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I guess it comes down meaning of “sound”. Let me be more specific. An argument can correctly use the rules of logic and have an incorrect conclusion. This ca

by syops 6y ago

I guess it comes down meaning of “sound”. Let me be more specific. An argument can correctly use the rules of logic and have an incorrect conclusion. This can happen if some of the premises are false. For example: All men are immortal. Socrates is a man. Therefore Socrates is immortal. The rules of logic have been correctly followed but the conclusion is false.

tpoacher 6y ago
You mean valid. Not sound. By definition if an argument is sound, it is also valid (but not the reverse). And by definition if an argument is sound, then its conclusions are true. I think you're just mixing up the terminology a bit.
- syops 6y ago
  Well I did use logically sound and not sound argument. I personally don’t see a difference in logically sound and logically valid but I clarified things in my previous post.
  - MaxBarraclough 6y ago
    > I personally don’t see a difference in logically sound and logically valid They aren't the same. These are standard terms in logic, as explained in the Wikipedia article.
    - syops 6y ago
      Obviously I'm speaking in the vernacular and as I stated I used the terms as they meant to me. Besides logically sound and sound argument aren't the same thing in my mind. One refers to soundness of logic and the other to soundness of the argument. And that was the essence of my point. There's a difference in talking about an argument and talking about the logic used. Logical fallacies are only useful in determining if the reasoning was flawed. I didn't disagree with anything you wrote and even clarified my meaning so as to be clear. There is also the fact that, linguistically speaking, every person has a unique language. The meaning of words can vary slightly between people who nominally speak the same language. That's why I mentioned to me in my previous post. Clearly I was not writing in a mathematically precise way. I took mathematical logic in graduate school many years ago but am not qualified to use all of the terminology in a mathematically precise way. But this is an internet forum and not a course in mathematical logic. The standards of rigor are not so strict. Hence my phrase to me ought to have sufficed as far as clarification.
      - mannykannot 6y ago
        "I used the terms as they meant to me... every person has a unique language." Private languages are useless for communication, which depends on shared semantics. This thread is a clear example of that, as your first post here is very misleading except to anyone who a) knows that you are using your own private language, and b) actually knows what you mean by your words. In that post, using your own private definition of the various terms under discussion is worse than useless, as anyone who does not know what the accepted meanings are will end up worse off for reading it. “When I use a word,’ Humpty Dumpty said in rather a scornful tone, ‘it means just what I choose it to mean — neither more nor less.’ ’The question is,’ said Alice, ‘whether you can make words mean so many different things.’ ’The question is,’ said Humpty Dumpty, ‘which is to be master — that’s all.” ― Lewis Carroll, Through the Looking Glass
        syops 6y ago
        I agree I should have used "valid" when I used "sound". I also clarified what I meant by "logically sound". I further stated that I was using my parlance when I used "logically sound". What is interesting is that the responses to me have been about the meaning of sound argument and I never used this phrase. I used logically sound. Do you personally think logically sound and sound argument mean the same thing? I'm asking out of curiosity. EDIT: Private languages and the acknowledgement of them is not useless. It's a basis for being able to clarify things without a discussion devolving arguments over definitions of words. We all have slightly different ideas of what certain words mean.
        mannykannot 6y ago
