Does logic equal truth?

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  • #1
newton1
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i think logic is the logic for the limit of human intelligence
like long time ago
all people believe what aristotle said is very logic
because that time it is the limit of human intelligence
but now human is more clever than before
so people now think aristotle is no logic
what you think about logic??
 

Answers and Replies

  • #2
Ivan Seeking
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We surely have more information which helps a lot.

Many Greeks thought that all of reality could be deduced by pure logic. This approach obviously leads to errors. Also, one could argue that we are truly smarter now than then because of the world in which we live. The problem comes with how we define smart.

Personally, the first time I read Socrates, and perhaps still, I was sure I had never encountered a smarter or cleverer individual. We just have to filter for the information disparity between our perspective and his.
 
  • #3
surely logic isn't dependant on intelligence? you say 'that's logical' not 'that's complicated and intelligently deduced using advanced theorems and knowledge of all that has come before'. logic is like 'gods are immortal, all men are mortal therefore no man is a god', that sort of thinking is even atributed to socrates, if something was 'logical' 2000 years ago it will remain so forever, the only thing that changes is what we use this logic to prove and with what axioms. if things were said back then that are now considered false then it is because the axioms were incorrect.
 
  • #4
newton1
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Originally posted by steppenwolf
surely logic isn't dependant on intelligence? you say 'that's logical' not 'that's complicated and intelligently deduced using advanced theorems and knowledge of all that has come before'. logic is like 'gods are immortal, all men are mortal therefore no man is a god', that sort of thinking is even atributed to socrates, if something was 'logical' 2000 years ago it will remain so forever, the only thing that changes is what we use this logic to prove and with what axioms. if things were said back then that are now considered false then it is because the axioms were incorrect.

maybe logic is come from this ideal
but the problem is even at now we can't say what we learning is truth
you said logic is immortal
but theory of human create is not perfect
so what u mean is no man is logic??
 
  • #5
kyle_soule
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In 1850 it was logical to assume the Earth was flat. This is undoubtedly incorrect. Logic today tells us the Earth is round. It was logical then to assume the opposite of our logic today. This tells us that logic is not universally or forever true, whereas, truth is universal and forever, so one would see that logic does not equal truth, nor would truth necessarily equal logic. More often than not truth is logical, but logical is not truth.

EDIT: It seems that there are two kinds of logic, one based primarily on ignorance, or relative logic, and one based on universal laws/truths, or true logic, the former is much like a theory. You cannot distinuish between the two unless you either a) have all the facts or b) have an infinite amount of time to test them.
 
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  • #6
totoro
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Originally posted by Newton1
maybe logic is come from this ideal
but the problem is even at now we can't say what we learning is truth
you said logic is immortal
but theory of human create is not perfect
so what u mean is no man is logic??


i agree with that no man is perfect. but i believe there is no limit to human thinking. i have been thinking that if we want to proceed to higher level, we should go beyond logic and rational thinking. IMO.

but ofcourse we should go through logical and rational thinking before we can go beyond. if you ask me what is beyond that... i still in the middle of searching.



what you think about logic??


i think that logic is what we all use everyday for living. it just like common sense. we use logical thinking to explained everything that happen.
 
  • #7
Kerrie
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logic is truly subjective because it comes from the human mind...that doesn't mean that it is truthful or untruthful, but it depends entirely on the circumstances surrounding the claimed logic...
 
  • #8
wuliheron
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Logic is the science of the absurd.

As Kurt Godel demonstrated, any system requires certain axioms we must simply take on faith. In the case of logic, it is a faith in the absurd. In fact, all the various kinds of logistics that have been developed over the eons are ultimately based on reductio ad absurdum, a systematic way of demonstrating that alternative ways of thinking are at least as absurd as the logic we are using.

