POLL on the logical validity of an argument on Joe being a squid

[Speakpigeon]

To be more precise, I claim it is a correct one. There are equivalent, also correct definitions. But let's go with that one - or with your preferred definition; it still works.


That is very ambiguous, but I will try to address that:

First of all, I did not claim that mathematicians or logicians or philosophers generally give a justification for a claim that this definition is the correct one. But we need to back up a little bit. First, what is for a definition to be correct? It is to match usage, right?

But surely, the definition is correct for for mathematics, logic, philosophy, and science, because it matches the way "valid" is used in those fields (nearly always, at least; for example, for the case of philosophy; there are more specialized fields of philosophy, logic or math in which a number of different definitions are used, so as to study different types of logic, in some sense of the word). I claimed that it is correct for those fields. Is that what you want me to provide evidence of? I can do it if you like. For example, for logic, I already provided the link to the Wikipedia article on that, but I can find sources for math, more for logic, sources for philosophy, etc., though I'd rather not do that until you tell me that this is what you are asking, because otherwise there is a risk I spend time finding the evidence and then you will tell me that it is off-topic.

Now, I did provide an argument for why the property of arguments consisting in taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false is very important in mathematics, logic, science and philosophy. When a property of arguments is very important, it is often useful to give it a name. In this case, the property in question is named validity.

And if you already provided this justification, please remind me in which of your posts you did.

I will remind you that in this post I provided a good justification as to why the property of taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false is so important in mathematics. I also briefly explained here why that property is also important in science and philosophy, but let me elaborate: Since science uses mathematics extensively, and validity so defined is so important in mathematics, it is so in science. For example, physics papers are usually full of math, and the same points I made here for math papers, hold for the vast majority of physics papers as well.

What about philosophy?
Well, philosophers are concerned about finding truth in different settings, and generally, knowing whether an argument has a form such that it is impossible for the premises to be true and the conclusion nevertheless to be false, is very useful indeed. As a matter of fact, and just as in the case of mathematics, a philosophy paper would be rejected if it has a deductive argument that fails to have the property of taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false, whereas at least in the vast majority of philosophical contexts, an argument that does have the property of taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false will only face objections to one or more of the premises - or directly to the conclusion, but implying that at least one of the premises is false -, but there will not be an objection as to the acceptability of deducing the conclusions from the premises.

Similar reasons hold for logic.

In sum, in the fields of mathematics, logic, philosophy and science, the property of arguments consisting in taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false is very important. Now, when a property is very important in a context, it it often the case that the property in question is giving a name. There are good practical reasons for this; for example, in the specific case of the property of arguments consisting in taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false, it is far shorter and less cumbersome to talk about valid arguments and the validity property.

So, in sum, that provides good grounds for giving the property of arguments consisting in taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false (or trivially equivalent properties) a name. As it happens, the name in English is "validity" - as you can see by looking at obviously equivalent definitions given in books specialized on those fields -, at least leaving aside some smaller subsets of philosophy, logic or math where other, non-standard forms of logic are studied.

Now, what else do you want? Are you asking whether that definition of validity matches common usage among English speakers with no formal training?

That is more difficult to say, but it seems that validity - like other technical concepts - is one of those concepts in which lay speakers yield to experts in the relevant fields for the definition. But before we get to that, I would like to know what your objections to my previous points in this post are, if any. If you have objections, I will address them first, before I give more arguments on the matter. If you do not object to the above, then please let me know, and also let me know what it is that you want me to justify. Is it a claim that the colloquial usage of "valid" matches the concept used in math, logic, philosophy and science? Is it something else?

What I understand of your logorrhea is that your own justification for accepting the definition as correct is that it is the one used by mathematicians.

First, you think I don't know that?! Whoa.

Clearly, this definition is important to mathematicians. So?! The possibility to torture opponents is important to dictators. Is that's any reason we should follow them?

Second, are we mathematicians here?! Most people here definitely not.

Third, I asked whether the argument was valid, not whether mathematicians would say it is valid or not.

Fourth, your reply doesn't answer my question. Read again: What is the justification given by mathematicians, logicians, philosophers etc. that would support your claim that this definition of logical validity is the correct one?

