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Contradiction, Statements, and System.

 
  

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—| x |—
09:15 / 09.07.03
Over in another thread, I remark:

We know that from contradiction we can get anything (any statement is derivable from a contradiction).

and Quantum says:

This fascinates me, would you start a thread on it?

So here’s the damn thread!

I don’t really know how much there is to say about this, but it might spark some interesting discussions. It is certainly fascinating to me: ever since I discover this “rule” in my Logic I class it has provided one of the cornerstones and guides to my work of the last five years.

It’s quite simple, really. When we are dealing with a system of inference that relies on the rules of logic, then, if we have a contradiction present in our derivation, then we can logically derive any statement we want. I looked for some reference material on this, but my main logic text is out on loan, so in the back up text, A Modern Formal Logic Primer, by Paul Teller, we find, “…from a contradiction you can prove anything…Suppose that in a derivation you have already derived X and ~X [NB: in logical notation ‘~’ is used to stand in for the one place connective not]. Let Y be any sentence you like you can then derive Y” (96).

In a formal derivation this is simply a rule that we can follow:

.
.
.
n………........X…..Premise
n + m…......~X…..Premise
n + m + 1…~Y…..Assumption.
n + m + 2…..X…..Repeat n.
n + m + 3…~X…..Repeat n + m.
n + m + 4…..Y…..Reductio n + m +1—n + m + 3.

I hope that is more or less clear to people, even if they have no clue what a derivation is in formal logic! This is also called, more basically, negation elimination (or negation introduction, we could have assumed Y and ended up with ~Y). To put this a little more simply, if we have a contradiction within our system, then we can introduce any statement we’d like into that system, and from the contradiction (and by assuming our desired statement’s contrary) we prove that statement. Of course, most would say that’s not much of a proof, but if we begin with contradiction as the generator, then…
 
 
Quantum
10:38 / 09.07.03
A contradiction is surely an indication that there's a mistake somewhere, either in the working or the premises. If your proof contains a contradiction like X and ~X, then it's invalid. As evidenced by being able to prove any statement from it.

"if we have a contradiction present in our derivation, then we can logically derive any statement we want"
So a good reason to avoid contradictions, they make a nonsense of one's proof.
 
 
wiracocha
12:54 / 09.07.03
'Do I contradict myself? very well I contradict myself
(I am large, I contain multitudes).'

I remember this quote from somewhere, no idea who it was sorry! I have always been interested in this idea of things being most apparent in their antethesis. Is it a case of mere Orwellian double think or something else?

We always seem to act contrary to that which we would think we uphold in our minds. For instance we may be aware of and against the evils of big business like cocoa cola, but then we go back to work the next day and perpetuate its existance. How far then is it possible to remain true to 'what one is'? In logic I think it is more our mythologising of what we think we are than actually contradicting what is our true nature. So it is more to do with our lack of understanding ourselves than actual false propositions existing in the world.

Also I think that our conceptions of certain issues are always our own idealised understanding of those issues and usually contary to, or independant of what another meant by it. But this inconsistancy is not always a bad thing as it still acts as a way of stimulating and diversifying discourse.

Sorry if ive gone off the topic a bit! but that is exactly what I mean when I say that a person only brings his/her own interests/issues to bear on a potentally contradictory subject! babbling and getting used to posting I suppose...
 
 
Spaniel
09:05 / 10.07.03
Quote? Walt Whitman.

One of my favs.
 
 
.
15:34 / 11.07.03
Anything follows a contradiction

With all respect to my punctuated Zero friend, I find the explanation you've given hard to follow, and I actually studied formal logic (albeit too many years ago now)...

I always thought that the claim "Anything follows from a contradiction" related to the slightly funky way in which the material implication symbol works in symbolic logic. For those not versed in symbolic logic, material implication (represented here by the -> symbol) is supposed to be translated as "If P is true then Q will be true".

So if we have a proposition that says:
P -> Q

The overall proposition will be true if P is true and Q is true. In other words, (if P then Q) is true if both P and Q are true. However, (if P then Q) is actually true in two other situations too: firstly when both P and Q are false, which makes a kind of sense; but also when P is false but Q is true. The full truth table for this is:

1) P = T, Q = T, (P -> Q) = T. In other words, if P is true, and Q is true, then it is true that (P then Q).

2) P = T, Q = F, (P -> Q) = F. In other words, if P is true, and Q is false, then it is not true that (P then Q). Importantly, this is the only case where (P -> Q) is false.

3) P = F, Q = T, (P -> Q) = T. In other words, if P is false, but Q is true, then it is still true that (P then Q). This is the really funky bit.

4) P = F, Q = F, (P -> Q) = T. In other words, if P is false, and Q is false, then it is true that (P then Q).

So it's 3) and 4) above where things go odd. The workings of -> mean that the over propositions (P -> Q) is only false if P is true but Q isn't.

