I am wondering how much of a nonstarter you think this argument is. I am also interested in suggestions concerning articles or books to read. (More recent works preferred, as I can follow their citations back in time as necessary.) You can speak very freely--though I do have a PhD in philosophy, it's been nearly a decade since I did any serious reading or tried to write for publication. So I'm currently back at the level of an eager grad student with some good instincts but no awareness of the lit.

  1. If tautologies are true, this is either due to how the world is or how linguistic conventions are.

2 If X is due to how Y is, then there is some way Y could be that would negate X.

  1. Tautologies are not true due to how the world is because there is no way the world could be that could make a tautology false.

  2. They also are not true due to how linguistic conventions are because there is no way linguistic conventions could be that could make a tautology false. (Changing the meaning of logical terms in the tautology would not make the tautology itself false, it would just make it no longer possible to express that tautology using those terms in that order.)

  3. So, tautologies are not true.

Obviously that seems like an incredible conclusion (literally) so to head off responses like "it's a non-starter because of its conclusion" I want to clarify, if the argument works I'd further argue that tautologies do have a truth-like property, they're truish, truthy, true-in-a-model, fictionally true, something along those lines. It's just that this truthlike property is not identical to the similar truth property held by empirical statements like "Kris weighs more than Julian."

BTW the most immediate cause of my conjuring up this weird argument is I am in the middle of reading Linguistic Conventionalism by Brett Topey (Phil Studies, 2018). I mention this in case it may give some context.

  • Premise 1 is the logical positivist version of the analytic/synthetic distinction famously criticized by Quine. Premise 2 with the parenthesized explanation in Premise 4 is false as applied to "truth by convention" (even if we admit that), or to necessary truths generally. Or, if you prefer, the argument is circular with the conclusion repeating this premise in disguise. – Conifold Jul 26 '20 at 22:30
  • Thanks those are very helpful remarks. I see what you mean about begging the question since "nec. truths are true due to the way the world is" is one of the very claims at stake in what I'm discussing. I guess I just don't really understand why people decided that (quoted) statement is true in the first place. That's probably what I need to find in the lit. I think Topey's citations probably will help but if you (or anyone) has a good overview you might know of, I'd love to hear about it. – user3752935 Jul 26 '20 at 23:24
  • In a way, "necessary truths are true due to the way the world is" can be justified by Quine's holism, where all truths, including logical and mathematical ones, are synthetic and ultimately stand before the "tribunal of experience". But I am not quite sure what references you are looking for. On linguistic conventionalism and its criticism? SEP has an article on Convention with a long bibliography. – Conifold Jul 27 '20 at 0:17
  • You may also want to look at Chalmers, Two-Dimensional Semantics:"According to Kripke, there are many statements that are knowable only empirically, but which are true in all possible worlds... Still... there remains a strong intuition that there is some way the world could turn out so that these terms would refer to different things... So there is a sense in which for a term like 'water', the term's extension and its Kripkean intension depend on the character of our world." – Conifold Jul 27 '20 at 0:39

Your premise 4 seems to be self-defeating. You say that linguistic conventions cannot make a tautology false because changing the meaning of the terms would express something different from the original tautology. But surely if the tautology cannot be made false then that is just what it is for the tautology to be always true.

The dichotomy between things being true because of how the world is or else by virtue of linguistic conventions sounds rather old-fashioned and naive, but let's run with it for the moment and consider an example. The sentence, (A) "the moon is made of cheese" is true or false in virtue of facts about the moon and cheese. By contrast, the sentence, (B) "the moon is made of cheese or it is not the case that the moon is made of cheese" does not depend on facts about the moon or cheese, but is true because of the way 'or' and 'not' work.

But what if we try to change the meaning of 'or' or 'not'? Then we could definitely make a false sentence: swapping the meaning of 'or' for 'and' would suffice. We could make the move that you suggest in your premise 4 and say that the tautology B has not been rendered false by this swap but rather that the sentence no longer expresses that tautology. However this amounts to saying that B is indeed always true because it is a tautology. We might perhaps imagine a community of people who speak a strange dialect of English in which 'and' and 'or' have their meanings reversed; when we say B it is true and when they say B it is false. But again this just means that B is a tautology and always true in our language, but not theirs.

In practice, logicians tend to sidestep all this talk of linguistic conventions by distinguishing between those components of sentences that are logical constants and those that are not. 'And', 'or', 'not', 'if', 'unless', etc., are distinctively logical terms. They are what we hold constant when we interpret propositions. Typically we might say that sentence B is a tautology because it is true under all interpretations: we can interpret 'moon' and 'cheese' to mean different things and the sentence still comes out true. But we don't try to reinterpret 'or' and 'not'.

That said, we can obtain different tautologies by adopting different logics. For example, "¬¬P → P" is a tautology of classical logic but not of intuitionistic logic. But then we probably would be inclined to say that intuitionists are changing the meaning of negation.

  • About self-defeat: That's an important point to address, but it assumes that if a tautology wasn't made false, then it remains true, and the idea that it was true in the first place is the thing under dispute in the argument. (The phrasing 'X isn't made true by Y' typically seems to rest on an assumption that X is true, but it doesn't strictly say or necessitate that.) As to the naive disjunction, that is what I'm getting the picture I'm going to need to do a bunch of reading about going back to some Quinean basics... – user3752935 Jul 27 '20 at 10:02
  • (Though I guess because the whole thing starts with "if they are true," that they are true is hypothetically assumed in line 4 as well. But in that case it's not self-defeat so much as proof by contradiction. Of course people usually take the relevant contradiction to prove either that P1 or P2 are wrong, I think, whereas I'm taking the hard road of saying it proves tautologies aren't true, exactly because the assumption they are is self-defeating. The present comment may be too compressed but stackexchange seems formatted not to really allow full discussion in comments which is fine.) – user3752935 Jul 27 '20 at 10:15

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