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C. S. Lewis, or whatever it is that I'm in the mood to discuss.

Monday, June 22, 2009

Popular and logical validity

•Validity is a huge concept. It is the centerpiece of discussion when it comes to all deductive arguments.•An argument is valid just in case the argument is structured in such a way that if the premises are true, then the conclusion must also be true. To put it another way, if the premises are true, there is no possible way that the conclusion can be false.

•Popular validity and logical validity•Mind you that the definition I provided above is not the popular concept of validity. We sometimes just use the term “valid” as a word for legitimate. So, for example, we would not say that telling the teacher that the dog ate your homework is a valid excuse. (A goat maybe, not a dog). Nevertheless, that excuse can be made into a valid argument.

Let’s take this argument:•If I say my dog ate my homework, then I have a valid excuse.•I say that my dog ate my homework.•Therefore, I have a valid excuse.This is a valid argument, according to the logical definition of “valid” because if the premises are true, the conclusion must be true. Most of us would agree that the conclusion is false. But that is because we are inclined to reject the first premise. If the first premise were true, and the second also, then the conclusion would have to be true. The argument is valid (logical sense) even though the excuse is not (popular sense).

For instance, if one presumed "libertarian freewill," how would one confirm that one has libetarian freewill? Or disconfirm it? Can someone please come up with an experiment that can be performed?

Does "libertarian freewill" even make perfect logical sense? If one can choose something completely different if the circumstances and time were run back to point zero (including time) and you were actually given a second choice with all other factors being absolutely equal, then what would such a "choice" amount to? You make one choice the first time the experiment is run (not that such an experiment could ever BE run since we can't return to point zero in time and space and in our own bodies and minds, can we?), and then the second time the experiment is run you make a different choice? What exactly happened? What did the choosing each time, and why, based on what? Would you thereby have proven that we each have the power to make baseless choices lying outside the whole time-space continuum? What good would such an ability be? One might as well have simply spun a wheel of fortune if you wanted to make unpredictable "choices."

Or does it make more logical sense and add validity to ones choices if you want to live in a cosmos where your choices are based on the sum total of everything you've known and experienced up till that point, even though such choices will never be but ONE CHOICE each time?

I'd rather the second case be true rather than "libertarian freewill," thank you very much. I'd rather be connected with the cosmos and my choices be based on my accumulated knowledge and learning (though sometimes I would also admit that I forget things, or my choices may sometimes be driven by more immediate impulses rather than thinking out the long range effects of each choice, so I would never be a perfect choosing machine). But doesn't that make my choices still more valid than the libertarian dream that it's possible to "make any choice" if you just run things back to point zero enough times? Instead, connect me with the cosmos, please!

On validity, it also depends what one is attempting to verify, and experiences differ.

In my case I have never experienced what one might call a full blown miracle.

I've experienced joy while praising God, but the experience seemed self-induced since I experienced different levels over time and in different circumstances.

I've experienced coincidences, before entering the fold, while in the fold, after leaving the fold.

But I've never seen anyone healed, like a bone broken all the way througn on an x-ray one day and healed the next day, or like an eye regrow in a socket, a severed limb regrow, seen someone raised from the dead, heard God's voice, heard any voice, or had any visions of people, nor seen any ghostly apparitions.

That seems to validate for me at least that I'm just not as "lucky" as people who believe miracles are happening all the time.

I also don't live in a time and place in history where the most intelligent members of society place a whole lot of stock in miracles (though some highly intelligent people do, usually those people are also members of religions that rely on such miracles as told in their ancient holy books, i.e., in support of said religion).

So I am "stuck" having to make decisions based on my own life experiences, though even there, I am open to miracles, just haven't experienced any myself, and so I live each day based on the sum total of my experiences and knowledge and try to make wise decisions based on what I've learned and via looking ahead at possible consequences, though I cannot predict in any absolute fashion how each decision will end up. So I live with uncertainties and admitted blind spots as to other people's reactions, and as to my own future. I don't live by relying on prayers and miracles and religious rituals and putting on a pedestal a singular holy book, but try to seek what's best in all people and books. That's life and valid enough for me, the inexpressible instant of each living moment, the joys and the uncertainties.