So this taken, if we stick a contradiction into this kind of proposition, you can get:

(~P & P) -> Q

Now, the conjunction of (~P & P) is false, because the & is only considered to be true when both sides are true, which cannot be the case with P and ~P, regardless of P's original truth value. But as we have seen above, the only case where the -> is false would be if (~P & P) were somehow true but Q false. Hence in the above example, no matter what value Q has, the overall proposition is true, and Q can indeed be true within that. Which means that despite containing a contradiction, the complete proposition is true...

...well in symbolic logic at least.

So is this a similar to ...>0<...'s original thing? I must admit now that my logic is totally rusty, so please point out any errors.

If anything, looking back on this style of logic now after many years out of uni, it strikes me exactly how contrived it seems. Damn the excluded middle!
 
 
—| x |—
21:08 / 19.07.03
With all respect to my punctuated Zero friend, I find the explanation you've given hard to follow…

Sorry ‘bout that. I tried to keep it simple—what were your particular difficulties?

I always thought that the claim ‘Anything follows from a contradiction’ related to the slightly funky way in which the material implication symbol works in symbolic logic. For those not versed in symbolic logic, material implication (represented here by the -> symbol) is supposed to be translated as "If P is true then Q will be true".

Hmm, not that I am aware of, but it might: I’ll check out your work below!

So if we have a proposition that says:

P -> Q

The overall proposition will be true if P is true and Q is true. In other words, (if P then Q) is true if both P and Q are true. However, (if P then Q) is actually true in two other situations too: firstly when both P and Q are false, which makes a kind of sense; but also when P is false but Q is true.


Yes, this is correct. A conditional claim (“material implication”) is only false when P is true, but Q is false (As you note in your expansion of a truth-table—nice job, btw: I typically confuse 2 & 3 on a regular basis, which means I typically have to take a moment or two to think about how it works—usually making up some sort of example to remember. Perhaps, say, “If you are a mother, then you are female.” From this I can go “Yeah, it can be false that x is a mother, but true that x is female, but it can’t be true that x is a mother & false that x is female.).

So this taken, if we stick a contradiction into this kind of proposition, you can get:

(~P & P) -> Q

Now, the conjunction of (~P & P) is false, because the & is only considered to be true when both sides are true, which cannot be the case with P and ~P, regardless of P's original truth value. But as we have seen above, the only case where the -> is false would be if (~P & P) were somehow true but Q false. Hence in the above example, no matter what value Q has, the overall proposition is true, and Q can indeed be true within that. Which means that despite containing a contradiction, the complete proposition is true...


OK, I see what you are saying now, and it makes sense to me. However, within the context of the derivation, we’d either have to have that conditional ((~P & P)-->Q) & the conjunction P & ~ P in order to introduce derive Q, or we would have to construct the conditional &/v the conjunction. So yes, you are entirely correct that “material implication” is involved—it seems to me to prove how to get “any statement we want from a contradiction” validly within the rules of a traditional symbolic logic. But, as far as I am aware, the rule is as I’ve stated it. It might be like a “short hand” in a way similar to how we are allowed to claim, if we have the rule, “modus tollens” a go straight from having ~Q along with P-->Q, to having ~P in our derivation.

So is this a similar to ...>0<...'s original thing? I must admit now that my logic is totally rusty, so please point out any errors.

No errors, seems to prove how deriving a statement from a contradiction is a valid maneuver, and yes, is on track with what I was saying.

If anything, looking back on this style of logic now after many years out of uni, it strikes me exactly how contrived it seems. Damn the excluded middle!

Well, yes, but it is intended to be the abstract representation of the structure of our rational thought. Under this sort of premise it brings out the subtle “contrived”—or better, “constructed”—nature of all so-called “rational thought.” Put differently, on close and sincere examination what human endeavour doesn’t seem contrived?

Note also that bivalent classical logics are not the only sorts of logics out there. There is a branch of logic that is called “para-consistent.” These logicians allow contradictions into their system, but have rules governing the extent and limits of such contradiction—it might be the case that under such logics we can’t get anything we want from a specific contradiction, but perhaps only a limited set of statements. I only know a little about this sort of logic, so please forgive the sketchy exposition.

Personally, I find the “Law of the Excluded Middle” very exciting, but that’s because I have written a few papers that feature its deconstruction &/v its use in deconstructing binary pairings wrt our phenomenal experience.
 
 
alas
13:50 / 24.07.03
"A foolish consistency is the hobgoblin of little minds, beloved by little statesmen, philosophers, and divines," quoth Emerson.

Hmmmm ... I'm not particularly well versed in symbolic logic. Ok, I'm not even versed in symbolic logic. But I can see it may have value in an academic sense, and I'm an academic, but I'm not sure I trust it: is my distrust a knee-jerk ignorance, a romantic fuzzy-headedness, or something that is worth paying attention to?

It seems to me that some of the deepest truths are paradoxical. Can symbolic logic deal with a paradox? (It's an honest question, from honest ignorance.)

yours, in symbolic illogic . . .
 