OK, I think I can surmise your expertise with respect to the substance of my question as zero. So, we can leave it there. You've explained what you understand and, well, it's not enough, and then you're unlikely to be able to improve it given your dogmatic frame of mind.
EB

 

[Speakpigeon]

Many moons ago here on this board (or two or three board ownerships ago), there was a lively discussion where it was argued that although all inductive arguments are nondeductive arguments, not all nondeductive arguments are inductive arguments. Also, and seemingly unrelated, I would fiercely defend the notion that not all non valid arguments are invalid arguments. The strength of argument trumps lexicographer’s dart throwing pot shots at explanatory statements about what words mean.

People have ridiculed inductive arguments as being a type of failure when in fact they are not; each is like a tool with its own purpose, and what an inductive argument is used for is not a failing merely because it doesn’t perform how a deductive argument is designed to.

In order for the categories of deductive and non deductive to be collectively exhaustive, something is required, and it centers around the guarantee of a conclusion to be true under certain conditions. The definition cited, “taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false” is an explanation. An explanation! Someone wrote that, and they used words, and it’s insightful, but it’s still an explanation—and a good one. It’s not just about reporting usage but about keeping the bubbles out—like air bubbles in an oxygen tank underwater. They used the word, “impossible.” That was to preserve the exhaustivity between deductive and nondeductive arguments. The writer didn’t have to use the word, “impossible,” but he did, and it does a fine job of doing what was needed to be done—preserving an essential element that separates the deductive argument from the nondeductive argument.

Deductive and inductive leaves room for bubbles to escape. That’s an A versus B situation. Deductive and non deductive is an A versus not A situation. Collective exhaustivity intact!

When we turn to a dictionary as our trusted source for what “invalid” means and it says not valid, that’s a darn good EXPLANATION that the lexicographers have given us to explain its usage, but remember, argument trumps! It’s fine as explanations go, but it’s inadequate and fails to account for the seeping bubbles. In what land is a nondeductive argument valid? It must be in the same land that gives anyone a reason to think a conclusion to a deductive argument can be valid. Pure hogwash!

Validity speaks only to deductive arguments and only to its form. Not conclusions and not nondeductive arguments. But but but, what about all these various definitions drooling about with different words? They might very well reflect usage, and it does a decent job at giving us a cursory understanding, but there’s a reason we gravitate towards definitions like this that pop out of technical fields—because they preserve the integrity of what they’re meant to.

We're only talking about a deductive argument here, and a deductive argument is either valid or not valid, no other possibility. So, if not valid then invalid. Not valid and invalid in the case of a deductive argument mean the same.

If what is presented as a deductive argument doesn't make sense then it is not a valid deductive argument, and so it is not valid, and therefore it is invalid.

So, by the way, that makes 7 votes for not valid against only one vote for valid.

Mathematicians apparently got a severe beating here.
EB

 

[fromderinside]

I see. A tree is a tree so let it be. Not even deductive, just tautological. You am what you am you say.

 

[fast]

If dogs bark, cars eat dog food.
Dogs bark.
Therefore, cars eat dog food.

Does that make sense?

 

[Speakpigeon]

If dogs bark, cars eat dog food.
Dogs bark.
Therefore, cars eat dog food.

Does that make sense?

Yes, it does. It's another of the small number of pet peeves I have with the logic of university establishment. Typically, people like here will say that a sentence makes sense if it successfully refers to a state of affairs of the real world. So, saying the Earth orbits the Sun would make sense, according to this view, only because it is in fact true that the Earth orbits the Sun.

But this is idiotic. It is a fact that we can all understand your dogs bark argument and no problem. We could even translate into Russian, Chinese and what not. Obviously, we are all going to have to admit that we believe there is no such thing as a car eating dog food. Yet, we can read the argument and accept that it is valid. If not, then no argument would be valid unless you plugged in an interpretation of the lexical terms that made the premises true, and then what on Earth people who discussed logic for centuries would have been talking about? Nonsense?

This is just plain absurd. A statement makes sense not because it refers to an actual state of affair but because you seem to understand what it means, which in effect is just you making sense of it, you being able to form a meaning in your own mind, and real-world references be damned. If you don't accept that, then people could only make sense if they possessed knowledge, which often they don't.

Think of a religious community. They keep talking to each other about God and angels and Heaven and Good and Evil. A big chunk of what these people talk about is straightforwardly non-referring, i.e. it doesn't refer to any actual state of affair any human being knows of. So according to the positivist dogma, this is nonsense. Is it? How come these people could keep talking to each other and appear to understand each other if what they say didn't make sense?! This is properly absurd and a result of the same dogma prevailing in a large chunk of the population of scientific workers and the scientifically literate.