Because of this logic can be seen as a systematic means of organizing absurdities into heirarchies. A tautological way of thinking which only has meaning within the context of human perception and specific applications. Before the discovery that the world is round, for example, to think the world was round was considered absurd and illogical. Before Galileo demonstrated the weak equivalency principle, it was considered absurd and illogical to believe objects of different weights could fall to Earth at the same rate.

Thus, to say logic is the limit of human perception is to deny the absurd foundations of logic. To deny our own irrational feelings among other things. :0)
 
  • #9
Les Sleeth
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Logic is not open to subjective interpretation, but rather is as close to mathematical reasoning as one can get. In intelligence, and that is reason, there are really two parts: logic and premises. As Ivan said, it used to be believed that one could arrive at truth by logic alone, and this rationalistic view dominated philosophy until the 19th century when empiricism really took off.

Then it was clearly recognized that the information one reasons with must be accurate for logic to lead one to accurate conclusions. Thus experience was solidly incorporated into the reasoning process. Premises began to require the experience of observation to validate them. That combined with the systematizing of logic with works like Boole’s Mathematical Analysis of Logic resulted in great discoveries in logic that came to be used by linguists, scientists, philosophers, mathematicians, electronic engineers and even music composers and psychologists.

There still remains some question about what sorts of experience should be permitted to establish premises. People have argued that intuition and inner experience have relevance, others say only sense experience is to be allowed. But I have to disagree with Wuli that the foundations of logic are absurd. The methods of logic are virtually undisputed and function flawlessly when applied correctly . . . it is the reason of order, and it is used to help understand that which has order. What may be absurd is when people assume order (and therefore logic) is all there is to existence; but that would be due to the absurdity of the premise, and not a fault of logic.
 
  • #10
Mentat
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Originally posted by Kerrie
logic is truly subjective because it comes from the human mind...that doesn't mean that it is truthful or untruthful, but it depends entirely on the circumstances surrounding the claimed logic...

Logic is also subjective because there are different reasoning systems that can be used within the realm of "logic". One could make an utterly preposterous conclusion, from sound/reasonable premises - but the fact that s/he is using premises to build toward a conclusion means that s/he is using logic.
 
  • #11
Les Sleeth
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Originally posted by Mentat
Logic is also subjective because there are different reasoning systems that can be used within the realm of "logic". One could make an utterly preposterous conclusion, from sound/reasonable premises - but the fact that s/he is using premises to build toward a conclusion means that s/he is using logic.

If you want to say that people make up their own rules, and ignore the extremely well-established discipline of logic, then I suppose you can say it can be subjective . . . but that's not really logic either.

If people obey the formal rules of logic, and reason with a correct and complete set of premises, then the conclusion will be correct every time. When an incorrect conclusion is found to have resulted from correct logic, it is always because of discovering something was missing from the premises. So proper logic is not subjective.
 
  • #12
wuliheron
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Originally posted by LW Sleeth

But I have to disagree with Wuli that the foundations of logic are absurd. The methods of logic are virtually undisputed and function flawlessly when applied correctly . . . it is the reason of order, and it is used to help understand that which has order. What may be absurd is when people assume order (and therefore logic) is all there is to existence; but that would be due to the absurdity of the premise, and not a fault of logic. [/B]

Without the concept of the absurd to provide context, logic has no meaning. Without the illogical, the logical has no meaning. Hence you contradict yourself when you say, "what may be absurd is when people assume order is all there is to existence."

The highly structured language of logic is built upon a foundation of natural language which is repleate with vague terms such as "absurd". Chaos and order, vague and explicite, define each other and, as history has repeatedly demonstrated, what we have believed to be explicitely ordered has turned out to be random and vague and vice versa. It may be expedient and practical in many respects to assume some things are ultimately ordered, but in the final analysis the map is not the territory by the very definition of logic. To assert otherwise is to invoke absurdity.
 
  • #13
newton1
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so
u all think logic is not equal to truth...right??
 
  • #14
Mentat
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Originally posted by LW Sleeth
If you want to say that people make up their own rules, and ignore the extremely well-established discipline of logic, then I suppose you can say it can be subjective . . . but that's not really logic either.