So I am "stuck" having to make decisions based on my own life experiences, though even there, I am open to miracles, just haven't experienced any myself, and so I live each day based on the sum total of my experiences and knowledge

The 'popular' sense of validity is found in some systematic approaches to reasoning as well; for instance, in discussions of construct validity in case study research, which deals (roughly) with the appropriateness of one's measurements and classifications to the actual features of the case being studied.

Reppert: """•An argument is valid just in case the argument is structured in such a way that if the premises are true, then the conclusion must also be true. To put it another way, if the premises are true, there is no possible way that the conclusion can be false.""""

Close, but arguments can be valid, even with only probable, spurious (think Lewis Carroll), or even false premises. Arguments which are sound require true premises, AND a valid conclusion (which is to say a valid form, such as modus ponens).

Consider:

""""If an organism has wings, it can fly.

Ostriches have wings.

Therefore Ostriches fly."""

Completely valid, but not sound (first premise not true).

Doc Reppert sort of missed out on soundness. Fairly common oversight, even among "filosophes".

Close, but arguments can be valid, even with only probable, spurious (think Lewis Carroll), or even false premises. Arguments which are sound require true premises, AND a valid conclusion (which is to say a valid form, such as modus ponens).

Dr. Reppart has discussed soundness before. I don't think it should be necessary to mention the concept of soundness in every discussion of logical validity. Your addition of the item of soundness made the discussion no "close"r than it already was.

You ASSUME that logical outcomes in the brain/mind are inconsistent with a cosmos made up purely of matter and energy and their regular interactions.

But you don't know what matter/energy are capable or incapable of, and you certainly cannot VALIDLY compare organized cells and specialized organs of cognition and specialized sensory organs with processes on a sub-atomic level. The organization of atoms into molecules and then into cells and organs, and the intake of information in the world around each human brain/mind, being taken in IN A MASSIVE WHOLESALE FASHION, and then compared in a MASSIVE WHOLESALE FASHION is what thinking and logic and reasoning is all about, and that does NOT appear to be logically incompatible with a cosmos made up purely of matter and energy.

So your argument proves nothing EXCEPT what you aimed it to prove via unproven premises in the beginning.

I was attempting to explicate the conception of validity in logic, and compare that conception to certain popular ideas. I took a piece out of a class powerpoint I was prepring, if you must know. So that was the idea that I was trying to explain. Soundness is another concept that we might also want to understand, but I wasn't talking about that. What I was talking about was the difference between the concept of validity that we might use in ordinary language "that was a valid excuse for not bringing in my homework today" and "the Socrates syllogism is a valid argument form."

O-B: No one claimed otherwise. That you think I erred in this regard somehow is an indication that you did not comprehend my post.

You didn't claim anything, O-b (holy acronym, batman). Like the rest of the DI geniuses, you didn't note that Dr. Reppert was in fact discussing soundness AND validity, until I pointed it out, and then the usual........quite right.

It's a bit amusing to hear sunday schoolers defend logic, either Aristotelian or modern propositional sort--neither of which had anything to do with the history of ju-christian monotheism (or, shall we say, monotheism had nothing to do with Logic).

The thomistic sorts did admittedly pick up on Aristotle (some might say misconstrue), but I don't think there are any altar boys around. What did Luther say? Reason is a whore or something. Same mostly for the Calvin corps. I suspect the old bapticks and prezbyterians arrested heathens for even mentioning Aristotelian syllogisms.

"Doc Reppert sort of missed out on soundness. Fairly common oversight, even among "filosophes"."

This post wasn't at all about soundness. It was about formal validity vs the popular conception of validity. No one was denying that soundness was important. Sorry, but I have to agree with One-brow on this one. You totally missed the ball on this one, and quite unnecessarily for such a simple point.

Logical validity is independent of truth--the truth relates to premises. Sound arguments have true premises AND valid form (and it's the form which lends it validity, not the status of premises). So Reppert is not correct, except in informal sense (ie popular).

If crows fly, so do preachers.

Crows fly.

Preachers fly!

Perfectly valid, but unsound. When you say, that's wrong, you're merely saying the first premise is false.

