But I think that it is possible in certain circumstances that P and not "P" is true. — Sapientia

What circumstances would that be? Remember that philosophers who employ the disquotational schema (e.g. Tarskian truth theorists, disquotationalists, deflationists, minimalists, identity truth theorists, or prosentential truth theorists) all are using it in contexts where it is assumed that the truth conditions of the mentioned sentence are determined by means of the used sentence (on the right hand side of the biconditional). Hence, circumstances where its truth conditions would be different from the truth conditions of the used sentence are ruled out. So, it's rather like I were saying that if a natural number N is smaller than 3 then,

N is prime if and only if N = 2,

And you were to object that this biconditional is false because some natural numbers are prime other than 2.

My name is Michael. The previous sentence is false.

They can't both be true. That would be a contradiction. If one is true then the other must be false.

but clearly this is possible, as I showed above

The example was a false analogy as the sentence mentioned was in a different language to the sentence used. In the schema I'm using the sentence mentioned on the one side is the sentence used on the other side.

@Michael, if I understand you correctly, your claim hinges on saying that the same sentence cannot exist in more than one language. Is that correct? — The Great Whatever

No. I'm saying that given the sentence mentioned on the one side is the sentence used on the other side, "X" is true iff X. That's not to say that some other schema won't work given that different sentences are used.

There is likely a missing premise that you cannot articulate, — The Great Whatever

I think there indeed is an additional premise that Michael is successfully articulating but that you keep ignoring, for some reason. The additional premise is that the languages of the used sentence and of the mentioned sentence are the same. When this additional premise, which amounts to a range restriction on the identity of the languages relied on to understand the sentences, is provided, then Michael's biconditional is true. The only trouble that was apparent to me was his earlier reliance on this biconditional to support some contentious counterfactual conditionals about, e.g., rabbits and horses.

No. I'm saying that given the sentence mentioned on the one side is the sentence used on the other side, "X" is true iff X. That's not to say that some other schema won't work given that different sentences are used. — Michael

I don't understand. I just showed above that this isn't true, by showing a counterexample. You responded that I switched sentences.

But I did not -- I used the same sentence, viz. "there are no dinosaurs," in both cases. In what sense are those two not the same sentence?

You say that one is in English, and the other is in the new English. I say this makes no sense -- the same sentence is being used in both languages.

No, I am not ignoring this; in fact I just explicitly addressed it above. I was using the same sentence in both cases, viz "there are no dinosaurs." So I do not see what Michael thinks this objection is buying him, or how it refutes what looks to me like a clear counterexample, in the face of which the biconditional is obviously not true.

I don't understand. I just showed above that this isn't true, by showing a counterexample. You responded that I switched sentences.

But I did not -- I used the same sentence, viz. "there are no dinosaurs," in both cases. In what sense are those two not the same sentence?

You say that one is in English, and the other is in the new English. I say this makes no sense -- the same sentence is being used in both languages. — The Great Whatever

That the same string of symbols are being used is not that the same sentence is being used. As you said, '"there are no more dinosaurs" means the same thing that "there are still dinosaurs" means now; that is, it means that there are still dinosaurs'. The sentence you're mentioning is in New English and the sentence you're using is in English.

But I'm telling you that the schema I'm using has the sentence mentioned and the sentence used in the same language.

My name is Michael. The previous sentence is false.

They can't both be true. That would be a contradiction. If one is true then the other must be false. — Michael

If by "the previous sentence," you mean the sentence "My name is Michael," (and what else could you mean?) then this would obviously not be a contradiction. Viz., if "My name is Michael" meant instead "my name is not Michael," then this sentence could be true in a situation in which your name was nonetheless not Michael (in fact, given what the sentence meant, it would have to be that your name wasn't Michael).

In the current situation, it is of course true that whenever this sentence is true, your name is Michael, but that is because the sentence meaning that your name is Michael, and having the form "My name is Michael," accidentally coincide in the language as it is spoken now. However, this is not necessary: in situations in which these things come apart, one can be true while the other is false.

The latter is the meat of your proposal: that in any situation in which the sentence is true, your name is Michael. But this is false.

(Also, don't use sentences with indexicals like "my," which makes your claim doubly false for obvious reasons, but I have ignored it here for clarity).

So are you claiming that a sentence is defined not just by the symbols that make it up, but also its meaning? Is a sentence something more than a certain string of symbols, or syntactic structure? Cannot the same sentence mean different things in different situations?