And of course, any logical formula, for example, "If A and A implies B, then implies B", would be nonsense as well since A and B don't refer to anything.
EB

 

[fast]

Not that this is relevant, but it’s a mistake to think a term with no referent is therefore a nonreferring term.

Words that cannot refer are nonreferring terms (eg, the word “although”).

Terms that fail to refer merely because the intended referent does not exist are still referring terms. For instance, if there are no ghosts, the term “ghost” is a referring term that fails to refer. The failure to refer is insufficient to regard it as a nonreferring term.

The word, “although” has a usage and thus has a meaning, just as the word, “ghost” has a usage and thus a meaning. The difference that makes the word “ghost” a referring term and the word “although” a nonreferring term rests not with the non existence of a referent but rather whether or not it would succeed to refer if what was attempted to refer to exists. There cannot possibly be a referent to “although,” but if there were ghosts, the term would successfully refer while if there are no ghosts, it’s nevertheless a referring term but one that fails to do so.

 

[untermensche]

If dogs bark, cars eat dog food.
Dogs bark.
Therefore, cars eat dog food.

Does that make sense?

No.

A premise must be something that makes sense, not only the structure, to build anything from it. It must be shown to be possible.

Cars cannot eat anything.

To have a premise saying they can defies any sense.

It is nonsensical.

 

[fast]

If dogs bark, cars eat dog food.
Dogs bark.
Therefore, cars eat dog food.

Does that make sense?

No.

A premise must be something that makes sense, not only the structure, to build anything from it. It must be shown to be possible.

Cars cannot eat anything.

To have a premise saying they can defies any sense.

It is nonsensical.

It’s quite different from:

If dogs bark, vicarious drinks proclivity.
Dogs bark.
Therefore, vicarious drinks proclivity.

In the former, we can make enough sense of it to deny that it’s true (like you did). In the latter, it makes no sense such that it’s questionable that it’s even a proposition expressed by the sentence. The former argument has a valid form; the latter, well, perhaps not, as it’s questionable that what even appears to be a premise in fact is.

If the latter is a sentence yet not comprehensible to even to be a statement (that would express a proposition if it was), then we may have good reason to deny that it’s even a premise to begin with.

 

[Angra Mainyu]

What I understand of your logorrhea is that your own justification for accepting the definition as correct is that it is the one used by mathematicians.

My post was carefully written, but no, you do not understand what I meant that the definition in question reflects actual usage by mathematicians, logicians, philosophers and physicists when they work, at least in the majority of contexts.

First, you think I don't know that?! Whoa.

Clearly, this definition is important to mathematicians. So?! The possibility to torture opponents is important to dictators. Is that's any reason we should follow them?

No, you do not understand. It is not that the definition is important to mathematicians. Rather, the property of arguments consisting in taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false is very important in mathematics (and physics, philosophy, and logic). That property is given a name: validity. But even if that were not the name, the property would remain important, because:

a. It preserves truth: as long as you have a form that is a valid argument, true premises result in a true conclusion.
b. It is the strongest property that is truth-preserving, in the sense that other means of deduction that also preserve truth do not allow for all of the derivations that this particular property allows.
c. It is used all the time when thinking of mathematical (and physical) and philosophical arguments.

Second, are we mathematicians here?! Most people here definitely not.

First, not most people here, but this is a logic and epistemology forum, so if you do not clarify, it is understandable that people interpret that the concept is the technical one.
Second, even in good dictionaries, dictionary definitions intended to capture common usage list a number of meanings of "valid" that are not applicable to this particular setting (i.e., validity of a deductive argument), and then they list a technical definition. It appears that at least the most common usage among lay people (i.e., not logicians, mathematicians, philosophers, etc.) of "valid" when talking about a deductive argument is precisely the technical meaning, even if they do not understand it very well. It is like when non-physicists use the expression "black whole" in a non-figurative sense. They do not understand the concept very well, but they are yielding to the experts for the definition.

Third, the definition that you provided while refusing to provide a source is also a technical definition, from the field of logic!. I know that because I found it. It is from the American Heritage Dictionary. And you are right that that is a good dictionary. But take a look at the definition that you yourself quoted:

https://ahdictionary.com/word/search.html?q=valid

Logic. a. Containing premises from which the conclusion may logically be derived: a valid argument.

Once again, no non-technical usage reported (applicable to deductive arguments, that is), given the label "Logic" ( see https://ahdictionary.com/word/howtouse.html ).

Third, I asked whether the argument was valid, not whether mathematicians would say it is valid or not.