J, you are one daft dude. You're just confused. What you're talking about is the premises themselves possibly being false in reality and yet the argument still remaining valid. No doubt Reppert would accept that. What he's clearly saying is that if you were to hypothetically suppose the premises as true then the conclusion must also be true in a valid argument form. And he's correct here. Therefore, truth in this sense is a NECESSARY part of validity, contrary to what you said. In fact, pretty much all logic textbooks define validity with reference to truth. Let me provide you with one:

"An argument is valid if and only if it's impossible for all of the premises of the argument to be true and the conclusion false."("Introduction to Logic and Critical Thinking"; Merrilee H. Salmon)

That is a formal definition of validity found in a logic textbook so Reppert did no wrong defining it in this manner. Moreover, he is the philosophy professor here, not you. To think that Reppert actually doesn't know what he's talking about here would be utterly amazing. Please stop yapping on about nothing. You have no point and you're wasting time and virtual ink on something you already lost from the start.

No kidding, dewd--some of us, like not from midwest or AZ also aced a discrete math course! wowee . That's not the quote anyway. Let me reiterate, Jay Dafty:

Reppert: """•An argument is valid just in case the argument is structured in such a way that if the premises are true, then the conclusion must also be true. To put it another way, if the premises are true, there is no possible way that the conclusion can be false.""""

To say "just in case" seems to imply that the premises must be true to have valid conclusion, and that AIN'T correct. Look it up in Bergman, or Copi, Quine, or Schmendrickstein. One can have a valid argument without true premises. It's unsound, but valid. And that's logic.

I understand what Mr Reppert was doing, and it might work for intro. course, but I do think it's imprecise and rather sloppy (especially for pro.).

No hard feelin's VR. Or Jay Dafty (now, reread a few times until you get it).

DI="Downright Intimidating"? I cant think of any other DI that would apply to me.

you didn't note that Dr. Reppert was in fact discussing soundness AND validity, until I pointed it out, and then the usual........quite right.

Except, he did not mention soundness, which is a different concept than what he means by popular validity, from what I can see.

It's a bit amusing to hear sunday schoolers defend logic, either Aristotelian or modern propositional sort--neither of which had anything to do with the history of ju-christian monotheism (or, shall we say, monotheism had nothing to do with Logic).

That rather depends upon which aspect of monotheism you are discussing,I should think.

Not that it matters. Being logically valid is the argumentative equivalent of doing a swan dive in competition.

You're mistaken re Ilion as well, O-B. Unlike Il Duce Idion, Mussolini of Online Morali-tay, I value logic, evidentiary argument and shall we say, Jeffersonian democracy instead of dogma and religious hysteria (I might make use of satire, but he routinely resorts to defamation and insults). He sounds like Curtis Silwa on crack. Or is it David Duke.

I am SO sorry! You see, poor, willfully-deluded One Brow, having long ago concluded that you are simply the "nice" version of Perezoso/J, I so rarely even look at your posts. I've been gently teasing you about having encountered yourself, and I missed this ---

Ilíon: "Computation -- which is merely counting (*)-- is not thought. Furthermore, the mere mechanical movement of bits of matter from here to there is not even counting."

[(*) I might have said "counting and comparing," but even simple, straight-forward counting contains a comparison step.]

One Brow: "When you can demonstrate a qualitative difference, your statement will be more than bare assertion."

Come now! You *know* that I'm not a member of the Church of Niceanity. You *know* that I refuse to play the "Let's all pretend that we ought to take seriously the stupid (or, if not stupid, then intellectually dishonest) things which 'atheists' say for the purpose of protecting atheism. YAY!" game.

The burden of proof is on you, you willfully self-blinded fool. But, as it's impossible to prove falseness to be true, even fools such as you know that your only recourse is to attempt an invalid shifting of the burden of proof. But I am not "nice," and I decline to take your burden.

Computation is not thought: No computer software, no matter the computer hardware on which it runs, will ever he a mind. This is reality; deal with it!

Furthermore, if you assert the falseness that computation (counting) is equivalent to mind, then reason and honesty (big stretch for you on both, I know) requires you to at least concede that you yourself are just a computer program.

And, since you hold yourself to be merely a computer program, reason and (in my case personal) knowledge of the workings of computer programs leads us to the further knowledge that you hold yourself (non-exhaustively and in no particular order):* unable to think* unable to grasp truth* unable to learn* unable to know* unable to reason* unable to choose* unable to love* unable to be lovedIn short, you hold yourself to have none of the characeristics of minds-as-we-each-experience-them to be. The computer-which-is-you might as well be made of macaroni, for all the difference instantiation makes.

