If 'right' meant wrong, then the sentence "murder is right" would be true, but that wouldn't make murder right. For my latter (disquoted) use of the word 'right' is spoken in my actual language. It picks out a property that murder lacks no matter what we call it. The earlier, quoted mentions of the word 'right' (i.e. my uses of ''right'') are not used to express this property. They instead refer to the word itself. And if this word were to pick out the property of wrongness, i.e. the property that is actually denoted by our word 'wrong', then the former word would extend to murder. That is, if 'right' meant wrong, then 'right' would pick out a property, namely wrongness, that murder has. But again, that obviously wouldn't make murder right. Murder would not gain the property that we actually refer to using 'right'. It would merely become describable using the word just mentioned -- a word that would then be used to mean the opposite of what it means in actual use.
So much for counterfactual languages. What about counter-actual ones, i.e. other languages considered as actual, say using indicative conditionals? To borrow an example from Yablo, compare:
(1) If 'tail' had meant wing, then horses would not have had tails.
(2) If 'tail' means wing, then horses do not have tails.
Clearly (1) is false, for the reasons explained above. But what about (2)? Yablo argues that it's true:
If 'tail' as a matter of fact means wing, then to say that horses have tails is to say that they have wings. Horses do not have wings. So if 'tail' means wing, then horses do not have tails. ('Coulda, Woulda, Shoulda', p.450)
Here's a puzzle: our actual use of 'horses do not have tails' is (near enough to) synonymous with 'horses lack post-trunk extensions'. But now consider:
(2*) If 'tail' means wing, then horses lack post-trunk extensions.
That claim is surely false. And substituting synonyms shouldn't alter the truth value of a sentence, so (2) should be false too. But perhaps this is an exception to that general rule, rather like:
(3) 'tail' has four letters.
(3*) 'post-trunk extension' has four letters.
But the obvious problem with (3*) is that the substitution occurs within quote-marks, wherein the word 'tail' is being mentioned rather than used. (What's being used is the string ''tail'', and the replacement string ''post-trunk extension'' is not synonymous with that. Rather than referring to one and the same body part, these two terms refer to two different words. Whereas 'tails' refers to tails, ''tails'' merely refers to 'tails'. Don't let the superficial similarity fool you!) The substitution from (2) to (2*) is not illegitimate in this way. So if it is illegitimate at all, we need some further explanation why. The mere fact that the word is mentioned earlier in the sentence does not suffice. For compare:
(4) 'Four' has four letters.
(4*) 'Four' has 3+1 letters.
There's clearly nothing wrong with moving from (4) to (4*), despite the early mention of the word that gets substituted when used later in the sentence.
If we accept the equivalence of (2) and (2*), then we will reject Yablo's first premise: "If 'tail' as a matter of fact means wing, then to say that horses have tails is to say that they have wings." This seems a tough bullet to bite, but perhaps it is defensible. After all, that horses have tails is the same proposition as that horses have post-trunk extensions. To say one is to say the other, as they are one and the same thing. But to say that horses have post-trunk extensions (tails), no matter what particular language one says this in, is not to say that they have wings.
My argument here is a little suspicious, since it seems like I'm not giving the antecedents of Yablo's indicative conditionals due weight -- it might be suggested that they undermine my synonymy claims, thereby blocking my response. I'm not too sure what to think of that. I guess there must be something wrong with the substitutions after all, but I'd welcome any clear insights into what exactly the rule broken by (2*) is...