not at all. In order to embed some meaning on the phrase

"Existence is false"

we need to twist the meaning and applicability of "false". The only sensible way to do it (that vaguely resembles the intent of the rest of your post) would be to interpret it as "existence can not be verified" or maybe "existence cannot be explained", which are not self-referential statements, and both can perfectly well be false without contradicting themselves.
 
  • #23
Originally posted by ahrkron
"Existence is vague"? vagueness is a possible attribute of our descriptions, not of "existence". You could probably say that the concept of existence is vague, but in order to say that existence itself is vague, you would need to be much more specific in your use of the word... which is a nice irony (not a paradox, btw).

Sorry, but a cat being both alive and dead at the same time is not axiomatically an indication our concepts are vague. Existence is vague and whether or not this is merely our conceptual limitations or the actual reality is debatable.

Agreed, but that does not pose a paradox.

It poses a mystery, just as paradox does.

A proof can be provided for arguments or mathematical relations (i.e., well defined assertions), not about "disposition". Also, what would be the "validity" of existence?

Disposition refers to a physical property or tendency as much as an emotional state. Thus it covers all the bases. As for validity, that refers to what we perceive.

quote:
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In other words, that Existence cannot be proven to be true.
--------------------------------------------------------------------------------

The phrase in italics doesn't make sense. As in the case of "proof", the concept of "truth" also applies to descriptions and statements, "existence" is none of them. The case is similar to saying "archeology cannot be proven to be red".

Are you saying that to say you exist is not a description? If so, what is existence if not nonexistence? To say I exist is a description, to say Santa doesn't exist is to say something. To say existence is valid, true, worthwhile, etc. is to say something.

we need to twist the meaning and applicability of "false". The only sensible way to do it (that vaguely resembles the intent of the rest of your post) would be to interpret it as "existence can not be verified" or maybe "existence cannot be explained", which are not self-referential statements, and both can perfectly well be false without contradicting themselves.

Truth and falsehood are not the same thing as existence, that's why we have separate words for them.
 
  • #24
Originally posted by wuliheron
Originally posted by ahrkron Agreed, but that does not pose a paradox.

It poses a mystery, just as paradox does.
Sure. They both produce a state of mind that we tag as "mystery". That does not imply they are the same (both apples and blood are red, but blood is not apples).

Disposition refers to a physical property or tendency as much as an emotional state.

Yes and, as such, it does not make sense that you "prove it". You can prove that a configuration (or disposition) has some specific attributes, or that a system/person/thing has a given configuration.

Maybe instead of "there's no clear proof of the disposition of existence" you meant "there's no clear proof that the disposition of existence has to be as it is" or something of that sort. I frankly cannot tell what was your intent.

As for validity, that refers to what we perceive.

Again, you were referring to the "proof of the validity of existence". What do you mean "the validity of existence", and what would you consider a "proof" for it?

Are you saying that to say you exist is not a description?

To say you exist is a description, whereas
existence is not.

To say I exist is a description, to say Santa doesn't exist is to say something.

yes, because the predicates can be applied to the subjects, and the resulting phrase makes enough sense to be tested and classified as true or false.

To say existence is valid, true, worthwhile, etc. is to say something.

"worthwhile" works fine. "True" and "valid", on the other hand, make ill-defined phrases.
"Existence is valid", "existence is true" are not well defined. They do evoke some mental images, but they are far from being clear statements.

Truth and falsehood are not the same thing as existence, that's why we have separate words for them. [/B]

I'm missing your point here.
 
  • #25
quote:
Disposition refers to a physical property or tendency as much as an emotional state.
--------------------------------------------------------------------------------

Yes and, as such, it does not make sense that you "prove it". You can prove that a configuration (or disposition) has some specific attributes, or that a system/person/thing has a given configuration.

Maybe instead of "there's no clear proof of the disposition of existence" you meant "there's no clear proof that the disposition of existence has to be as it is" or something of that sort. I frankly cannot tell what was your intent.

You are not making sense. We Can prove the disposition of water is to freeze below a certain temperature, we Can prove a lion's disposition is to hunt, etc. Thus far we have proven existence may not predate the big bang and may have end at some point in the distant future, but its disposition remains mysterious.

Again, you were referring to the "proof of the validity of existence". What do you mean "the validity of existence", and what would you consider a "proof" for it?

Emperical evidence for a TOE would be nice. More than likely such evidence would have to be statistical in nature.

quote:
--------------------------------------------------------------------------------
Are you saying that to say you exist is not a description?
--------------------------------------------------------------------------------

To say you exist is a description, whereas
existence is not.

To use the word "existence" without a context is utter nonsense, even my six year old has that much sense. That you say you cannot understand such simple statements speaks volumes. Obviously you have a command of the enlgish language, your arguments and questions are nonsense.