Ilíon: "Minds are capable of treating the mere mechanical movement of bits of matter from here to there as though it were counting -- minds can make and use symbols; symbols do not make minds."

One Brow: "Which does nothing to show that, fundamentally, minds have physical sustance that goes beyond on/off switches."

And you're an intellectually dishonest fool (which statement is, of course, a redundancy).

Minds are not conglomerations of matter: this is reality; deal with it!

You're still wrong, and you still seem to have trouble with the spelling of my name. It's only 7 letters. It's hard to take you seriously then you continually fail even after correction.

Try Guru Wiki on Validity, ...

That description matches what Dr. Reppert said. That you think otherwise is an indication of some sort of misinterpretaion or malfunction.

You're mistaken re Ilion as well, O-B.

Perhaps, but I doubt I am mistaken in any fashion you can present with both accuracy and inteligibility, given your past behavior in this thread. If you think Ilion does not value logic, you gravely misunderstand both Ilion and logic.

In fact, you sound nearly biblethumper-like in your inability to understand the issue. Validity is mere tautology. Soundness on the other hand relates to truth, proof, verification (and some, even Wittgenstein apparently would not permit inductive/empirical statements used in formal logic). Then the typical accountant-programmer often mistakes his Quicken program or template du jour for the world.

I actually like the taste of my own medicine. You so far have simply not given to me, nor had J.

Come now! You *know* that I'm not a member of the Church of Niceanity. You *know* that I refuse to play the "Let's all pretend that we ought to take seriously the stupid (or, if not stupid, then intellectually dishonest) things which 'atheists' say for the purpose of protecting atheism. YAY!" game.

Actually, I don't really see that as being relevant. Some of the most nastiest posters I have come across were nonetheless quite capable of distinguishing between their assertions and their evidenced position, some were not. Frankly, in the nice-nasty continuum, you fall well into the middle anyhow.

The burden of proof is on you, you willfully self-blinded fool.

If I were to make a positive claim that minds were definitely an emergent property of brains, I should certainly offer proof thereof. At this point, I would say it is my expectation this is true based on certain indications, but I could also be wrong, and I have no definitive statements to offer.

But, as it's impossible to prove falseness to be true, even fools such as you know that your only recourse is to attempt an invalid shifting of the burden of proof.

A definitive statement encumbers a burden of proof. This is true whether the statements posits a mind emerging from the brain or a mind as a separate entitiy connected to the brain.

Further evidence-free assertions removed, as repeating an assertion does not make it more true or more evidenced.

Furthermore, if you assert the falseness that computation (counting) is equivalent to mind, then reason and honesty (big stretch for you on both, I know) requires you to at least concede that you yourself are just a computer program..

If you take my biological body to be the computer, than yes, I actually do believe my consciousness, wants, expectations, emotions, commitments, etc. are all the expressions of some very sophistocated programming that has emerged through a gradual process.

... reason and (in my case personal) knowledge of the workings of computer programs leads us to the further knowledge that you hold yourself ... In short, you hold yourself to have none of the characeristics of minds-as-we-each-experience-them to be. .

I was unaware we had reach the limits of what computers could emulate, or had positive proof that our experiences were of a qualitative difference. In fact, I hold that it will eventually be possible to create computers that experience many of these same characteristics.

The computer-which-is-you might as well be made of macaroni, for all the difference instantiation makes..

Based on my diet, a considerable protion of it is made of oatmeal and eggs.

I find it increasingly unlikely that, should I ever be incorrect in the future, I would be able to credit you perception on this, given your repition of points both irrelevant and conceded, continued insistence that you, and not the 3-4 other people you have discussed this with -- including the author of the post, have correctly interpreted the original post, and you inability to spell a name of seven simple letters.

In fact, you sound nearly biblethumper-like in your inability to understand the issue.

In fact, your opinion on this issue has no meaning to me.

Validity is mere tautology.

This is close to accurate. Symbolocially every valid proof can be converted into a tautology. However, they are not tautologies per se.

Soundness on the other hand ...

