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Originally posted by Badwaterbut I believe they mean cause and effect.
Per your link, the first sentence:
"Logic is the study of the principles of valid demonstration and inference."
Sorry that Wiki went polysyllabic on you, but I believe they mean cause and effect. 😉
Within the context of the subject of this thread, what I said was accurate.
Why would you believe that when cause and effect have nothing inherently to do with "principles of valid demonstration and inference"? Your claim before that logic is nothing more than examination of cause and effect is simply wrong.
Here's a trivial example to see that you are way off-base. In everyday conversation, you probably make statements of causality of the form "if...then" where the antecedent and consequent are supposed to follow a certain temporal order. If logic was only in the business of cause and effect, then logical "if...then" statements should also characteristically be statements of causality, right? But that is just not the case. For example, the material conditional in logic (which can be stated within the form "if...then'😉 has nothing to do with causality. For instance, it doesn't require there to be a certain temporal relation between the antecedent and consequent. Rather, the material conditional is a truth-functional connective whose truth value just depends on the individual truth values of the antecedent and consequent. In first-order logic, the material conditional "If 1+1=2, then George W. Bush was the 43rd President of the United States of America" is true. You're telling us that this is a statement of cause and effect?
Originally posted by KellyJayso you tell me why a chair is a chair, pls?
I disagree, faith is how you define the variables in your logic! You can
setup your views upon anything by how you view the universe, as you
start to accept various and sundry views on what is true, will setup how
you view the universe around you. With that you put it all together and
come up with how you lay out how the universe should be colored or
looked at.
Kelly
and how do you know, in the room you presumably are in, that the ceiling is above you rather than otherwise?
faith is how we define words and their appropriate usage?
iOriginally posted by epiphinehaswait. we cannot observe in nature something that does not exist?
[b]How do you know that X and ~X can't be simultaneously true? Because it is illogical... the laws of logic were created by man to explain how things appeared to work in our universe.
First of all, the laws of logic (as opposed to the laws of physics) are not discovered by observing and analyzing the behavior of things around us. For exam ...[text shortened]... or not. Logical absolutes are conceptual realities that we discover rather than create.[/b]
logic depends on language -- on the meaning we agree is assigned to the use of words within a given context.
you use the word "observe" in a very narrow sense: to see or empirically confirm the presence of something.
How then do you establish that something does not exist? The Dodo, for example, is said to be extinct. How do we know that?
I believe the usage of the word "observe" also includes the observation of a thing's absence.
As in all things in our idea of reality, everything depends on consensus. We had reports that an Ivory Billed Woodpecker still survived in the Louisiana woodlands. Someone said they saw it. But no one since has been able to confirm that, despite many many attempts by literally too many birders to count -- you can't underestimate the enthusiasm of birders and they do migrate and flock together at the mere hint of sighting a bird thought to be extinct.
No confirmation? Well, then the poor bird is extinct all over again.
Pluto -- planet or not? so it goes on.
In fact, while some have said suicide is the only valid philosophical question, that is an unwarranted opinion. I was taught by a logician. He said at the outset to remember that philosophy came into existence to study the prime problem of human thought: the contradiction. Logic is the outgrowth of consideration of that problem, as well.
but logic really has only to do with validity, not truth.
We have to confirm or agree that our premises are true in order for the rules of logic to arrive at a valid conclusion that also is true, proved logically.
Start with a false premise and you still can construct a valid argument -- but it cannot be true.
Then, again, what is true? Often, only that on which we agree or can empirically confirm.
Originally posted by ScriabinIn fact, while some have said suicide is the only valid philosophical question, that is an unwarranted opinion.
wait. we cannot observe in nature something that does not exist?
logic depends on language -- on the meaning we agree is assigned to the use of words within a given context.
you use the word "observe" in a very narrow sense: to see or empirically confirm the presence of something.
How then do you establish that something does not exist? The Dodo, f ...[text shortened]... Then, again, what is true? Often, only that on which we agree or can empirically confirm.
There you go, picking on Camus again! 😉 But, I promised you I would read Frankl before arguing over Camus—and so I just now ransacked my bookshelves until I found Man’s Search for Meaning. I am not convinced that setting Frankl contra Camus doesn’t entail a misreading of Camus—but I am just going on some Frankl quotations that you offered here some time back.
You also once suggested a discussion/debate on “Frankl versus Camus”. I’ll get a bit up to speed and start a thread—likely within the week. LemonJello is a fellow Camusian of sorts, so maybe he’ll join in.