Personally, I like to believe I exist and that my existence has meaning, that the universe outside of my perception is real, etc. but the validity and disposition of existence as it is commonly perceived are questionable according to modern physics. Nonetheless, questions remain and the origins of existence remain paradoxical.
 
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  • #26
Originally posted by wuliheron
We Can prove the disposition of water is to freeze below a certain temperature, we Can prove a lion's disposition is to hunt, etc. Thus far we have proven existence may not predate the big bang and may have end at some point in the distant future, but its disposition remains mysterious.

You managed to use three different meanings for the word disposition in as many instances. Such ambiguity certainly allows for many incorrect statements to be built that appear sensible.

Emperical evidence for a TOE would be nice. More than likely such evidence would have to be statistical in nature.

Are you ever going to specifically answer what you were referring to as "the validity of existence"?

To use the word "existence" without a context is utter nonsense

Any word needs context. What I am arguing here is that many apparent paradoxes come from stretching the use and applicability of words.

That you say you cannot understand such simple statements speaks volumes.

Instead of edging an ad hominem, why don't you take some time to clarify how your statement

Truth and falsehood are not the same thing as existence, that's why we have separate words for them

related to what I said:
In order to embed some meaning on the phrase

"Existence is false"

we need to twist the meaning and applicability of "false". The only sensible way to do it (that vaguely resembles the intent of the rest of your post) would be to interpret it as "existence can not be verified" or maybe "existence cannot be explained", which are not self-referential statements, and both can perfectly well be false without contradicting themselves.

Back to your most recent post...

Personally, I like to believe I exist and that my existence has meaning, that the universe outside of my perception is real, etc. but the validity and disposition of existence as it is commonly perceived are questionable according to modern physics.

Here, you seem to be actually referring to the validity of the common perception of existence, but you also keep talking about the validity of existence itself.

My main point with the last few posts has been that such language ambiguities can easily lead to "paradoxical" accounts of anything, and that this is not because "paradox" is interwoven in the fabric of reality, or any similarly grandiose-sounding statement, but because of ambiguous/inaccurate descriptions.
 
  • #27
Greetings !
Originally posted by wuliheron
There is no clear explanation for existence
Originally posted by ahrkron
Agreed, but that does not pose a paradox.
Nope, what does is the apparent inability
of providing a clear explanation according
to all reasoning capabilities we have so far.
So, it's not something that hasn't been
explained yet, it is something that so
far isn't supposed to have an explanation.
(Of course, we can't prove our current
reasoning capabilities will not change and
improve to accommodate existence in the future -
but because of the many faces that characterize
the PoE - the possibility of such new reasoning
is one of the most uncertain things ever.)
Originally posted by Mentat
According to Descartes' reasoning, it
seems that your doubt of your own existence
makes you just as one who doesn't exist
(or something like that). IOW, your existence
loses meaning when you start to doubt it.
But, that's not fair ! I'm not certain of
my existence like I am of math !
Oh... NO ! I'm turning into a shadow !
Oh... Yes ! This is the perfect cloacking
device - just tell people to doubt their
existence - I'm going to be a rich shadow !

Live long and prosper.
 
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  • #28
Originally posted by ahrkron
You managed to use three different meanings for the word disposition in as many instances. Such ambiguity certainly allows for many incorrect statements to be built that appear sensible.

Ambiguity is inherent in the situation. Modern science itself is ambiguous about existence. Currently there are eight widely respected distinct theories about existence. Some say everything is geometry, mind, information, etc. and which it might be is anyone's guess. To speak of existence in anything other than ambiguous terms is to express bias.

Are you ever going to specifically answer what you were referring to as "the validity of existence"?

Once I dreamed I was a butterfly, or am I really a butterfly dreaming I am a man?
Chuang Tzu

One of the more common suggestions for Quantum weirdness is that our universe is embedded inside or influenced by another we cannot perceive. Just as humanity once believed the Earth was flat, we may find that our perception of existence is entirely invalid or that existence presents a much more muddled a connundrum than we perceive.

Any word needs context. What I am arguing here is that many apparent paradoxes come from stretching the use and applicability of words.

It appears to me it is You who are stretching the meaning of words entirely out of context and merely making communication difficult. In particular, because you insist on imposing your own biased view of existence on any discussion of the concept. The idea that all paradoxes are merely semantic difficulties of language is nothing new, but logicians and other serious scholars disagree.

The Liar's Paradox is a case in point. After two thousand years of research it is considered anything but ambiguous. Of course, if a compulsive liar says, "Everything I say is a lie" the Liar's Paradox is given a context that makes rational sense if not logical sense. However, it is not so easy to give all of existence such a clarifying context.

quote:
--------------------------------------------------------------------------------
Personally, I like to believe I exist and that my existence has meaning, that the universe outside of my perception is real, etc. but the validity and disposition of existence as it is commonly perceived are questionable according to modern physics.
--------------------------------------------------------------------------------

Here, you seem to be actually referring to the validity of the common perception of existence, but you also keep talking about the validity of existence itself.