Was not addressed at all in the original post, and is irrelevant to a discussion of it.

Now, if you really feel I'm wrong, make an argument that shows Dr. reppert addressed soundness in the original post, if you can.

O-B, you're not the judge or teacher here. I don't care for you either. You don't respond to the points. You don't understand validity or soundness (validity IS merely a tautology, not really even about truth). I don't think you get Goedel, or even the difference between deduction and induction. And you're not funny either.

I have a hard time believing that you aced a discrete math class, much less any class J.

"To say "just in case" seems to imply that the premises must be true to have valid conclusion, and that AIN'T correct."

Not really, that's why Reppert said the conditional "if" for the premises being true. That's clearly supposing the hypothetical here and not that the premises need be true in reality.

"Look it up in Bergman, or Copi, Quine, or Schmendrickstein. One can have a valid argument without true premises. It's unsound, but valid. And that's logic."

We know that already. No one denied that. Again, you're just confused about what Reppert said and how definitions of validity are usually defined.

"I understand what Mr Reppert was doing, and it might work for intro. course, but I do think it's imprecise and rather sloppy (especially for pro.)."

Well apparently you don't understand what he was actually doing since you accused him of trying to put forward the incredible suggestion that validity is only for arguments with actually true premises. To think that Reppert doesn't know that premises of an argument can be false while still remaining valid is again incredible. It's obvious that he knows this. Why else would he object to arguments against the AFR that he admits are valid but contain false premises?What he stated in the initial post was correct.

I gave you a formal definition of validity from a logic textbook which is virtually identical with what Reppert said in the OP so at the end of the day you don't have a point. I suggest you re-read it and maybe it will sink in.

"And since you want to be a tough guy, maybe step in a ring, like legal, LA area, and Ill show you some more about logic, Jayski"

What a whiny baby you are. Seriously, the fact that you get all upset over a comment on a blog and feel the need to invite physical harm on me just shows how pathetic you are, not to mention reinforces how stupid I thought you were.

"Yr not logician."

Do I need to be a logician to show what a correct definition of validity is to you?.... That's what I thought. Apparently though, I did need to provide you with a formal definition of the word from a logic textbook. Let me provide it to you again, ok pumpkin:

"An argument is valid if and only if it's impossible for all of the premises of the argument to be true and the conclusion false."

Feel free to re-read it if necessary.

"Just another bible thumper."

Yeah about that. I'm actually an agnostic, and an agnostic that thinks you're an idiot. LOL, I bet you didn't see that one coming.

J, you are wrong. What Victor said is fine. It's like the site is infected with two Ilions, one an antisemite on PCP, the other just unable to confront arguments head on without using the word 'dishonest.'

Sorry to see it went this route Victor. I'll check back in a few months.

BDK: "... It's like the site is infected with two Ilions, one an antisemite on PCP, the other just unable to confront arguments head on without using the word 'dishonest.'"

On the other hand, and as we all understand, I use 'dishonest' when it's appropriate, not indiscriminately.

The truth is that Peresozo behaves the way that you falsely assert that I do ... and, the discerning eye will over time notice that Peresozo's behavior is a heightened or distilled version of your own behavior.

Here is an amusing trip down memory lane:

Anonymous: "What's really hilarious is BDK dismissing Ilion for his tone - to, of all people, Perry the wannabe philosopher who spouts off as much or more trash than Ilion ever does, and far more often.

At least Ilion tends to make sense. Perry's all bluster, and BDK.. you have a veneer of politeness, but it's just a veneer over very little substance. But at least you've got the veneer. Learn something from the man, Perry!"

BDK: "Anonymous: I try to be honest, not polite. There is a huge difference. At this site it is sometimes tempting to tone down my naturalism to make it seem more friendly to theists, but that would be dishonest, as it is inconsistent with theism."

One Brow: "If I were to make a positive claim that minds were definitely an emergent property of brains, I should certainly offer proof thereof. At this point, I would say it is my expectation this is true based on certain indications, but I could also be wrong, and I have no definitive statements to offer."

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About Me

I am the author of C. S. Lewis's Dangerous Idea: In Defense of the Argument from Reason, published by Inter-Varsity Press. I received a Ph.D in philosophy from the University of Illinois at Urbana-Champaign in 1989.