 
Lurid Archive
14:07 / 24.07.03
It seems to me that some of the deepest truths are paradoxical. Can symbolic logic deal with a paradox?

Kinda, but not particularly well. I think it is probably fair to say that symbolic logic ignores those truths that you'd call "deep". It is concerned with different stuff.

Also, it should be noted that people often use "paradoxical" to mean "counter intuitive", whereas in logic these sorts of terms are much stricter in meaning. A "contradiction" in logic isn't something merely unexpected. It is something more like:

"All citizens shall be guaranteed a fair trial"
&
"Citizens suspected of terrorism shall not be guaranteed a fair trial."

I know thats mostly clear, but the divergence of natural language and technical terms can cause confusion.
 
 
Tom Coates
11:08 / 25.07.03
I don't want to take this in a dreary tangent of moral relativism, but I think the main value in being able to hold contradictions in your mind while simultaneously being aware that they're contradictions is that you're able to deal with a lack of certainty. Let me put that in a better way - there is a continual desire to reach an absolute point of clarify and understanding of the world - this is sometimes negatively called simplistic determinism. The urge is a valuable one because it pushes us to refine our ideas and work towards better models. But having said that, there's also often a desire to assert certainty where certainly simply does not yet exist - perhaps never can exist.

The terrible danger is that we collapse reality down to an unrealistic and absolutist view in a desperate attempt to reconcile contradictions in our thought, rather than work with the sense that there are gaps that still need to be filled, thigns that still need investigating. Etc. etc.

So contradictions in themselves aren't necessarily good, but being able to keep them in your head rather than forcing a monist view on the world is crucial to intellectual work....
 
 
Lurid Archive
13:12 / 25.07.03
I kwow what you mean Tom, but I don't findh it entirely convincing. I think the alternatives you are outlining are incomplete at best, though they do seem to resonate with lots of people here. (One of the reasons I chose the example of such a questionable contradiction is that I sometimes get the impression that people think contradictions must always be positive.)

In short, uncertainty is something we all have to deal with, and I don't really see why one needs to embrace contradiction to deal with it. Though, as before, it does depend on what one means by "contradiction". For instance, I can believe that smoking is harmful and still smoke - this is not a contradiction, IMO, unless I believe that I must always do what is most healthy.
 
 
—| x |—
08:31 / 26.07.03
…I can see [symbolic logic] may have value in an academic sense, and I'm an academic, but I'm not sure I trust it: is my distrust a knee-jerk ignorance, a romantic fuzzy-headedness, or something that is worth paying attention to?

I don’t think there is a simple answer to this question, alas (your name fits so very, very nice in places, mon frere!). Not really knowing you v. well prevents a direct answer, but let me share some thoughts with you.

First, I think that every student everywhere should at least take a first year logic course. It is difficult and requires a high degree of dedication, but teaches rigour and clarity of thought. Personally, I felt that after taking my Logic I course my essay writing skills improved: it is like brain-lego for thought & theory construction. Thus, I feel quite strongly that it is important in an academic sense. I mean, I’ve read some people’s essays where the clarity of thought is v. murky &/v the connection between ideas, while present, doesn’t “flow” or readily present themselves. I feel that knowing a bit of SL teaches a person how to structure paragraphs much better—esp. in developing an argument: state the paragraph’s main point in the opening sentence, link the chain of evidence supporting claim in a clear, precise, and logical manner, conclude the paragraph by restating the now supported point. Begin the next paragraph hot on the heels of the point just argued for previously. I feel a bit of SL provides the skills to write tight, clear, and concise papers. Definitely a plus for today’s busy people: to the point and not superfluous.

Second, logic, to some, has a bad name. I feel that some people tend to look at logic and figure it is for the machines and computers—what’s logic doing in a humanities department?! I mean, for someone either not interested in logic or taking it because hir compsci degree requires it logic likely seems v. much like math did in school: when are we gonna’ use this? This perhaps might generate a “distrust” in logic for some. Here, I would say this is linked directly to the idea that humans are spontaneous and free and that notions of “logic”—in its cold and calculating ways—tie people down and chain them to “contrived” structures. Again, what human endeavour—no matter how profound—doesn’t tie its followers down to contrived notions?

Also related are historical movements—such as “Logical Positivism”—which were based on some sort of “logical” foundation (although, funnily enough perhaps, tenets of “Logical Positivism,” IIRC, are all stated in “natural” language!), and have also fallen into disrepute through their abysmal failures.

Third, I think there can certainly be a “romantic” side to logic; however, this isn’t going to come out in most people. I tend to think of some of the great logicians here and their passion not only for logic as a study, but for life in general. I also tend to think of some of the people in history who made significant contributions to our growth who were, if not learned in formal logics, then were at least close to paradigmatic examples of what it is to think clearly and logically about such-and-such.