In the current situation, it is of course true that whenever this sentence is true, your name is Michael — The Great Whatever

Then we agree. What's left to discuss? Your criticisms are directed against straw men.

No, we do not agree; you intend the equivalence schema to mean that:

"X" is true

and

X

mean the same thing. As I have been at pains to show you, they do not. They are not equivalent, and one being true while the other false is in no way a contradiction. Getting to the point of this discussion, what this means is that how we use words like "horse" has nothing to do with what a horse is, or what it takes to be a horse. The latter is only intelligible if you mistakenly think, like you do, that the above two are somehow equal in meaning, rather than both accidentally being true at the same time in the present, in virtue of the current meaning of the sentence.

How many times do I have to qualify this? Given that the sentence mentioned on the one side is the sentence used on the other side, where 'being the same sentence' is to be understood as being in the same language – and so not where the meaning of the sentence mentioned is different to the meaning of the sentence used – "X" is true iff X.

You're consistently ignoring this and addressing a straw man analogy where the sentence mentioned and the sentence used mean different things. I'm explicitly not claiming that the T-schema formulation applies in these circumstances.

Okay, first of all, I am not ignoring anything, or attacking straw men. I have been replying to you patiently and in good faith.

Second of all, you are here confirming something that you a moment ago denied -- that your position depends on the claim that the same sentence cannot occur in more than one language. At least that seems to be what you say when you say this:

'being the same sentence' is to be understood as being in the same language — Michael

If I understand you correctly, your position hinges on a substantial thesis about the identity condition of sentences -- that the same sentence cannot exist in more than one language. Otherwise, the above counterexample works. Do you agree?

No, I don't, and I have no idea how you've come to that conclusion. It's a non sequitur.

How do you get from:

1) "X" is true iff X
2) The "X" mentioned on the left of the above and the "X" used on the right of the above are the same English sentence and so mean the same thing

To:

3) No other language can have a sentence which uses the string "X" or have a sentence which means the same thing as the English sentence "X"

I'm asserting 1) and 2).

3) doesn't follow.

The way I get from that is that this:

2) The "X" mentioned on the left of the above and the "X" used on the right of the above are the same English sentence and so mean the same thing — Michael

Makes no sense unless you assume the same sentence cannot mean two different things in two different situations. If one sentence can change meaning over time (which it seems to me it obviously can), then what you follow with, 'and so mean the same thing,' cannot be asserted.

Makes no sense unless you assume the same sentence cannot mean two different things in two different situations. If one sentence can change meaning over time (which it seems to me it obviously can), then what you follow with, 'and so mean the same thing,' cannot be asserted. — The Great Whatever

If I say that you and I have the same job, I'm not saying that you and I must always have the same job. So, when I say that the sentence mentioned means the same thing as the sentence used, I'm not saying that they must always mean the same thing.

But, given that they do mean the same thing, the T-schema holds; just as given that we do have the same job, we're both professional Xs.

So, as I have repeatedly said, given that the "X" mentioned on the one side means the same thing as the "X" used on the other side, "X" is true iff X.

Okay, so how does my counterexample fail, then? If you have a situation where the very same sentence, "there are still dinosaurs," which now means there are still dinosaurs, instead means that there are no more dinosaurs, then if we examine such a situation in which that sentence has that meaning, then it follows that even though that sentence ("there are still dinosaurs") is true in that situation, it is not the case that in that situation, there are still dinosaurs (in fact, the truth of the sentence in that situation demands that there are no more dinosaurs).

So in this situation, "X" is true, but it is not the case that X. -->

"There are still dinosaurs" is true, but it is not the case that there are still dinosaurs.

Therefore, the equivalence schema is false.

Okay, so how does my counterexample fail, then? If you have a situation where the very same sentence, "there are still dinosaurs," which now means there are still dinosaurs, instead means that there are no more dinosaurs — The Great Whatever

It fails as soon as you say "instead means that there are no more dinosaurs".

How many times do I have to repeat myself? The sentence mentioned means the same thing as the sentence used. So "there are still dinosaurs" means that there are still dinosaurs.

How many times do I have to repeat myself? The sentence mentioned means the same thing as the sentence used. So "there are still dinosaurs" means that there are still dinosaurs. — Michael

But you just said it doesn't always have to mean the same thing in the future. Ex hypothesi we are dealing with a situation in the future in which the sentence has changed meaning. You cannot simply stipulate that such a situation cannot happen; in fact you are committed to it being able to happen.