What say you?
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Originally posted by vistesdI disagree, Vistesd. That X&~X must be false is an axiom of first-order logic, but not of many non-classical logics. Traditionally, X & ~X must always be assigned a truth-value of 0, but what if X is a vague proposition? What if I said "I am fat" and "I am not fat"? It is conceivable that X & ~X could then have some non-zero truth-value. I could be a borderline case, neither average-weight nor obese. Consequently, X and ~X may have some 'fuzzy' truth-value and the conjunction of X and its negation may not be a true contradiction. There are also other non-classical logics.
The good Dr. S. defined an axiom as a standard of truth within a given domain of discourse.
Now, I’m just a schlock at this stuff. I’m a layperson who tries to reason well, and looks to the rules of logic in order to do so.
It seems to me that the rules of logic (such as ~(X & ~X)) provide standards of coherency. For another example, if one s ...[text shortened]... a private language, contra Wittgenstein, is possible).
Glad you’re here, by the way, CL. 🙂
My point is that logic should not be seen as a set of axioms from which we can check the validity of any inference. As it is now, logical axioms are merely syntactic axioms -- they are axioms which define (but not determine) the validity of an inference. Some logics may approach this question of validity differently. A modal logic will look very different to a fuzzy logic system and each of these will have different applications according to their context or language. My thought then is that logical axioms are human constructs -- though this is not to say that they are arbitrary.
Originally posted by Conrau KIn your examples the 'not' has a different meaning. In the original statement X & ~X, the ~ is defined specifically such that X & ~X can never be true.
I disagree, Vistesd. That X&~X must be false is an axiom of first-order logic, but not of many non-classical logics. Traditionally, X & ~X must always be assigned a truth-value of 0, but what if X is a vague proposition? What if I said "I am fat" and "I am not fat"? It is conceivable that X & ~X could then have some non-zero truth-value. I could be a border ...[text shortened]... its negation may not be a true contradiction. There are also other non-classical logics.
I would agree with vistesd that it is a question of coherency. A definition is never false. If it is then you are incoherent. If you put a set of definitions together and they contradict each other then you are incoherent.
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Originally posted by twhiteheadI think that you will find a very significant scholarly discussion on this very subject:
In your examples the 'not' has a different meaning. In the original statement X & ~X, the ~ is defined specifically such that X & ~X can never be true.
I would agree with vistesd that it is a question of coherency. A definition is never false. If it is then you are incoherent. If you put a set of definitions together and they contradict each other then you are incoherent.
http://plato.stanford.edu/entries/logic-fuzzy/
I think that your definition of negation does not correspond, at all, to our natural usage. I can recognise something is definitely blue; I can recognise something as definitionately not blue (for example, bold red). But in a spectrum from red to blue, there is an intermediary overlap in which the cut-off point between red and blue is unclear. I cannot say where the blue ends nor where the red begins because the meaning of red and blue are vague. I know which side is definitely is red and which is definitely blue, but I cannot clearly distinguish when these regions end. It seems natural then to assign it some fuzzy truth-value to that borderline region or perhaps to admit a truth-gap (in which case X&~X can neither be false or true.) A detailed summary can also be found at
http://plato.stanford.edu/entries/sorites-paradox/
A definition is never false.
?
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Originally posted by ChronicLeakyThis is also my view (but I might go further). Remember our formalism/realism thread? (adam, what are you waiting for?) My views there roughly translate to this debate.
Well, X and ~X are statements in a language.
Formal logic is simply a form of symbolic representation. We use it to provide a structure to communication and thought (the coherency, that vistesd mentions although I prefer the word consistency) but it's otherwise as much of a self-contained system as mathematics.
X and ~X can never be simultaneously true within the rules of the game, but without a game (i.e the language) then X and ~X are meaningless gibberish.
Edit - Obviously, this means that I think formal logic is a human construct.
Originally posted by Conrau KI don't see where your X & ~X fits in. Clearly all intermediate shades are ~Pure Blue and ~Pure red. Not one of them is both Red and ~Red or Blue and ~ Blue. I certainly don't see who one can assign some sort of fuzzy truth to them.
I think that your definition of negation does not correspond, at all, to our natural usage. I can recognise something is definitely blue; I can recognise something as definitionately not blue (for example, bold red). But in a spectrum from red to blue, there is an intermediary overlap in which the cut-off point between red and blue is unclear. I cannot say ...[text shortened]... rline region or perhaps to admit a truth-gap (in which case X&~X can neither be false or true.)