Thus, to conclude, regardless of what I’ve said above (if it doesn’t “ring true” to you), I do think that your “distrust” of logic might be something to pay closer attention to, and I also feel that no matter how clear and crisp a thinker you might be, there can be no harm done but only possible improvement to your abilities as a “logical” thinker if you take the time to explore SL. Moreover, learning to think and express yourself in logic needn’t stifle any creativity or spontaneity—it certainly hasn’t made me any less absurd!

I think that Lurid has got it pretty much correct when he says, “…it should be noted that people often use ‘paradoxical’ to mean ‘counter intuitive’, whereas in logic these sorts of terms are much stricter in meaning.” I think that the general or common sense of ‘paradox’ is akin to ‘counter intuitive’. However, on analysis, contradiction, paradox, absurdity, and binary pairs all come out to be the same sorts of things. This is part of the work that I’ve been doing for the last few years.

Looking to the Oxford Dictionary of Current English we find:

paradox n.. 1a seemingly absurd or contradictory though often true statement.

As far as I am aware, logic simply doesn’t deal with paradox; that is, in any logic I am aware of there is neither definition of paradox nor rules or procedures to deal with it. This is likely because in logic a paradox is going to be translated as a strict contradiction—a clear violation of the law of the excluded middle. This is our P & ~P. I mean, look at some of the more common paradoxes:

1) We have the Schrodinger’s Cat Paradox manifesting as the paradigmatic example of the superposition of quantum states: the cat is dead & the cat is alive.

2) We have the classic paradoxes of Zeno. The Arrow shows that a moving object can’t be moving, Achilles and the Tortoise (and its variations) show that Achilles can never catch the tortoise even though he is clearly a faster runner than it; or, Achilles cannot even start the race because there is always half the distance from him to the next step.

Clearly, in these sorts of paradoxes their symbolic representation is going to be our P & ~P.

Thus, it appears more like we call some occurrences of P & ~P paradoxes simply because they seem as necessary contradictions for our very phenomenal existence, whereas if we don’t have to hold a contradiction out of necessity, then we seem somehow happier to call them “absurdities,” or “contradictions,” or “impossibilities.”

…there is a continual desire to reach an absolute point of clarify and understanding of the world

For some, yes—anyway, I find the phrasing here particularly poignant to the issue in at least a few ways. Notice the “paradoxical” or if you prefer, “contradictory” nature of the metaphor being employed (also note that this isn’t a criticism towards you, Tom, but merely noting the way that most of us would commonly phrase a similar linguistic structure to convey a similar meaning). ‘Continual’ juxtaposed with ‘point’; that is, continuity with discreteness as a binary pair. We also have, although a little deeper and more implicit, two further pairing: {Self, Other} and {Immanent, Transcendent}. The {S,O} pair is generated when we recognize that this “continual desire” has to be a desire that someone holds—a Self; and, the Other stems from the v. fact the desire is directed towards understanding “the world”—understanding the Other. The {I, T} pair is even more abstract. Since we are looking for an “absolute” we are looking for something unchanging—eternal and fixed. Now, without getting too into it, these are qualities associated with something that must necessarily transcend the changing and fluctuating world. Solutions and understanding regarding the world are formulated within the world, and so, are immanent to it.

The terrible danger is that we collapse reality down to an unrealistic and absolutist view in a desperate attempt to reconcile contradictions in our thought…

No doubt! Much of the work that I’ve done in my investigation and analysis of the “contradiction, paradox, duality (binary pairings), and absurdity” connection has been not to resolve, banish, or degrade these things, but to express their apparently central and integral role in the construction/invention of our phenomenal experiences. Embrace not shun!
 
 
Chill
22:29 / 26.07.03
An excellent book on that touches on symbolic logic/ propositional calculus and the"strange loops" and paradoxes that arise from formal systems, is Douglas R. Hofstadter's book Godel, Escher, Bach: An Eternal Golden Braid.

Contradictions seem to be useful for finding "flaws" within a given system, requiring a re-evaluation of the system and forcing the evaluator to jump out of the current system and view it from a "higher" level (possibly why contradictions seem to be popular in zen koans). The ability to jump out of levels, operate on different levels interchangeably and percieve when moving to ever "higher" levels would be futile, could arguably considered one of the cornerstones of "intelligence".

In my view contradiction is more than a "helpful tool for interpreting our reality" and more like an essential tool for percieving a reality. .

The statement below is false,
The statement above is true.
 
 
Tom Coates
13:05 / 31.07.03
Notice the “paradoxical” or if you prefer, “contradictory” nature of the metaphor being employed (also note that this isn’t a criticism towards you, Tom, but merely noting the way that most of us would commonly phrase a similar linguistic structure to convey a similar meaning).

Except that's not actually a paradox or contradictory - it's a statement that the process of aspiration towards absolutism is continual and ongoing - a desperate attempt to find a closure on thought (cf. "The End of History") that's inevitably impossible to achieve.
 