        > I used logically sound. Do you personally think logically sound and sound argument mean the same thing? Well, the real point is that it is not clear what you mean here, and consequently what you are writing is likely to cause confusion and misunderstanding. In particular, as I pointed out in an earlier post, you were inconsistent in your own usage, sometimes using 'sound' correctly, and sometimes incorrectly. You also seem to think that because, in a series of follow-up posts, you can explain what you meant, then it follows that there was nothing wrong with your original post - but if no-one had replied to it, you would not have corrected it on your own, and it would have remained there, sowing confusion among those who did not know it was wrong (and, of course, being useless to those who do know it is wrong.) The size of the responses to your original post is a clear testament to the way private usage inhibits understanding and spreads confusion (though there would be considerably less if you had simply acknowledged your mistake immediately, and henceforward used 'sound' in its conventional sense.) > Private languages and the acknowledgement of them is not useless. I said that they are useless for communication (of course, they can be useful to the extent that they are not entirely private, but that caveat actually bolsters my point.) >It's a basis for being able to clarify things... Quite the opposite, as shown here: it's most often a basis for confusion and misunderstanding - and how could it not be? You have to achieve a shared meaning before there can be clarity and mutual understanding.
  - Veen 6y ago
    Sound and valid are terms of art in deductive logic. They have clearly defined meanings. Validity means the form of an argument is such that it's impossible for its premises to be true while the conclusion is false i.e. if the premises are true then the conclulsion must be true. Validity is a formal property of arguments and the relationships between premises. An argument can be valid even if its premises are false. Soundness means that an argument is valid and that the premises are true (and therefore the conclusion must be true). These are standard terms that have been used for over a century. You're going to generate a lot of confusion if you choose to use them differently to everyone who has ever studied elementary logic.
    - syops 6y ago
      Is there a difference in meaning between: sound argument logically sound I'm not aware of these phrases being the same. I took mathematical logic in graduate school many years ago and I've used logically sound to be something different than sound argument. I'm not disagreeing that valid would have been a better word choice. I did clarify my meaning in a subsequent post. I rewrote my point without using either sound or valid in an effort to be more precise.
      - mannykannot 6y ago
        See my reply here: https://news.ycombinator.com/edit?id=25971448 https://news.ycombinator.com/edit?id=25971448
mannykannot 6y ago
This is indeed an example of a valid but unsound argument (unsound because the first premise is false), and your use of 'sound' is correct here. Your first post, however, uses 'sound' in a manner that is inconsistent with both this example and correct usage. In particular, where you wrote "An argument can be logically sound but with a false conclusion" you presumably meant 'valid' instead of 'logically sound', as, by definition, sound arguments have true conclusions.
- syops 6y ago
  Hence my clarification where I stated the point differently. Yes, valid would have been a better choice. Do you see that you have taken my phrase logically sound and then switched to sound arguments? Do you think these mean the same thing?
  - mannykannot 6y ago
    This is a pedantically pointless argument. In the domain of logic, 'sound' has a very definite meaning, so what are we to make of your use of the word 'sound' in a discussion of logic, especially given that you explicitly qualify it with 'logical'? What is the point of phrasing a statement in such a way that it will mislead everyone except those who can see what you actually meant? Those people already know what you are trying to say. I have not "taken [your] phrase logically sound and then switched to sound arguments". What I did, in the clause "sound arguments have true conclusions", was to make a statement of fact about the meaning of the word 'sound' in the domain of logic. On account of that being so, it would have been unequivocally wrong for you to have written "An argument can be sound but with a false conclusion." Ah, but you say (this is where it gets really pedantic) you did not write precisely that; you wrote "An argument can be logically sound but with a false conclusion" - but how do you think the modifier logically will be taken here, given that 'sound' has a specific meaning in the domain of logic? Don't tell us that (obviously!) 'logically sound' actually means 'valid'!
    - xupybd 6y ago
      Communication is hard. It's harder when both parties are not using the same definitions. I've found this is one of the biggest difficulties in hashing out an argument with a stranger online. With someone I know I can spot when our definitions don't match. Online it takes a lot more back and forth and often is less friendly.
deleted 6y ago
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by syops 6y ago