With respect to the language as we speak it now, I am not saying the sentence means two different things; nor am I switching sentences or even languages. All I am saying is that there is a possible situation in which that sentence is true, and yet it is not the case that there are still dinosaurs. This situation is imaginable, no matter what you say about the sentence being both mentioned and used has to mean the same thing now. And if you mean that the sentence mentioned and used have to mean the same thing always, you contradict what you just said above.

You cannot simply stipulate that such a situation cannot happen; in fact you are committed to it happening. — The Great Whatever

I'm not saying that it can't happen. I'm saying that the T-schema formulation that I'm using applies if the sentence mentioned means the same thing as the sentence used.

So, one last time:

If the sentence used on the left means the same thing as the sentence used on the right then "X" is true iff X.

As soon as you consider a case of the mentioned statement meaning something different to the used statement you're ignoring the antecedent of the material conditional.

I think you are confusing the purpose of the biconditional. Do you mean it as a material equivalence, or something like, 'for any situation, if the thing on the left of the biconditional holds in that situation, then so does the thing on the right?' If you mean it as a material conditional, then only the current situation is relevant, making your claim trivially true, and at odds with the more grandiose claims you made at the beginning of this thread.

If however you mean not a material conditional, but the 'in any situation...' claim, then adding this if-clause as a material condition does not help you. For this situation we're in now is a situation in which the antecedent is met; yet this situation would still be one in which the biconditional in the consequent is false, as I have showed you. So adding this condition does not seem to help you in the way you think it does.

Michael and TGW,

This sort of ambiguity about the individuation condition for sentences of a language can be circumvented with the use of the word "statement" to refer to speech act forms -- i.e. expressions of determinate thoughts in language. In that way, "Snow is white", as used by English speakers and "La neige est blanche", as used by French speakers, make the same statement using two different sentences. Conversely, the same sentence can be used to make two different statements in two different languages. When Michael thus refers to an "English sentence", he is talking about the statement that is made when this sentence is used by English speakers.

If you mean it as a material conditional, then only the current situation is relevant, making your claim trivially true, and at odds with the more grandiose claims you made at the beginning of this thread. — The Great Whatever

I know it's trivially true. I've been trying very hard to show how trivially true it is. And yet there's been so much disagreement. And I was never making any grandiose claims. I was making the same trivial claims that I'm making now. And yet there's been so much disagreement.

It has me exasperated.

No, you misunderstand me. You do not want to claim the material equivalence; if you do, then the claims you made earlier in this thread do not follow. In other words, your stronger claims have been about the two sides of the biconditional meaning the same thing, or causing contradiction if they differ in truth value, which a material equivalence does not guarantee.

For example, the following material equivalence is true:

Russia is the largest country in the world iff my name is Patrick.

So is this material equivalence:

London is in France iff Paris is in England.

But in the way you want to use the biconditional, that is, to claim an equivalence in meaning between the thing on the left and the right, such that there is no situation you can find in which Russia is the largest country in the world, but my name is not Patrick, or vice-versa, this equivalence is clearly false.

I think you are confusing the purpose of the biconditional. Do you mean it as a material equivalence, or something like, 'for any situation, if the thing on the left of the biconditional holds in that situation, then so does the thing on the right?' If you mean it as a material conditional, then only the current situation is relevant, making your claim trivially true, and at odds with the more grandiose claims you made at the beginning of this thread. — The Great Whatever

The way it is used in the literature on the philosophy of language and theories of truth, the disquotational shema always is meant to express a biconditional that holds over a range of possible worldly circumstances. It says of the mentioned sentence that it is properly evaluated as true in the object-language (i.e. it expresses a true statement with the use of the object-language) whenever, and only when, circumstances in the world are as described by the used sentence. So, you are free to interpret the biconditional form as the conjunction of two subjunctive conditionals, or as the statement of a material equivalence. You have to remember that the possible circumstances of evaluation range over ways the world might be (e.g. where Smokey the cat may or may not be on the mat) but hold fixed, and indeed uniquely determine, the semantic properties of object-language. (And that the meta-language also is held fixed ought to go without saying),

You do not want to claim the material equivalence — The Great Whatever

It follows from the premises:

1) if X then "X" is true and 2) if not X then "X" is not true

If the "X" mentioned and the "X" used mean the same thing then these two premises must be true else we have a contradiction. As per transposition 2) is equivalent to 3) "X" is true if X. 1) and 3) make for a material equivalence.