First, I did reply. It is valid. You really are failing to comprehend what I'm saying about mathematicians.

Second, I replied that it is valid under the very definition of validity that you provided..

Third, I carefully made the points as to why it is valid (it is Bomb#20's argument) but you just mistreated me again and dodged. Let us go again:


P1: A squid is not a giraffe.
P2: A giraffe is not an elephant.
P3: An elephant is not a squid.
P5: Joe is an elephant.
C1: Joe is not a squid.

I claim that C1 can be derived from the premises, so it is valid by your definition. More precisely, it is derived from Premises P3 and P5. Do you object to that one, or concede that it is valid?

P1: A squid is not a giraffe.
P2: A giraffe is not an elephant.
P3: An elephant is not a squid.
P4: Joe is either a squid or a giraffe.
P5: Joe is an elephant.
C1: Joe is not a squid.
C2: Joe is a giraffe.
I claim that C1 is derived from P3 and P5, whereas C2 is derived from C1 and P4. Hence, by your definition, it is valid. Am I mistaken? If so, why?

Next:


P1: A squid is not a giraffe.
P2: A giraffe is not an elephant.
P3: An elephant is not a squid.
P4: Joe is either a squid or a giraffe.
P5: Joe is an elephant.
C1: Joe is not a squid.
C2: Joe is a giraffe.
C3: Joe is not an elephant.
I claim C1 is derived from P3 and P5, C2 is derived from C1 and P4, and C3 is derived from C2 and P2. Thus, by your definition, it is valid. Am I mistaken? Why?

P1: A squid is not a giraffe.
P2: A giraffe is not an elephant.
P3: An elephant is not a squid.
P4: Joe is either a squid or a giraffe.
P5: Joe is an elephant.
C1: Joe is not a squid.
C2: Joe is a giraffe.
C3: Joe is not an elephant.
C4: Joe is an elephant and Joe is not an elephant.

I claim C1 is derived from P3 and P5, C2 is derived from C1 and P4, C3 is derived from C2 and P2, and C4 is derived from C3 and P5. Thus, by your definition, it is valid. Am I mistaken? Why?

Note that this deduction derives C1 and its negation C3 from the premises, without even using the fact that a anything can be derived from a contradiction - which is what you objected to -, and refuting your previous claim that "And a conclusion and its negation cannot both follow.", which is false, and at this point, it should be obviously false to any reader following the exchange carefully and being epistemically rational about it

So, in order to conclude the argument, one only needs to use the fact that anything can be derived from a contradiction. If that were not the case, it would remain the case that both a conclusion - namely C1 - and its negation - namely C3 - have been derived from the premises. Again, they have been derived without deriving anything from a contradiction.

So, you also object to the last step, namely deriving anything from a contradiction. But then, the definition you provided is about the technical meaning in the field of logic, and in that context, of course one can derive anything from a contradiction, at least going by the most common type of logic by far, or even by intuitionistic logic. You have to choose something like some sort of paraconsistent logic in order to avoid that, so you can say it is not valid under paraconsistent logics.

Fourth, your reply doesn't answer my question. Read again: What is the justification given by mathematicians, logicians, philosophers etc. that would support your claim that this definition of logical validity is the correct one?

Given that I did not claim that mathematicians, logicians, philosophers, etc., give a justification for the definition, and given that nearly all of them are unconcerned with that, your question is out of place.

OK, I think I can surmise your expertise with respect to the substance of my question as zero. So, we can leave it there. You've explained what you understand and, well, it's not enough, and then you're unlikely to be able to improve it given your dogmatic frame of mind.

Bomb#20 got it right again: "Your post is a perfect storm of ignorance and arrogance. It is the Dunning-Kruger effect in action."

 

[Speakpigeon]

Not that this is relevant, but it’s a mistake to think a term with no referent is therefore a nonreferring term.

Words that cannot refer are nonreferring terms (eg, the word “although”).

Terms that fail to refer merely because the intended referent does not exist are still referring terms. For instance, if there are no ghosts, the term “ghost” is a referring term that fails to refer. The failure to refer is insufficient to regard it as a nonreferring term.

The word, “although” has a usage and thus has a meaning, just as the word, “ghost” has a usage and thus a meaning. The difference that makes the word “ghost” a referring term and the word “although” a nonreferring term rests not with the non existence of a referent but rather whether or not it would succeed to refer if what was attempted to refer to exists. There cannot possibly be a referent to “although,” but if there were ghosts, the term would successfully refer while if there are no ghosts, it’s nevertheless a referring term but one that fails to do so.