If people obey the formal rules of logic, and reason with a correct and complete set of premises, then the conclusion will be correct every time. When an incorrect conclusion is found to have resulted from correct logic, it is always because of discovering something was missing from the premises. So proper logic is not subjective.

This is incorrect. If I make the premises:

1) Everything we know about reality is known through our senses.

2) We can never experience anything, outside of our own conscious awareness.

And then conclude that reality must come from within. I have come to Lifegazer's Mind hypothesis with perfectly reasonable/true premises. That doesn't mean that lifegazer is necessarily right, does it?
 
  • #15
Les Sleeth
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Originally posted by wuliheron
Without the concept of the absurd to provide context, logic has no meaning. Without the illogical, the logical has no meaning. Hence you contradict yourself when you say. . . Chaos and order, vague and explicite, define each other . . .

I suspect your views on paradox make you want to create one in every setting. It may be that being able to recognize illogic is a skill one needs to effectively apply logic, but I don't believe it has much to do with providing the context. Order exists, and we had nothing to do with that. It is here, and it overwhelmingly influences our existence. The rules that link order can be represented in the mind, and the mental linkage between order principles is logic. If everyone were always perfectly logical, then there would be no need to know about illogic. Therefore, logic can stand on its own because it reflects a certain way reality actually works.

Does reality operate chaotically too? Yes, but logic isn't about that. Logic is about what it's about, and in that respect it seems to work perfectly.

Originally posted by wuliheron
. . . as history has repeatedly demonstrated, what we have believed to be explicitely ordered has turned out to be random and vague and vice versa. It may be expedient and practical in many respects to assume some things are ultimately ordered, but in the final analysis the map is not the territory by the very definition of logic. To assert otherwise is to invoke absurdity

What "we have believed" to be ordered has nothing to do with logic. If it really is ordered, then logic can be used with it. Whether or not things are ultimately ordered also is irrelevant. All that matters is that some aspects of reality are ordered, and logic is the mental tool we have for understanding it. Because order has principles, so too does logic. They are not absurd, and they are not subjective (except in the sense they are applied inside one's brain); logic principles simply mirror something that goes on in reality. And it is pointless to object they can't work perfectly on everything. They aren't meant for everthing.
 
  • #16
wuliheron
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Originally posted by Newton1
so
u all think logic is not equal to truth...right??

There are multiple kinds of logic just as there are multiple kinds of mathematics. Some mathematics say 1+1=5. No, logic is not equal to truth, at least, not outside of a given context. At best logic is a pragmatic pratice and at worste a form of fundamentalism which can lead to all sorts of destructive behavior.
 
  • #17
newton1
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Originally posted by totoro
i agree with that no man is perfect. but i believe there is no limit to human thinking. i have been thinking that if we want to proceed to higher level, we should go beyond logic and rational thinking. IMO.

but ofcourse we should go through logical and rational thinking before we can go beyond. if you ask me what is beyond that... i still in the middle of searching.


i am not discuss is that humam are intelligence at here
i haven't say that human brain is not powerful
i just reply to steppenwolf with his view only





i think that logic is what we all use everyday for living. it just like common sense. we use logical thinking to explained everything that happen.
 
  • #18
Moetasim
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logic = truth: when logic is logical.
 
  • #19
Les Sleeth
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Originally posted by Mentat
This is incorrect. If I make the premises:

1) Everything we know about reality is known through our senses.

2) We can never experience anything, outside of our own conscious awareness.

And then conclude that reality must come from within. I have come to Lifegazer's Mind hypothesis with perfectly reasonable/true premises. That doesn't mean that lifegazer is necessarily right, does it?

Yes, but are his premises correct? (Plus, even if they are I don't see how his conclusion follows.) See, if you want to take philosophy back to the dark ages, then you can assert anything as a premise and then go on a reasoning lark. But today we accept the principle of the empirical method for establishing a premise, and that is it must be verified by experience.

