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Quine- Synonmym- Interchangibility

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Quine- Synonmym- Interchangibility
DaveStillLearning
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Posted 05/22/09 - 08:39 AM:
Subject: Quine- Synonymy- Interchangibility
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#1
Hello,

Maybe somebody can help me with this. Reading Quine's 'Two Dogmas of Empiricism', when discussing interchangeability of synonyms he says that in a hypothetical extensional language where synonyms are interchangeable by virtue of having the same truth value..what is meant my 'truth value'? He says that two words could be interchanged preserving truth-value but not meaning. How does 'creature with a heart' and 'creature with a kidney' have the same truth value? He goes on to say that the modal adverb 'necessarily' is required to fix the problem thereby presupposing necessity and analytical, but I can't understand this until I understand the former idea.

Any help is appreciated.

Edited by DaveStillLearning on 05/22/09 - 09:04 AM
DaveStillLearning
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Posted 05/22/09 - 08:58 AM:
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Is it, perhaps:

'All x's are unmarried' -true
'All x's are bachelors' -true

'All x's have a heart' -true
'All x's have a kidney' -true

the former can be interchanged preserving meaning and truth value, but the latter, if interchanged, do not have the same meaning. so the former may accidentally work, but not the latter?
makerowner
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Posted 05/22/09 - 11:47 AM:
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The two predicates "is a creature with a heart" and "is a creature with a kidney" have the same extension, so any true sentence that contains one of those predicates would remain true if the other one were substituted in. Any two sentences that differ only in which of these two predicates they contain will have the same truth-value; ie. they must both be true or both false. Quine's point is that there doesn't seem to be a clear way of distinguishing this kind of interchangeability that we would like to call a fact about the world (it doesn't seem in any way necessary that hearts should always be accompanied by kidneys; it's just that kidneys and hearts always happen to be found together), from the kind of interchangeability we would like to call a fact about language (eg. "all bachelors are unmarried"). Any attempt to single out the latter kind as 'analytic' involves recourse to concepts like 'meaning' or 'necessity' that are part of what's in question.

For philosophy, Socrates, if pursued in moderation and at the proper age, is an elegant accomplishment, but too much philosophy is the ruin of human life. Even if a man has good parts, still, if he carries philosophy into later life, he is necessarily ignorant of all those things which a gentleman and a person of honour ought to know.
DaveStillLearning
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Posted 05/22/09 - 05:19 PM:
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Forgive me, but, 'have the same extension'. Do you refer to the form here, as in structural form - 'is a creature with an x'. Surely not.
makerowner
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Posted 05/22/09 - 08:02 PM:
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DaveStillLearning wrote:
Forgive me, but, 'have the same extension'. Do you refer to the form here, as in structural form - 'is a creature with an x'. Surely not.


The set of creatures with kidneys coincides with the set of creatures with hearts. Or, if x is a creature with a heart, then x is a creature with a kidney, and vice versa. Or, there is no creature with a heart and no kidney, or vice versa. See en.wikipedia.org/wiki/Extension_(semantics)

For philosophy, Socrates, if pursued in moderation and at the proper age, is an elegant accomplishment, but too much philosophy is the ruin of human life. Even if a man has good parts, still, if he carries philosophy into later life, he is necessarily ignorant of all those things which a gentleman and a person of honour ought to know.
Philo1965
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Posted 06/18/09 - 06:19 PM:
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makerowner wrote:
The two predicates "is a creature with a heart" and "is a creature with a kidney" have the same extension, so any true sentence that contains one of those predicates would remain true if the other one were substituted in. Any two sentences that differ only in which of these two predicates they contain will have the same truth-value; ie. they must both be true or both false.


Except, of course, in intensional contexts.
aufbau87
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Posted 06/25/09 - 09:34 PM:
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DaveStillLearning wrote:
Hello,

Maybe somebody can help me with this. Reading Quine's 'Two Dogmas of Empiricism', when discussing interchangeability of synonyms he says that in a hypothetical extensional language where synonyms are interchangeable by virtue of having the same truth value..what is meant my 'truth value'? He says that two words could be interchanged preserving truth-value but not meaning. How does 'creature with a heart' and 'creature with a kidney' have the same truth value? He goes on to say that the modal adverb 'necessarily' is required to fix the problem thereby presupposing necessity and analytical, but I can't understand this until I understand the former idea.

