It can't be false. It follows from premises which can't be false. — Michael
So, if your argument is valid, then at the time, at least one of the premises must have been false. — Sapientia
The contrary is far too implausible to accept.
They can't be false else we'd have a contradiction.
"P" is true if P
"P" is false if not P. — Michael
Then there is no T-schema to be false. So, as I said, the T-schema must always be true. — Michael
I didn't say that there was a T-schema. — Sapientia
You have claimed or implied that the T-schema would apply at such a time, and I have rejected that.
It would've been the case that the pre-linguistic universe exists, but there wouldn't have been a corresponding true sentence.
You said "[t]he conclusion [the T-schema] was false at the time" (and "at the time, at least one of the premises must have been false"). How could it (or they) be false if they weren't "there"? — Michael
No I didn't. I have only ever said "X" is true iff X (and X iff "X" is true). I've never said X iff "'X' is true iff X" is said and is true. — Michael
Which is why I said that the pre-linguistic universe existed iff "the pre-linguistic universe existed" is true and not that the pre-linguistic universe existed iff there was a corresponding true sentence at the time. — Michael
Also, I think your tense is wrong again. Would it have been the case that the pre-linguistic universe exists? Compare with; would have been the case that the Nazis win the war. Does that make sense? I don't think so. Should be; would have been the case that the Nazis won the war, and so; would have been the case that the pre-linguistic universe existed. — Michael
There were facts, but no sentences, and therefore no true sentences.
What's the problem?! — Sapientia
That's misleading. The universe existed, and, at the time, it would be the case that the universe exists. Similarly, the Nazis shot Jews, and, at the time, it would be the case that the Nazis are shooting Jews
The problem is that I've never said that there were true sentences, and nor have I implied it. I've simply taken two necessarily true propositions and performed the relevant logical manipulations. — Michael
A subjunctive conditional is a counterfactual conditional, and the T-schema doesn't seem to use a counterfactual conditional. If it did (pun intended) it would look like this: — Michael
Where does my logic fail? You say that "the cat is on the mat" would be false if the cat were not on the mat, and so we have ¬C > ¬P (using the subjunctive conditional). As per transposition this is equivalent to P > C, which is that the cat would not be on the mat if 'the cat is on the mat' would be false". — Michael
Hence, you are licensed to say, on the basis of the T-shema instanciation previously discussed, that in all cases where Smokey the cat is (or would be) on the mat, "Smokey the cat is on the mat" (in English) is (or would be) true, and in all cases where Smokey the cat isn't (or wouldn't be) on the mat, "Smokey the cat is on the mat" (in English) is (or would be) false. — Pierre-Normand
That's because instanciations of the T-shema (as derived from the meaning assignment axioms of the theory) are meant to be interpreted as a recipe, or instruction manual, that tells you how, given specific worldly circumstances (e.g. circumstances either actual or counterfactual where horses are or aren't rabbits, or where Smokey the cat is or isn't on the mat) sentences in the object language ought to be evaluated as true or false.
If you say that they're the same, then I'll say that "yes" and "no" are the same. It's just as contradictory, in my view - unless the meanings are changed so that they mean the same thing. — Sapientia
If dinosaurs were roaming the earth (to use Michael's example), does it follow that "dinosaurs roam the earth" was true, or merely that "dinosaurs roamed the earth" is true? — John
Get involved in philosophical discussions about knowledge, truth, language, consciousness, science, politics, religion, logic and mathematics, art, history, and lots more. No ads, no clutter, and very little agreement — just fascinating conversations.