How do you verify "We can never experience anything, outside of our own conscious awareness"? It is true we can only experience our own consciousness, but all appearances tell us we are being fed information from outside ourselves. How can LG prove his premise experientially? And it is one thing to say we can only know reality within, and another to say all of reality itself is within. It doesn't distinguish between the knower and what is known. Again, that contradicts our experience.
 
  • #20
newton1
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Originally posted by Moetasim
logic = truth: when logic is logical.

well
how you defined which logic is logical??
 
  • #21
Les Sleeth
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Originally posted by Newton1
so
u all think logic is not equal to truth...right??

What I believe is that logic plus correct premises (you cannot leave either out of the equation) leads to insights about the nature of ordered things.

But if you mean truth and logic are the same thing, then no because there are things which do not lend themselves to order (such as love) but which nonetheless exist and so are "truth." It isn't by logic that one knows and understands love, but through another avenue.
 
  • #22
Mentat
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Originally posted by Newton1
well
how you defined which logic is logical??

It's obvious that all logic is logical. That's like trying to figure out which aliens are alien to us.
 
  • #23
Moetasim
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This is a difficult question. But I think truth is always truth and need not the help of logic. Logic is only needed when there is some doubt. So if someone satisfies others with his logic or reasoning then its said to be logical and if he is not able to do so then ...I think I must reply it sometime later in a better way!
 
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  • #24
Les Sleeth
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Originally posted by Newton1
well
how you defined which logic is logical??

I wonder if you know how well established the discipline of logic is (you can study it in any decent university in the world). It is quite mathematical, and not open to casual manipulations.

In the sense that logic is reasoning math, when you put good information into proper logic formulas, you get good results. If you use incorrect or incomplete info (i.e., premises), and/or your formula is wrong, or if you try to apply logic to something it won't work with, then you will not get good results.
 
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  • #25
newton1
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If people obey the formal rules of logic, and reason with a correct and complete set of premises, then the conclusion will be correct every time. When an incorrect conclusion is found to have resulted from correct logic, it is always because of discovering something was missing from the premises. So proper logic is not subjective. [/B][/QUOTE]


yes...my opinion is logic is the way to pursue the truth
but logic is not equal to truth
because starting of logic maybe is wrong
like i say in my 1st post
logic is the limit of the human ability at that moment
 
  • #26
newton1
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Originally posted by LW Sleeth
I wonder if you know just how well established the discipline of logic is. You could fill a library with books on it, and study it in any decent university in the world. It is very mathematical, and not open to casual manipulations. If you haven't read Tom's thread on it, that would be a good place to get the basics.

In the sense that logic is reasoning math, when you put good information into proper logic formulas, you get good results. If you use incorrect or incomplete info (i.e., premises), and/or your formula is wrong, or if you try to apply logic to something it won't work with, then you will not get good results.

i think you get the wrong ideal what i say
did u read about the history of mathematics??
when human start develop the maths
they go many wrong way
but it's also a logic at that time
 
  • #27
wuliheron
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Originally posted by Moetasim
logic = truth: when logic is logical.

The problem with this statement is that we can begin with false premises, yet reach a true conclusion nonetheless. Logic is a wonderful tool, but sometimes I use a wrench to hammer things, etc. and it works just fine. It can also save a lot of time and inspire a great deal of creativity.
 
  • #28
newton1
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the whole ideal of devalop the science is trial and error
even logic of mathematic also like that
 
  • #29
Les Sleeth
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Originally posted by Newton1
i think you get the wrong ideal what i say
did u read about the history of mathematics??
when human start develop the maths
they go many wrong way
but it's also a logic at that time

It is true that the rules of logic have gone through the discovery process . . . but I thought you were talking about the "ideal" of logic, not misunderstandings we've had (and have).