But in the way you want to use the biconditional, that is, to claim an equivalence in meaning between the thing on the left and the right

It's the fact that X and "X" is true mean the same thing (where the "X" mentioned and the "X" used mean the same thing) that justifies 1) and 2).

So in this sense I'm stepping beyond the T-schema and arguing for a logical equivalence rather than just a material equivalence (and so arguing for a deflationary approach).

So, you are free to interpret the biconditional form as the conjunction of two subjunctive conditionals, or as the statement of a material equivalence. — Pierre-Normand

Sorry for quoting myself, but I want to add this precision:

The intended interpretation as a conjunction of subjunctive conditionals is equivalent to saying that, in whatever worldly circumstances you might find yourself, then, in those specific circumstances, the T-shema interpreted as a statement of material equivalence must be true. And this means that the truth value of the mentioned sentence must be ascribed to it accordingly.

For instance, if you were to find yourself in circumstances where Smokey the cat is on the mat, then for the following statement of material equivalence to hold in those circumstances,

(1) "Smokey the cat is on the mat" is true iff Smokey the cat is on the mat

the truth value "true" must be ascribed to the sentence "Smokey the cat is on the mat" in order that it be properly interpreted and used as a statement in the object-language.

I know, that's what I just said. Point being, the logical equivalence is not trivial, and is wrong.

But I'm getting tired of this too. I still think you haven't answered the criticism and are fundamentally mistaken, but truth be told I don't really care that much.

What circumstances would that be? — Pierre-Normand

If there is no language.

Remember that philosophers who employ the disquotational schema (e.g. Tarskian truth theorists, disquotationalists, deflationists, minimalists, identity truth theorists, or prosentential truth theorists) are all using it in contexts where it is assumed that the truth conditions of the mentioned sentence are determined by means of the used sentence (on the right hand side of the biconditional). — Pierre-Normand

Yes, I know:

"P" is true if and only if P

But through biconditional elimination:

If P, then "P" is true

Which I have a problem with. Hence, the biconditional is problematic for me.

Hence, circumstances where its truth conditions would be different from the truth conditions of the used sentence are ruled out. — Pierre-Normand

They are ruled out because of the biconditional. Which is why it's also problematic to remove the biconditional and replace it with a material conditional. I don't want to allow the logical possibility of inappropriate truth conditions:

"P" is true if Q.

"The cat is on the mat" is true if the dog is on the bed.

So, it's rather like I were saying that if a natural number N is smaller than 3 then,

N is prime if and only if N = 2,

And you were to object that this biconditional is false because some natural numbers are prime other than 2. — Pierre-Normand

No, I don't think that that's a true analogy of my objection.

If there is no language. — Sapientia

There being language users in the vicinity is not a feature of the circumstances that has any relevance to evaluating whether the English sentence "Smokey the cat is on the mat" is true when Smokey the cat indeed is on the mat in those circumstances. We can imagine some circumstance in the distant past, in the distant future, or in a distant galaxy far away, when, or where, there are no language users around. If, in those actual or counterfactual circumstances, Smokey the cat is (was, or will be) on the mat, then the English sentence "Smokey the cat is (was, or will be) on the mat" as used by us now to describe what is (was, will be, or would have been) the case in to those actual or counterfactual circumstances is true.

They are ruled out because of the biconditional. Which is why it's also problematic to remove the biconditional and replace it with a material conditional. I don't want to allow the logical possibility of inappropriate truth conditions:

"P" is true if Q.

"The cat is on the mat" is true if the dog is on the bed. — Sapientia

I don't understand this. This last statement can't be derived from the disquotational shema where it is assumed that the mentioned sentence belongs to the same language as the language in which the truth conditions are stated. I think part of the confusion comes from your considering the mentioned sentence as a free standing material object, or uninterpreted syntactical object, such as an inscription on a billboard, that is envisioned to have different conventional meanings relative to the circumstances where it is being employed (e.g. in different cities where different languages are spoken). But the sentence being evaluated (and mentioned) rather always is the sentence used by us, in the present, and in English, in order to describe what is or would be the case in a variety of possible circumstances.