All this really depends on what the word "reference" refers to.

Words can't do anything by themselves except to exist on the page, on the screen, or inside our mind. So, words don't refer. This notion is a metaphysical expedient devised by people who were obviously not interested in linguistic facts but in the practicality of their little schemes. And now idiots just repeat ad libitum the dogma without bothering to think.
EB.

 

[Speakpigeon]

My post was carefully written, but no, you do not understand what I meant that the definition in question reflects actual usage by mathematicians, logicians, philosophers and physicists when they work, at least in the majority of contexts.

No, you do not understand. It is not that the definition is important to mathematicians. Rather, the property of arguments consisting in taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false is very important in mathematics (and physics, philosophy, and logic). That property is given a name: validity.

What I understood from the logorrhea is that you did not answer my question. And now you are admitting that you won't answer it. So, I suppose it's reasonable to infer that you accept that there is no justification given by mathematicians, logicians, philosophers etc. that would support your claim that the definition of logical validity you use is the correct one. So, in effect, you use a definition and I use a different definition. So, stop pretending you have any expertise that would be relevant to my assessment of the validity of arguments.

But even if that were not the name, the property would remain important, because:

a. It preserves truth: as long as you have a form that is a valid argument, true premises result in a true conclusion.

No. Sometimes it leads to taking false conclusion as true, sometimes true conclusions as false. No good.

b. It is the strongest property that is truth-preserving, in the sense that other means of deduction that also preserve truth do not allow for all of the derivations that this particular property allows.

Like what?!

c. It is used all the time when thinking of mathematical (and physical) and philosophical arguments.

It can be used but it's no good. It works like crutches.

First, not most people here, but this is a logic and epistemology forum, so if you do not clarify, it is understandable that people interpret that the concept is the technical one.
Second, even in good dictionaries, dictionary definitions intended to capture common usage list a number of meanings of "valid" that are not applicable to this particular setting (i.e., validity of a deductive argument), and then they list a technical definition. It appears that at least the most common usage among lay people (i.e., not logicians, mathematicians, philosophers, etc.) of "valid" when talking about a deductive argument is precisely the technical meaning, even if they do not understand it very well. It is like when non-physicists use the expression "black whole" in a non-figurative sense. They do not understand the concept very well, but they are yielding to the experts for the definition.

Third, the definition that you provided while refusing to provide a source is also a technical definition, from the field of logic!. I know that because I found it. It is from the American Heritage Dictionary. And you are right that that is a good dictionary. But take a look at the definition that you yourself quoted:

https://ahdictionary.com/word/search.html?q=valid

Logic. a. Containing premises from which the conclusion may logically be derived: a valid argument.

Once again, no non-technical usage reported (applicable to deductive arguments, that is), given the label "Logic" ( see https://ahdictionary.com/word/howtouse.html ).

This is irrelevant. You're confusing logic with formal logic. Only formal logic is the preserve of whoever spends the time to learn it and then there are different methods of formal logic and we can all set up our own shop if we want. And you've now admitted there is no justification for the definition you use as the correct one, so, in effect you have to admit every shop is legitimate.

And you should look up dictionaries more often, there are plenty of definitions of logic that don't assume it's only a technical term. Further, nobody needs any training to decide for himself whether any argument is valid or not since both the words "argument" and "validity" are ordinary words understood as such. So your argument from the supposed technicality of logic and validity is a non-sequitur. I didn't ask for the validity of a logical formula, I asked for the validity of an argument we can all understand because I couched it in ordinary language, not in technical language.

Fourth, your reply doesn't answer my question. Read again: What is the justification given by mathematicians, logicians, philosophers etc. that would support your claim that this definition of logical validity is the correct one?

Given that I did not claim that mathematicians, logicians, philosophers, etc., give a justification for the definition, and given that nearly all of them are unconcerned with that, your question is out of place.

It is irrelevant you didn't claim it. The point is that you don't know of any such justification, ergo the definition you use is not justified as the correct definition. You just decided on a whim to follow the convention adopted without any logical sound reason by mathematicians. Good to you, I don't and nobody needs to.

OK, I think I can surmise your expertise with respect to the substance of my question as zero. So, we can leave it there. You've explained what you understand and, well, it's not enough, and then you're unlikely to be able to improve it given your dogmatic frame of mind.

Bomb#20 got it right again: "Your post is a perfect storm of ignorance and arrogance. It is the Dunning-Kruger effect in action."