 
—| x |—
20:14 / 31.07.03
Except it is. A continuous process traces out a line through the structure of space-time. The absolute is a point of perfection—a singularity if you will; thus, the absolute is removed from space-time as we can experience it and is a non spatial and non temporal object—transcendent of any possibility of our strivings. An absolute creates an asymptote: the world line of any given human might sneak closer and closer to that elusive absolute along a line going to infinity, but no human—no matter how great—can actually exist as/within/in tandem with, or etc. the singularity because our lives are structured within the greater structure of space-time and singularities are shielded from our phenomenal experience of space-time via an “event horizon.” Put differently, the actual achieving of the absolute cannot be accomplished in a manner such that a person can “cross-over” once s/he has been to the other side.

Again, a continual process striving towards a singular end, or rephrased, a fluctuating path traced out over time in space which intends to connect with the unchanging, the eternal—that which is by necessity transcendent of space-time: seems like P & ~P to me.
 
 
Quantum
10:57 / 01.08.03
If the Zen 'Mu' unasks the question, can it also unRage a thread?

I agree with Chill, GEB pretty much reflects my opinion- if you can show a contradiction in a system it forces you to go a level up in a way, as it shows the system to be inconsistent- to impose consistency on it we try to formulate a broader system encompassing and explaining the inconsistency.
 
 
Tom Coates
13:51 / 01.08.03
Well I could say that continual does not necessarily mean infinite, which is true. Or I could say that the fact that the latter point is a fantasy that can never be truly achieved means that it's quite possible to continue indefinitely while still aspiring to an end - which would also be true. It would only be a paradox if that final absolute point was achievable.
 
 
—| x |—
22:57 / 01.08.03
Well I could say that continual does not necessarily mean infinite, which is true.

Yes, true in a sense for sure. But, on the other hand, I could say that in any finite continual interval we can also have an infinity bound in this interval, which is also true. I could also say that, even while our lives are finite, our striving towards the absolute places us on a necessarily infinite trajectory.

Or I could say that the fact that the latter point is a fantasy that can never be truly achieved means that it's quite possible to continue indefinitely while still aspiring to an end - which would also be true.

Agreed (as per my last sentence). However, willfully striving for an end which is infinitely removed while realizing that it is infinitely removed again appears to require that we hold an implicit contradiction of some sort. Perhaps, “I will have that & I can never have that.”

It would only be a paradox if that final absolute point was achievable.

Again, not necessarily (as per my last sentence). It is a paradox, it seems to me, depending on how we look. Kinda’ like this.
 
 
Groman
01:41 / 01.09.03
Hi,
I just wanted to drop a few things in here, since I've made my living for the past couple of years teaching logic.

Anything follows from a contradiction
Here's a very simple proof strategy of the point. It requires only two rules involving the truth conditions for the word "or."

Rule 1: If P, then P or Q.
(If some sentence P is true, then it is truth that either that sentence P is true or any other sentence, Q, is true.)

Rule 2: If P or Q, and not-P, then Q.
(If it is true that either P is true or Q is true and P is in fact false, then Q must be true.)

Given these two rules, anything follows from a contradication.

1. X
2. not -X
3. X or "There's a million dollars in my pocket." (By Rule 1, line 1)
4. There's a million dollars in my pocket. (By Rule 2, lines 2 and 3)



Contradictions and Human Inquiry
Some of you have mentioned contradictions in metaphysical terms. Although I'm a philosophy, and cannot give the best elaborations of these points, I know of at least two significant examples from science and math.

The best science example I know is the inconsitency between the quantum mechanics and general relativity. I believe this goes to the distinction between the quantum view of matter and energy as existing in discrete states and the general relativity view of continuous values of matter and energy.

The math example has to do with infinitesimals. These are supposed to be real numbers that are smaller than every other real number except 0. I believe that the contradiction involves the theorem that for any two real numbers (so also for 0 and any infinitesimal) there exists a number in between them. Thus, any number that is supposed to be an infinitesimal number should actually have a number smaller than it.

I don't think we need to get all metaphysical when pondering the role of contradictions in human thought. Whenever there are two different attempts to understand the same system, they can make different idealizations and abstractions about those systems (see the science example above). Therein lies the rub, because one system might emphasize a detail while the other minimizes it. If both attempts return useful results and you want to accept both theories, you open yourself up to embracing a contradiction.
 
 
Quantum
13:21 / 01.09.03
Rule 1: If P, then P or Q.
(If some sentence P is true, then it is truth that either that sentence P is true or any other sentence, Q, is true.)

I'm sorry, I'm just not getting this. Is it logically equivalent to 'If P then P, if not-P then Q'?
Why Q if not-P? Doesn't that make Q necessarily the contradiction of P?

Just to illustrate my ignorance, let P=cats have hair. So,
If cats have hair, then cats have hair or Q.
Where's the Q come in?
 