What has really sent logic ahead leaps and bounds is empiricism because there you actually work with what is ordered. You better get it right or you will fail to produce. That failure won't just be in your head, but it will be out there for everyone to see. But then, so are the successes.

That is why this philosophy section of PF is stronger, in my opinion, than one you might find at a purely philosophical forum. It's because people here are more determined to reconcile facts and observations with their philosophies, and not just string a bunch of ideas together which may be logical, but have little relevance to observed reality.
 
  • #30
newton1
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Originally posted by LW Sleeth
It is true that the rules of logic have gone through the discovery process . . . but I thought you were talking about the "ideal" of logic, not misunderstandings we've had (and have).

What has really sent logic ahead leaps and bounds is empiricism because there you actually work with what is ordered. You better get it right or you will fail to produce. That failure won't just be in your head, but it will be out there for everyone to see. But then, so are the successes.

That is why this philosophy section of PF is stronger, in my opinion, than one you might find at a purely philosophical forum. It's because people here are more determined to reconcile facts and observations with their philosophies, and not just string a bunch of ideas together which may be logical, but have little relevance to observed reality.

i know this is the way of logic
i think u should learn how to put your subjective and pride away when discuss
something at here
 
  • #31
Les Sleeth
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Originally posted by Newton1
i know this is the way of logic
i think u should learn how to put your subjective and pride away when discuss
something at here

I am sorry Will if I've seemed some way that's disturbing to you. No insult intended. I have just been attempting to take the ambiguity out of the way you've been presenting logic. My only point has been to insist there is no ambiguity about logic as a discipline. Outside the discipline . . . well, the world is a crazy place.
 
  • #32
newton1
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Originally posted by LW Sleeth
I am sorry Will if I've seemed some way that's disturbing to you. No insult intended. I have just been attempting to take the ambiguity out of the way you've been presenting logic. My only point has been to insist there is no ambiguity about logic as a discipline. Outside the discipline . . . well, the world is a crazy place.


i am sorry too because my misunderstanding
anyway
thank you your suggestion
and go on
if you have more idea about logic
 
  • #33
newton1
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i get the answer from a professor
he say logic is a skill we prove something or find a conculsion
the process of logic will not be wrong
the problem is starting condition we assume must be right
to decide the conculsion is truth or wrong is depend on what we assume at 1st
and not depend on the logic
 
  • #34
Ivan Seeking
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Originally posted by Newton1
i get the answer from a professor
he say logic is a skill we prove something or find a conculsion
the process of logic will not be wrong
the problem is starting condition we assume must be right
to decide the conculsion is truth or wrong is depend on what we assume at 1st and not depend on the logic

This assumes that we think logically. Within our process of logic are assumptions. I think that Gödel’s Incompleteness theorem is the mathematical equivalent of this statement
 
  • #35
Mentat
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Originally posted by LW Sleeth
Yes, but are his premises correct? (Plus, even if they are I don't see how his conclusion follows.) See, if you want to take philosophy back to the dark ages, then you can assert anything as a premise and then go on a reasoning lark. But today we accept the principle of the empirical method for establishing a premise, and that is it must be verified by experience.

How do you verify "We can never experience anything, outside of our own conscious awareness"? It is true we can only experience our own consciousness, but all appearances tell us we are being fed information from outside ourselves. How can LG prove his premise experientially? And it is one thing to say we can only know reality within, and another to say all of reality itself is within. It doesn't distinguish between the knower and what is known. Again, that contradicts our experience.

LW Sleeth, you cannot disprove the Mind hypothesis, by talking about empirical testing. What's the use of empirical testing in a universe where the Mind produces all of our reality, and thus everything that we see will just be a "Mind-ful" projection?

Besides, it was just the only example I could think of at the time. Other members have come up with much better examples, in other threads. I'm just making the point that logic can be used to prove things that the same logic, but with different reasoning systems can disprove. IOW, logic is always the same, but the reasoning systems used can be differen, even contradictory, and thus none of them can be "right" or "true".
 

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