Spare me the gimmick.

Dunning-Kruger effect
In the field of psychology, the Dunning–Kruger effect is a cognitive bias in which people of low ability
have illusory superiority and mistakenly assess their cognitive ability as greater than it is.

Sometimes, I'd be a relief to be an idiot.
EB

 

[fast]

Not that this is relevant, but it’s a mistake to think a term with no referent is therefore a nonreferring term.

Words that cannot refer are nonreferring terms (eg, the word “although”).

Terms that fail to refer merely because the intended referent does not exist are still referring terms. For instance, if there are no ghosts, the term “ghost” is a referring term that fails to refer. The failure to refer is insufficient to regard it as a nonreferring term.

The word, “although” has a usage and thus has a meaning, just as the word, “ghost” has a usage and thus a meaning. The difference that makes the word “ghost” a referring term and the word “although” a nonreferring term rests not with the non existence of a referent but rather whether or not it would succeed to refer if what was attempted to refer to exists. There cannot possibly be a referent to “although,” but if there were ghosts, the term would successfully refer while if there are no ghosts, it’s nevertheless a referring term but one that fails to do so.

All this really depends on what the word "reference" refers to.

Words can't do anything by themselves except to exist on the page, on the screen, or inside our mind. So, words don't refer. This notion is a metaphysical expedient devised by people who were obviously not interested in linguistic facts but in the practicality of their little schemes. And now idiots just repeat ad libitum the dogma without bothering to think.
EB.

I feel ya

I used to ridicule the notion that “words denote meaning” by facetiously characterizing words as being clever little creatures, but the truth taken as a convention dependent truth is a truth nonetheless.

There are truths dependent upon our declarations that they are.

 

[untermensche]

If dogs bark, cars eat dog food.
Dogs bark.
Therefore, cars eat dog food.

Does that make sense?

No.

A premise must be something that makes sense, not only the structure, to build anything from it. It must be shown to be possible.

Cars cannot eat anything.

To have a premise saying they can defies any sense.

It is nonsensical.

It’s quite different from:

If dogs bark, vicarious drinks proclivity.
Dogs bark.
Therefore, vicarious drinks proclivity.

In the former, we can make enough sense of it to deny that it’s true (like you did). In the latter, it makes no sense such that it’s questionable that it’s even a proposition expressed by the sentence. The former argument has a valid form; the latter, well, perhaps not, as it’s questionable that what even appears to be a premise in fact is.

If the latter is a sentence yet not comprehensible to even to be a statement (that would express a proposition if it was), then we may have good reason to deny that it’s even a premise to begin with.

Those that think form means something without function are just masturbating.

To form a true argument takes true premises.

False premises given the same status as false premises is just masturbation.

 

[fast]

It’s quite different from:

If dogs bark, vicarious drinks proclivity.
Dogs bark.
Therefore, vicarious drinks proclivity.

In the former, we can make enough sense of it to deny that it’s true (like you did). In the latter, it makes no sense such that it’s questionable that it’s even a proposition expressed by the sentence. The former argument has a valid form; the latter, well, perhaps not, as it’s questionable that what even appears to be a premise in fact is.

If the latter is a sentence yet not comprehensible to even to be a statement (that would express a proposition if it was), then we may have good reason to deny that it’s even a premise to begin with.

Those that think form means something without function are just masturbating.

To form a true argument takes true premises.

False premises given the same status as false premises is just masturbation.

The validity of form is important, and it says something meaningful about an argument. One, it distinguishes between an argument that guarentees a deductive connection between the premises and its conclusion, and two, in cases of deductive arguments, it shows a trustworthy connection between the presmises and it’s conclusion. Never is it the case that a valid argument, by virtue of it being valid, must yield a true conclusion.

Nondeductive arguments: never valid and never guarentees a conclusion.
Deductive arguments: either valid or not valid (and thus invalid) and when valid and true premises, guarentees the truth of a conclusion.

Two necessary conditions: the form must be valid and two, true premises; that’s a sound (and of course valid) deductive argument with true premises. Both found only in deductive arguments.

 

[untermensche]

It’s quite different from:

If dogs bark, vicarious drinks proclivity.
Dogs bark.
Therefore, vicarious drinks proclivity.

In the former, we can make enough sense of it to deny that it’s true (like you did). In the latter, it makes no sense such that it’s questionable that it’s even a proposition expressed by the sentence. The former argument has a valid form; the latter, well, perhaps not, as it’s questionable that what even appears to be a premise in fact is.