tpoacher 6y ago

You mean valid. Not sound. By definition if an argument is sound, it is also valid (but not the reverse). And by definition if an argument is sound, then its conclusions are true. I think you're just mixing up the terminology a bit.

syops 6y ago
Well I did use logically sound and not sound argument. I personally don’t see a difference in logically sound and logically valid but I clarified things in my previous post.
- MaxBarraclough 6y ago
  > I personally don’t see a difference in logically sound and logically valid They aren't the same. These are standard terms in logic, as explained in the Wikipedia article.
  - syops 6y ago
    Obviously I'm speaking in the vernacular and as I stated I used the terms as they meant to me. Besides logically sound and sound argument aren't the same thing in my mind. One refers to soundness of logic and the other to soundness of the argument. And that was the essence of my point. There's a difference in talking about an argument and talking about the logic used. Logical fallacies are only useful in determining if the reasoning was flawed. I didn't disagree with anything you wrote and even clarified my meaning so as to be clear. There is also the fact that, linguistically speaking, every person has a unique language. The meaning of words can vary slightly between people who nominally speak the same language. That's why I mentioned to me in my previous post. Clearly I was not writing in a mathematically precise way. I took mathematical logic in graduate school many years ago but am not qualified to use all of the terminology in a mathematically precise way. But this is an internet forum and not a course in mathematical logic. The standards of rigor are not so strict. Hence my phrase to me ought to have sufficed as far as clarification.
    - mannykannot 6y ago
      "I used the terms as they meant to me... every person has a unique language." Private languages are useless for communication, which depends on shared semantics. This thread is a clear example of that, as your first post here is very misleading except to anyone who a) knows that you are using your own private language, and b) actually knows what you mean by your words. In that post, using your own private definition of the various terms under discussion is worse than useless, as anyone who does not know what the accepted meanings are will end up worse off for reading it. “When I use a word,’ Humpty Dumpty said in rather a scornful tone, ‘it means just what I choose it to mean — neither more nor less.’ ’The question is,’ said Alice, ‘whether you can make words mean so many different things.’ ’The question is,’ said Humpty Dumpty, ‘which is to be master — that’s all.” ― Lewis Carroll, Through the Looking Glass
      - syops 6y ago
        I agree I should have used "valid" when I used "sound". I also clarified what I meant by "logically sound". I further stated that I was using my parlance when I used "logically sound". What is interesting is that the responses to me have been about the meaning of sound argument and I never used this phrase. I used logically sound. Do you personally think logically sound and sound argument mean the same thing? I'm asking out of curiosity. EDIT: Private languages and the acknowledgement of them is not useless. It's a basis for being able to clarify things without a discussion devolving arguments over definitions of words. We all have slightly different ideas of what certain words mean.
        mannykannot 6y ago
        > I used logically sound. Do you personally think logically sound and sound argument mean the same thing? Well, the real point is that it is not clear what you mean here, and consequently what you are writing is likely to cause confusion and misunderstanding. In particular, as I pointed out in an earlier post, you were inconsistent in your own usage, sometimes using 'sound' correctly, and sometimes incorrectly. You also seem to think that because, in a series of follow-up posts, you can explain what you meant, then it follows that there was nothing wrong with your original post - but if no-one had replied to it, you would not have corrected it on your own, and it would have remained there, sowing confusion among those who did not know it was wrong (and, of course, being useless to those who do know it is wrong.) The size of the responses to your original post is a clear testament to the way private usage inhibits understanding and spreads confusion (though there would be considerably less if you had simply acknowledged your mistake immediately, and henceforward used 'sound' in its conventional sense.) > Private languages and the acknowledgement of them is not useless. I said that they are useless for communication (of course, they can be useful to the extent that they are not entirely private, but that caveat actually bolsters my point.) >It's a basis for being able to clarify things... Quite the opposite, as shown here: it's most often a basis for confusion and misunderstanding - and how could it not be? You have to achieve a shared meaning before there can be clarity and mutual understanding.
- Veen 6y ago
  Sound and valid are terms of art in deductive logic. They have clearly defined meanings. Validity means the form of an argument is such that it's impossible for its premises to be true while the conclusion is false i.e. if the premises are true then the conclulsion must be true. Validity is a formal property of arguments and the relationships between premises. An argument can be valid even if its premises are false. Soundness means that an argument is valid and that the premises are true (and therefore the conclusion must be true). These are standard terms that have been used for over a century. You're going to generate a lot of confusion if you choose to use them differently to everyone who has ever studied elementary logic.
  - syops 6y ago
    Is there a difference in meaning between: sound argument logically sound I'm not aware of these phrases being the same. I took mathematical logic in graduate school many years ago and I've used logically sound to be something different than sound argument. I'm not disagreeing that valid would have been a better word choice. I did clarify my meaning in a subsequent post. I rewrote my point without using either sound or valid in an effort to be more precise.
    - mannykannot 6y ago
      See my reply here: https://news.ycombinator.com/edit?id=25971448 https://news.ycombinator.com/edit?id=25971448

mannykannot 6y ago

This is indeed an example of a valid but unsound argument (unsound because the first premise is false), and your use of 'sound' is correct here. Your first post, however, uses 'sound' in a manner that is inconsistent with both this example and correct usage. In particular, where you wrote "An argument can be logically sound but with a false conclusion" you presumably meant 'valid' instead of 'logically sound', as, by definition, sound arguments have true conclusions.

syops 6y ago
Hence my clarification where I stated the point differently. Yes, valid would have been a better choice. Do you see that you have taken my phrase logically sound and then switched to sound arguments? Do you think these mean the same thing?
- mannykannot 6y ago
  This is a pedantically pointless argument. In the domain of logic, 'sound' has a very definite meaning, so what are we to make of your use of the word 'sound' in a discussion of logic, especially given that you explicitly qualify it with 'logical'? What is the point of phrasing a statement in such a way that it will mislead everyone except those who can see what you actually meant? Those people already know what you are trying to say. I have not "taken [your] phrase logically sound and then switched to sound arguments". What I did, in the clause "sound arguments have true conclusions", was to make a statement of fact about the meaning of the word 'sound' in the domain of logic. On account of that being so, it would have been unequivocally wrong for you to have written "An argument can be sound but with a false conclusion." Ah, but you say (this is where it gets really pedantic) you did not write precisely that; you wrote "An argument can be logically sound but with a false conclusion" - but how do you think the modifier logically will be taken here, given that 'sound' has a specific meaning in the domain of logic? Don't tell us that (obviously!) 'logically sound' actually means 'valid'!
  - xupybd 6y ago
    Communication is hard. It's harder when both parties are not using the same definitions. I've found this is one of the biggest difficulties in hashing out an argument with a stranger online. With someone I know I can spot when our definitions don't match. Online it takes a lot more back and forth and often is less friendly.

deleted 6y ago

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