 
Quantum
13:28 / 01.09.03
Ah, wait, I see now. The rule is at fault. By adopting it you assert a paradox, kinda like the cretan liar. 'If P is true, then P is true or something else' to me denies 'If P is true then P is true' which I hold to be undeniably the case, as a tautology should be.
 
 
Lurid Archive
14:04 / 01.09.03
No, the rule is ok Quantum. The superfluous bit doesn't invalidate it.

If cats have hair, then cats have hair or Q.

Where's the Q come in?

It doesn't affect the validity of the statement, so you can include it without destroying your tautology. Let go your common sense...
 
 
Tryphena Absent
15:26 / 01.09.03
Basically Q is the valid alternative to P. So if P is false than Q has to be true in light of the sentence.
 
 
Lurid Archive
17:07 / 01.09.03
Errrmmm, no. This is the mistake that everyone makes. The statement is, "If P, then P or Q". If P is false, it says nothing about Q. The implies truth table takes a little getting used to.

"If the moon is made of cheese then my name is Lurid"

and

"If the moon is made of cheese then my name is not Lurid"

are both true statements. (Assuming that the moon isn't made of cheese.) The idea is that the conditional never bites as the first proposition is false.
 
 
Tryphena Absent
08:35 / 02.09.03
Hang on, the argument stated that if P was true then P or Q had to be true. If P isn't true than the 'or' is invalidated and the whole proposition fails because the 'or' being the logical conditional is the most important part of that sentence. So sorry what I meant to say is if the second P is false than Q has to be true in light of the sentence.
 
 
Quantum
09:00 / 02.09.03
OK, I've got it in terms of logic- Q is superfluous. Thanks, Lurid.

But still getting used to the meaningful equivalent. The Q doesn't come into it at all, like a logical appendix or vestigial tail. Since the conditional never bites (and never can) Q can never be proven true or false.

To continue my example above, if cats are hairy then not-Q. If cats are not hairy then the rule doesn't apply, so still not Q.
Is that right?
 
 
Quantum
09:08 / 02.09.03
if the second P is false than Q has to be true in light of the sentence.
Same P, if it's false then the first part ("If P") is unfulfilled, and as you say the whole proposition fails. I think...
 
 
—| x |—
20:39 / 05.09.03
"I don't think we need to get all metaphysical when pondering the role of contradictions in human thought."

Well really, we needn't even get out of bed in the morning, right?



What I mean is no, we needn't get "all metaphysical" when discussing the role of contradictions in our lives; however, I tend to think that some sort of singularity is the ontological foundation of thsi (and other possible) worlds, and that this singularity is necessarily a contradiction. Therefore, we are not being airy-fairy metaphysical (like yer turn of phrase implies), but seriously "deep structure" like wrt ontology!

And, perhaps this was said already but I missed it in the quicl scan over the logic stuff.

The rule about a disjunction (or 'or' for you non-logic speaking folks--it looks like 'v' btw) is what allows for the adition of the Q, sorta', and then results regarding the truth table for implies carries over (as it becomes the conector with the greatest scope) carries over to give the same results. Look:

The truth conditions for a disjunction, P v Q, are that it is a true statement so long as at least one of its disjuncts is true, and false if both P and Q are false. So if we are assuming something is true, say, P, then we can add any statement (or series of statments) at all to it, and the sentence remains true. For an concrete example:

1. If I am a man, then I am human, the moon is made of cheese, hamburger is made from people, there really are forty-five foot gators living in New York's sewer system, or your mother was Charles Manson.

1. is a true statment unless it is false that I am human and true that I am a man and its truth-conditions do not in anyway depend upon the trash that is attached.
The above
 
 
Groman
16:06 / 06.09.03
Sorry for ducking in and then not responding to others' posts, but people were getting fired at work this week and I'm one of the new guys. (Luckily, I dodged a bullet this time.)

Actually, in order for what I said to make sense, as well as to make sense of the whole idea of anything following from a contradiction, we have to discuss the idea of deductive validity. This is a property of arguments, which are a set of premises (possibly none) and exactly one conclusion.

An argument is valid if it is impossible for the premises to be true and the conclusion false.

This idea of impossibility is tricky.

Sentences are generally understood to derive their truth values from (1) their syntactic (i.e., logical) structure, (2) the meaning of their component terms, and (3) the relationship(s) between the component terms and the things in the world to which those terms refer.

An argument is valid if, based on a fixed interpretation of the logical and semantic parts, there is no possible arrangement of the things mentioned in (3) above, which would make the premises true and the conclusion false.

So, let's look at If P, then (P or Q).

It's a deductively valid argument if there is no way that the premise (P) could be true while the conclusion (P or Q) is false. As has been mentioned in posts above, (P or Q) is false only if both P is false and Q is false. But, then it is impossible for P to be true and (P or Q) false. So, the inference is valid.