If the latter is a sentence yet not comprehensible to even to be a statement (that would express a proposition if it was), then we may have good reason to deny that it’s even a premise to begin with.

Those that think form means something without function are just masturbating.

To form a true argument takes true premises.

False premises given the same status as false premises is just masturbation.

The validity of form is important, and it says something meaningful about an argument.

It becomes meaningless when a false premise is given the same status as a true premise.

You cannot reach any truth with that even if you follow form. The conclusion is as false as the premise.

You are merely playing around.

 

[fast]

The validity of form is important, and it says something meaningful about an argument.

It becomes meaningless when a false premise is given the same status as a true premise.

You cannot reach any truth with that even if you follow form. The conclusion is as false as the premise.

You are merely playing around.

Validity isn’t supposed to be a sufficient condition for a guarentee to a true conclusion. It’s a necessary condition.

It’s like a sliding board at a theme park. The route is supposed to lead to the pool below. No water on the slide, no splash at the end, but that’s not the point. To say of a deductive argument that it’s valid is simply to have a proper directional flow.

 

[untermensche]

The validity of form is important, and it says something meaningful about an argument.

It becomes meaningless when a false premise is given the same status as a true premise.

You cannot reach any truth with that even if you follow form. The conclusion is as false as the premise.

You are merely playing around.

Validity isn’t supposed to be a sufficient condition for a guarentee to a true conclusion. It’s a necessary condition.

It’s like a sliding board at a theme park. The route is supposed to lead to the pool below. No water on the slide, no splash at the end, but that’s not the point. To say of a deductive argument that it’s valid is simply to have a proper directional flow.

I was agreeing with: "The validity of form is important".

 

[Angra Mainyu]

So, I suppose it's reasonable to infer that you accept that there is no justification given by mathematicians, logicians, philosophers etc. that would support your claim that the definition of logical validity you use is the correct one.

No, that is an unreasonable assessment. Most mathematicians (for example) of course do not look for a justification of the definitions the terms they use. They just use the term. Some philosophers would give justifications, but the point is that I already gave a justification.

So, in effect, you use a definition and I use a different definition. So, stop pretending you have any expertise that would be relevant to my assessment of the validity of arguments.

I do not pretend. I do have expertise - not much, but not much is needed. I already gave a justification.

But even if that were not the name, the property would remain important, because:

a. It preserves truth: as long as you have a form that is a valid argument, true premises result in a true conclusion.

No. Sometimes it leads to taking false conclusion as true, sometimes true conclusions as false. No good.

Not only is your answer false. It is absurd, and to a reader following the exchange rationally, it would be patently absurd. The property we are talking about is the property of arguments consisting in taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false. So, obviously, clearly, evidently, by the very definition, my claim that validity so defined preserves truth is true. As long as you have a form that is a valid argument, true premises result in a true conclusion, because the argument takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false.

b. It is the strongest property that is truth-preserving, in the sense that other means of deduction that also preserve truth do not allow for all of the derivations that this particular property allows.

Like what?!

Like, for example, deductions in the Aristotelian system. Being a deduction in that system is truth-preserving, but much weaker than the property of being valid.

In fact, as Bomb#20 already explained, this was progress over Aristotelian logic. You of course as usual ignored his point. Let me remind you:

There are clearly correct logical inferences that Aristotelian logic is too bloody weak to generate. "Daisy is one of my farm animals. All my livestock are cows or horses. All cows have hooves. All horses have hooves. Therefore, Daisy has hooves." Do that using Aristotle's syllogisms. It's trivial in predicate calculus.

Another weaker means of deduction is that given by intuitionistic logic. Now, intuitionistic logic agrees that a contradiction implies everything. However, as Bomb#20 already explained, intuitionistic logic does not accept ¬¬P->P. As a result, there are arguments that are not valid in intuitionistic logic even though they're valid by the usual definition. Now, all arguments that are valid in intuitionistic logic are also valid in classical logic (i.e., going by the definition I suggested), so in particular, the property of being valid with respect to intuitionistic logic is truth-preserving, but it is weaker, because there are derivations that intuitionistic logic does not allow (this might be an advantage in some contexts, but it does not change the fact that the strongest property of arguments that is truth-preserving is an important property in general, in truth-seeking contexts).

It can be used but it's no good. It works like crutches.

No, it works just fine. Look at the development of mathematics, physics, etc., using classical logic - and of course, it never leads from truth to falseness.