Any help is appreciated.


The truth values are True or False. 'Michael Jackson died on June 25' and 'All dogs are animals' have the same truth value, namely, True.

Notice, though, that True and False are values of sentences, not singular or general terms (sentence fragments, if you will). So 'creature with a heart' and 'creature with a kidney' do not have the same truth-values -- indeed, it is not permissible to assign them ANY truth-value. Only sentences have truth-values.

Quine's point is this: suppose someone told you "I have a criterion of synonymy: two terms are synonymous if and only if they are interchangeable salva veritate".

What does "interchangeable salva veritate" mean? Two terms are interchangeable salva veritate if and only if they can replace each other in the sentences where any of them occur without changing the truth-value of the sentences. A variant formulation might be that two terms are interchangeable salva veritate if and only if what is true of one term is true of the other.

The good news, as Quine might concede, is that "bachelor" and "unmarried male" are interchangeable salva veritate; what's true of our bachelors is true of our unmarried males; that is to say, the terms can be freely substituted for one another in sentences without changing their truth-values. If 'Dan is a bachelor' is true, then 'Dan is an unmarried male' is, as well; if 'All bachelors are rowdy' is false, then so is 'All unmarried males are rowdy' is false, as well.

So far, so good. We think the two terms are synonymous (are alike in meaning) and they satisfy the condition of being interchangeable salva veritate.

Quine's point about the 'creature with a heart' and 'creature with a kidney' is that the two terms are interchangeable salva veritate, YET, we'd suppose that the two general terms have different meanings (i.e., they are not synonymous).

Of course, one will come back and say "Yes, but it is by accident that the two general terms 'creature with a heart' and 'creature with a kidney' are interchangeable salva veritate. In contrast, 'bachelor' and 'unmarried male' are NECESSARILY interchangeable salva veritate!"

Quine's next course is to knock this down (Benson Mates' view, I think) in virtue of the fact it relies on the notion of necessity which is in just as much in need of clarification as is 'synonymous' and 'analytic'.

NOTE: To say two terms are interchangeable salva veritate implies they have the same extension. 'bachelor' and 'unmarried male' are general terms true of myself and others (the enumeration of the objects is the extension).
yasseford
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Posted 07/10/09 - 09:47 AM:
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aufbau87 wrote:

Notice, though, that True and False are values of sentences, not singular or general terms (sentence fragments, if you will). So 'creature with a heart' and 'creature with a kidney' do not have the same truth-values -- indeed, it is not permissible to assign them ANY truth-value. Only sentences have truth-values.



Consider the sentence: "The present King of England is named George." Russellian translation: There is an x and only one x such that x is the present King of England and x is named George. This sentence is true at different points in history, and presently is false. Can we say that sentences themselves have truth-values? To me, it would seem more accurate to say that assertions of sentences have truth-values, and assertions arise from the usage of the sentence.

Yasseford
aufbau87
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Posted 07/10/09 - 11:53 AM:
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Quine makes a distinction between "occasion" sentences and "eternal" sentences. Basically, the former sentences are sometimes true, sometimes false, usually due to words such as "I", "now", etc. Eternal sentences are tenseless. "Jeff goes to the store" is an occasion sentence; to make it able to be couched in first-order predicate logic (with identity) proper, we render the sentence "eternal", true or false (and not both) once and for all: "Jeff goes to the store July 10th, 2009 at 4:06pm". The specifications will go on as we need them to.

The sentence "The present King of England is named George" is likewise rendered "eternal" by substituting specifications for the word "present", e.g.:

"The King of England in [whatever specific time in history] is [tenseless] named George". Construed this way, the sentence is no longer true on some occasions, false on others.

I tend to agree with your view on assertions and sentences, but this above is what Quine would likely say in return to your challenge.
yasseford
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Posted 07/13/09 - 06:03 AM:
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It seems counter-intuitive to create the eternal/occasion distinction when Quine admits that meaning is not inherently attached to a word. I'm a sophist when it comes to Quine's philosophy of language though, so perhaps there is some merit to having this sort of distinction that is beyond me.

Yasseford
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