"Everything follows from a contradiction" plays off of this definition of validity. If your premises contain a contradiction

(P, Q,..., not P,...)

then, because P and not-P cannot both be true ( because P is a single sentence and ‘not’ reverses its truth value), it is impossible for all the premises to be true. Therefore, whether the conclusion is true or false, it will be impossible for the premises to be true and the conclusion false. Thus, any argument with a contradiction in the premises is valid by definition.

Now, all arguments can be represented as a conditional (i.e., If [premises], then [conclusion]). So, if you plug contradictory premises in, it will be impossible for the If-clause to be true. So, the conditional itself is necessarily true, because you can never have the true premises necessary for a false conditional.

Now, if you think about it, there’s no consequence to this for what the world is like because it is impossible for the premises to be satisfied. So, plug in whatever you want as the conclusion, it “follows” from the premises logically, but has no effect on it being true or false in the world because the premises will never be satisfied.

So, this is why it is safe for us to say that anything follows from a contradiction, because (by definition) a contradiction could never be actualized.

Sorry about the "all metaphysical" comment. What I meant to express is that contradictions are very common.

I would have to say, though, that the fact that we aren't all dead as a result of valid, yet defective, reasoning from the contradictory beliefs hidden somewhere in most of our minds indicates that logic doesn't actually represent the basic patterns in human thought.
 
 
—| x |—
03:32 / 07.09.03
I would have to say, though, that the fact that we aren't all dead as a result of valid, yet defective, reasoning from the contradictory beliefs hidden somewhere in most of our minds indicates that logic doesn't actually represent the basic patterns in human thought.

Aye, ya’ cheeky bugger!

I think there is certainly myth—or perhaps better mythos—to the idea that our goal as humans is to become “perfectly rational beings”--*cough* bullshit etc.. The logic, reason, validity and such are aspects of a mode of coping with certain relationships we have with things; however, we have more than merely such “logical” relations with the world and modes of coping with it.

So, this is why it is safe for us to say that anything follows from a contradiction, because (by definition) a contradiction could never be actualized.

Ah yes, but we define to live and live to define! What I mean is, imagine if you will a singularity that is at once nothing and everything. This strange but real object can’t exist but it does because it is and isn’t all at once. Now, since it is all that and a bag of chips rolled in a comfy, ahem—empty—nirvana it can’t be, so what become actualized are fragments. Fragments exist iff space exists, but structures of spacetime are relative to the fragments constituting them; thus, there is not merely a spacetime, but many spacetimes. So, everything follows from a contradiction in actuality, but since it is we who can’t exist in such a state we occupy but some small set of fragments each with their spacetimes arising through interactions with other fragments. So we are back, by my lights (which admitedly get dim at this sort of depth), at a contradiction as the single ontologcial object within which and stemming from we are (note to reader: for best effect read that last bit as if it was spoken by Yoda).
 
 
CaseK
12:12 / 07.09.03
I'm not following that ostensible contradiction too well, but it does seem to me that you're now asserting that everything (i.e., all extant things) is in fact _derived_ from a contradiction, which is a much different claim from the logical notion that _anything_ (i.e., any logical propostion) is _derivable_ from a contradiction between logical terms. The latter has to do with the workings of & conventions surrounding a set of rules & axioms, while the former is a claim about *ponders* um, maybe the creation or origins of things in the world, I suppose. Not sure. Anyhow, there is no clear reason that I can see for positing any relationship between the logical claim and the "world claim"; it's certainly not the case that the logical claim somehow licenses the "world claim," which then means that the "world claim" stands to be evaluated on its own. Which makes it seem, to me, quite mysterious.
 
 
—| x |—
22:12 / 07.09.03
"...you're...asserting that everything (i.e., all extant things) is in fact _derived_ from a contradiction, which is a much different claim from the logical notion that _anything_ (i.e., any logical propostion) is _derivable_ from a contradiction between logical terms."

Yes--and, well, no. Yes, I certainly am making an ontological claim here; however, what we must be clear upon is the underlying premise that "reality" is a function of our relations with things. That is, since "logic," "reason" and etc. are fundamental to our interpretation of these relations it follows that what composes our "reality" is modeled, created, sustained (in part) by these functions. Therefore, while the two claims are different claims there is an apparently close and relational connection between the claims. Put differently, we realize that within the structure of our reasoning anything follows from a contradiction & since our "reality" is ontologically a collusion of relations which are in turn interpretted by us (and any other thing) this structure of our reasoning is holographically (to use a buzzword) relational to the structure of the world. Differently still: there is no separation between mind and matter.

Mysteries abound, friend & truth is stranger than fiction.

 
 
CaseK
22:49 / 07.09.03
I would disagree with that. "Anything follows from a contradiction" is merely true by convention -- I don't see any reason to conclude that this convention maps any aspect of actual, real-life reasoning. This is similar to the (false antecedent --> false conclusion) conditional being conventionally defined as true: another "artifact" of formal logic that has no real correspondence with the way people reason.