This is irrelevant. You're confusing logic with formal logic. Only formal logic is the preserve of whoever spends the time to learn it and then there are different methods of formal logic and we can all set up our own shop if we want. And you've now admitted there is no justification for the definition you use as the correct one, so, in effect you have to admit every shop is legitimate.

No, I'm not confusing anything. You are grossly misconstruing my words, and also attributing to me things I did not do or say.

And you should look up dictionaries more often, there are plenty of definitions of logic that don't assume it's only a technical term.

I never said "logic" is a technical term. I said that the meaning of "valid" relevant in this context is only captured by a very good dictionary that happens to be the very dictionary that you chose to give a definition of "valid" is a technical meaning. It captures also non-technical meanings of "valid", but those are neither the ones you quoted nor relevant in this context, since they are not about the validity of deductive arguments.

I also suggested that when lay people use the term "valid" referring to the validity of deductive arguments, they at least often yield to the experts for the definition; in other words, they are using the technical definition. Why do I think so? Well, if that were not so and there were an even more common usage, one would think any decent dictionary would pick it up.

Sometimes, I'd be a relief to be an idiot.

You are not an idiot. You are intelligent, but belief yourself to be far better at logic than you are.

 

[Speakpigeon]

No, that is an unreasonable assessment. Most mathematicians (for example) of course do not look for a justification of the definitions the terms they use. They just use the term. Some philosophers would give justifications, but the point is that I already gave a justification.

No you didn't.

I asked for a justification given by the professional experts themselves that the definition you use would be the correct one.

So again, it's reasonable to infer that you accept that there is no justification given by mathematicians, logicians, philosophers etc. that would support your claim that the definition of logical validity you use is the correct one.

I do not pretend. I do have expertise - not much, but not much is needed.

Yeah, sure, we all have not much expertise. Easy.

Not only is your answer false. It is absurd, and to a reader following the exchange rationally, it would be patently absurd. The property we are talking about is the property of arguments consisting in taking a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false. So, obviously, clearly, evidently, by the very definition, my claim that validity so defined preserves truth is true. As long as you have a form that is a valid argument, true premises result in a true conclusion, because the argument takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false.

You're assuming the conclusion that the definition you use is the correct one.

Like, for example, deductions in the Aristotelian system. Being a deduction in that system is truth-preserving, but much weaker than the property of being valid. In fact, as Bomb#20 already explained, this was progress over Aristotelian logic. You of course as usual ignored his point. Let me remind you:

There are clearly correct logical inferences that Aristotelian logic is too bloody weak to generate. "Daisy is one of my farm animals. All my livestock are cows or horses. All cows have hooves. All horses have hooves. Therefore, Daisy has hooves." Do that using Aristotle's syllogisms. It's trivial in predicate calculus.

Oh good, I was worried for a second.

No, it works just fine. Look at the development of mathematics, physics, etc., using classical logic - and of course, it never leads from truth to falseness.

It does.

I never said "logic" is a technical term. I said that the meaning of "valid" relevant in this context is only captured by a very good dictionary that happens to be the very dictionary that you chose to give a definition of "valid" is a technical meaning. It captures also non-technical meanings of "valid", but those are neither the ones you quoted nor relevant in this context, since they are not about the validity of deductive arguments.

No. You don't seem to understand my English too well. I have to repeat things again and again. This is a waste of time.

"Logic" and "valid" are not technical terms. "Validity" used in the context of logic is not a technical term. The dictionary I quoted first doesn't say "validity" is a technical term. You are making stuff up. You are an unreliable witness.

I also suggested that when lay people use the term "valid" referring to the validity of deductive arguments, they at least often yield to the experts for the definition; in other words, they are using the technical definition. Why do I think so? Well, if that were not so and there were an even more common usage, one would think any decent dictionary would pick it up.

That's what they do but your blinds work very good.

You are not an idiot. You are intelligent

You're just contradicting yourself.

According to your own post earlier, the "Dunning–Kruger effect is a cognitive bias in which people of low ability", so in effect, you have explicitly suggested I'm have low abilities. And now you're saying I'm intelligent.

You (...) belief yourself to be far better at logic than you are.

And how would you know how good I am at logic?! On the basis of a definition you can't justify?!

Talking of dogmatic people, you sure is one.
EB

 

[fast]

The particular definition in question is stipulative, and since it’s used by mainstream logicians, wanting to understand why it’s a superior definition is understandable. I say it lies with keeping the deductive argument separate and apart from its counterpart, the non deductive argument.