A definition is never false.
A definition is either simply an explanation of the words you are using or it is an axiom ie assumed to be true. It simply cannot be false. If you have two axioms that contradict each other then you are being incoherent.
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Originally posted by marieclaireSuppose I believe that logic is both (a) a matter of faith and (b) NOT a matter of faith, where "a matter of faith" has exactly the same meaning in both (a) and (b).
Hi all, I've been having a debate with a religious cousin who claims that logic is based on faith because the fundamental Laws of Logic cannot be proved (and therefore are accepted by faith).
I think that the fundamental Laws of Logic are man-made laws which explain our observations (ie: everything I observe conforms to these Laws of Logic, therefore ...[text shortened]... t this or point me where to read more about it? Google has not been terribly helpful!
Thanks
Now, if you believe that logic is a matter of faith--so that you can disbelieve such articles of faith like the law of non-contradiction--then you should be open to agreeing with me.
But if you agree with me, then you not only believe that logic is matter of faith, but you also believe and disbelieve this at the same time.
Fair enough. But what, then, are you *asserting*?
Originally posted by vistesdI am not setting Camus up vs. Frankl in such stark terms. It would be more precise to say that in the case of Albert Camus speaking in the Myth of Sisyphus vs. Viktor Frankl speaking in Man's Search for Meaning, I hold for Frankl as the better authority.
[b]In fact, while some have said suicide is the only valid philosophical question, that is an unwarranted opinion.
There you go, picking on Camus again! 😉 But, I promised you I would read Frankl before arguing over Camus—and so I just now ransacked my bookshelves until I found Man’s Search for Meaning. I am not convinced that setting Frankl ...[text shortened]... in the week. LemonJello is a fellow Camusian of sorts, so maybe he’ll join in.
What say you?[/b]
Camus didn't end up where he started in the above-captioned essay, so it would be unfair of me to set all of his work vs. Frankl. Furthermore, I am not really convinced by Frankl later work in Man's Search for Ultimate Meaning. He still seems to expect of me a rather large leap of faith -- to believe something about reality of which I am not now aware.
Ah, I may have stumbled on something useful. Try this on for size:
I choose not to accept as true or established fact that of which I cannot become aware, either through my own perceptions, or through those recounted by others whom I can accept as rational and reliable sources.
Folks can choose to believe whatever they like -- but discussions between those of us who adhere to a rational view and those who adhere to a faith-based, empirically or mathematically unconfirmable view, are meaningless.
Originally posted by PawnokeyholeMy cousin would argue that while he has the option of agreeing with you, he will decline that option and instead believe the law of non-contradiction to be true.
Suppose I believe that logic is both (a) a matter of faith and (b) NOT a matter of faith, where "a matter of faith" has exactly the same meaning in both (a) and (b).
Now, if you believe that logic is a matter of faith--so that you can disbelieve such articles of faith like the law of non-contradiction--then you should be open to agreeing with me.
...[text shortened]... eve and disbelieve this at the same time.
Fair enough. But what, then, are you *asserting*?
But yes, he could theoretically believe and disbelieve at the same time as, although this is illogical, faith doesn't have to follow the laws of logic.
Originally posted by ScriabinThen the cobra behind that tree lurking for that Indian is not real because the poor man is not aware of its existence;
I am not setting Camus up vs. Frankl in such stark terms. It would be more precise to say that in the case of Albert Camus speaking in the Myth of Sisyphus vs. Viktor Frankl speaking in Man's Search for Meaning, I hold for Frankl as the better authority.
Camus didn't end up where he started in the above-captioned essay, so it would be unfair of me to set ...[text shortened]... o adhere to a faith-based, empirically or mathematically unconfirmable view, are meaningless.
and that mighty 1950RHP who is cut in pieces after 30 moves from a 2360RHP but he cannot understand the reason why and complains that his opponent is an engine user, he must be definately right;
and, since my emotions and my thoughts and my philosophy cannot be depicted and/ or described by means of a mathematic formula, my feelings when I mourn for the loss of somebody I love are not true;
It seems to me that being genuine is enough; I think that, believing whatever your intelligence accepts and rejecting whatever seeks to destroy your intelligence is OK; thus, I believe that accepting in full the responsibility of your actions and being constantly in awareness is as effficient as it gets😵