For that reason, I do not think it is right to say that within the structure of our reasoning (i.e., in the way we actually reason in daily life, vs. formal logic), anything at all (much less _everything_) necessarily follows from a contradiction. There is no reasoned relationship between a contradiction and what it entails -- that is to say there is no chain of reasoning that takes one from a contentful contradiction (vs. one represented in formal notation) to random, unrelated conclusions. Even if I deploy many of the formal logic's rules of inference in my reasoning, there is no need to assume or stipulate that I deploy/respect _this_ convention.

My holding two contradictory beliefs implies somewhere between very little and nothing at all about what exists in the world (especially about what exists apart from my narrow personal view of it), and it has similar implications for the rest of my belief system. It's true to say that we need logic & reason to get a grip on the world, and that these influence how we understand that world. But I don't think that entails the claim that every single convention of formal logic is mirrored in our actual reasoning & thus has implications for ontology & reality as we understand it.
 
 
Bomb The Past
01:24 / 08.09.03
Dr.~(c^2)>0 is beginning to remind me of everyone's favourite dialectician, GWF Hegel, but on 'shrooms (I mean that in the nicest possible way). Which reminds me, no-one has explicitly mentioned dialectics yet, which seems odd considering it is a logical system that actively embraces contradictions.

My understanding of dialectics is more than a little shaky but this is what I think the idea is: dialectics works by the proposal of a proposition (the thesis) which is contradicted (by the antithesis) but instead of abandoning the contradiction a synthesis is reached. I'm pretty sure that Kant argues that reason can be used to "prove" a number of contradictions, such as, the world is both limited in time and space and it is infinite, or an absolutely necessary being both exists and does not exist in the world. This he takes to be an indication that we can never know things-in-themselves (noumena) but only appearances (phenomena).

Hegel however thinks that contradictions are inherent in reality, and they're not really a big deal. To take a modern example of what some regard as a contradiction, light is a particle and light is a wave. If Hegel were still around he might repeat this little snippet, "...neither of these determinations taken alone, has truth; this belongs only to their unity. This is the true dialectical consideration of them and also the true result."

So, to get to the point, I don't think it would follow from a dialectical point of view that any proposition can result from a contradiction, but in another sense it would follow that every true proposition does follow from contradictions because the universe is comprised of contradictions.

Now all that depends on your take on dialectics of course. I'm reading Popper's Conjectures and Refutations at the moment and he's pretty damn scathing about Hegel and dialectics in general. It all kinda revolves around your take on whether a contradiction is P & ~P or can be taken in a wider sense. The second option brings with it all manner of sticky problems to do with false oppositions and such like which would have deconstructionists wetting themselves. Though I must admit I am drawn to the aesthetics of it a bit more than formal logic's take on events.
 
 
CaseK
14:45 / 08.09.03
But as far as I can make out, that whole Hegelian point presupposes that there are ontological or rational consequences which mirror (and/or are somehow licensed by) the formal logical consequences at issue, and I can see no reason to suppose that this is the case. Even if we allow that light's being both particle & wave is loosely a "contradiction," I don't think it's the case that all true propositions, or even all true propostions about light, follow from or arise from this "contradiction." I can't see how one might even begin defending that claim. At best, I think one might argue that since this "contradiction" somehow entails all propostions, period, it coincidentally also entails those true ones. But this seems to me to be a very "meh" claim, one that's not terribly interesting beyond being a reiteration of formal logic's rules about contradictions. These other claims about light or the world at large don't "follow" in any interesting -- i.e., reasoned, defensible, open to critique, & c. -- sense.

Nor does it seems sensible to me to say that all true propostions arise from some collective of contradictions in the world. This is akin to saying that these propostions are unconnected to reasoning of any kind, since a contradiction -- in self-denial -- asserts nothing at all. This disconnects truth from virtually all conventional philosophical & logical metrics, which is an option, surely, but I don't think it's a very prudent one if one wants to keep talking meaningfully about truth to people other than mystics.

Also, it's a big leap from formal logic's claim that contradictions entail whatever takes your fancy to the claim that ontological "contradictions" entail _only true_ propostions; I don't think this leap can be made without some substantial argument, and I can't presently imagine what shape that argument might take.

Whatever contradictions there might be in the world, and even granting that our beliefs & intersubjective judgments do most of the work of crafting "objective" reality, I am still deeply unclear as to how contradictions in either belief or fact are supposed to license or give rise to the kind of rational -- much less _ontological_ -- free-for-all which would be the case if the formal conventions surrounding contradiction applied to everyday reasoning.
 
 
CaseK
14:57 / 08.09.03
I wanted to add that I am A-OK with the dialectical idea of "truth" emerging via struggle between opposed forces, some of which forces might amount to a contradiction in the loose sense. However, this strikes me as an idea wholly apart from formal logic's notions re: contradiction. Dialectic is, as I understand it, a kind of winnowing, a back-and-forth exchange that generally presses forward in understanding. This is not at all what happens between logically contradictory terms.
 
  

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