My main point with the last few posts has been that such language ambiguities can easily lead to "paradoxical" accounts of anything, and that this is not because "paradox" is interwoven in the fabric of reality, or any similarly grandiose-sounding statement, but because of ambiguous/inaccurate descriptions.

The idea of existence having any sort of "validity" entirely outside of the human context and perception is bizarre to say the least. Yet another indication of your unwillingness to contemplate the subject objectively.

Personally, I don't know if existence really is paradoxical or not... nor does it matter one wit to me. If modern science discovers we are all riding on the back of a giant turtle I will still live my life as I always have. You are free, of course, to hide your head in the sand instead and assert it is merely a semantic difficulty without so much as a shred of evidence to support such a position and, in fact, in direct defiance of the evidence.

Go ahead, prove there is no such thing as paradox. Prove the Liar's Paradox is just a result of ambiguity and vagueness. The fact is, you cannot and your arguments are just so much biased garbage. The word paradox and its definition remain in the dictionary because it is still useful whether you wish to acknowledge these simple facts or not.
 
  • #29
Originally posted by wuliheron
Of course, if a compulsive liar says, "Everything I say is a lie" the Liar's Paradox is given a context that makes rational sense if not logical sense.
I wasn't sure what the liar's paradox was, to be honest. But now you've mentioned it, I don't even see it as a paradox. Because if somebody always tells lies, then it would be impossible for that person to state "Everything I say is a lie" - simply because he would declaring a statement of truth, thus contradicting his own nature. So where's the paradox?
 
  • #30
Originally posted by Lifegazer
I wasn't sure what the liar's paradox was, to be honest. But now you've mentioned it, I don't even see it as a paradox. Because if somebody always tells lies, then it would be impossible for that person to state "Everything I say is a lie" - simply because he would declaring a statement of truth, thus contradicting his own nature. So where's the paradox?

Having a compulsion to lie does not mean it is impossible to tell the truth, just possibly more difficult than for the rest of us.
Irregardless, the paradox remains in that if they are not a compulsive liar they can most definitely make the statement. Then the paradox arises, if true then the statement is false, if false then the statement is true.
 
  • #31
This isn't an example of a paradox. It's like the guy who never speaks saying "I never speak.". It just means that the guy is being contrary to his own nature, because he obviously does speak. Similarly; the guy who says "I always tell lies." must speak the truth to make the statement. So he just contradicts his own nature. There is no paradox.
 
  • #32
So he just contradicts his own nature.
By definition that's what a paradox is.
 
  • #33
Originally posted by drag
But, that's not fair ! I'm not certain of
my existence like I am of math !
Oh... NO ! I'm turning into a shadow !
Oh... Yes ! This is the perfect cloacking
device - just tell people to doubt their
existence - I'm going to be a rich shadow !

Live long and prosper. [/B]

Very funny. I wasn't saying that you stop existing, by doubting it. I'm saying that anything you learn about your existence will be rather worthless (according to Descartes' reasoning), because you doubt your own existence (and your existence is required for you to take in knowledge). It's like saying that doubting the premise makes all other assertions, that are based on that premise, doubtful - and, according to Descartes, doubt makes any new knowledge worthless.
 
  • #34
Originally posted by Lifegazer
This isn't an example of a paradox. It's like the guy who never speaks saying "I never speak.". It just means that the guy is being contrary to his own nature, because he obviously does speak. Similarly; the guy who says "I always tell lies." must speak the truth to make the statement. So he just contradicts his own nature. There is no paradox.

Saying "I never speak" is just lying.

Let me try and explain the Liar's paradox another way. Let's take another statement, that is a derivative of the Liar's Paradox: This statement is false. You have two choices, either the statement is false, or it is true. However, if it is true, then the statement really is false (as that's what the statement is stating - "This statement is false"). And, if it is false, then the statement must be true (because that's what it states - "This statement is false"). Thus, in being true, it must be false; and in being false, it must be true. Thus, paradox - as it cannot be true or false, but most be both and neither.

Personally, I don't think that the Liar's Paradox really works exactly the same way. In fact, I think that it is a resolvable paradox. However, the one above ("This statement is false") is not resolvable.

I guess people relate the two, because by saying "everything I say is a lie", I am including that statement, and thus saying that that statement is false. But, I could be lying, when I say "everything I say is a lie", and thus it doesn't have to result in the "This statement is false" paradox.
 
  • #35
Originally posted by Mentat

... by saying "everything I say is a lie", I am including that statement, and thus saying that that statement is false. But, I could be lying, when I say "everything I say is a lie", and thus it doesn't have to result in the "This statement is false" paradox. [/B]

If you are lying about lying, then you are telling the truth which contradicts the fact that you were lying.
 

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