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Has anyone done any good work on tensed expressions and how they combine? Under another name, I did ask a few questions about tense, and am clearly confused by it. and hope that an answer to this pursuit will help me think clearly about 'tense'.

e.g. how is the following deformed?

  1. 'I am dead' is nonsense, a logically contradictory thought.
  2. So 'I am dead' is never true.
  3. Any tensed expression (I am dead) will be true, in the future, if is true in the future tense (I will be dead).
  4. So 'I will be dead' is not true.
  • i'm guessing this pseudo-argument is deformed, most of all, by an assumption that nonsense is always nonsense. is that right? – user29495 Nov 13 '17 at 17:52
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    Logic of tense is called temporal logic. But the problem is neither with nonsense nor with tenses but with equivocation on indexical expressions like "I" or "this", logical generalities like 3 assume fixed reference. While 'I am dead' can never be truthfully uttered if we fix the reference of "I" at the time 'I will be dead' is uttered it may well (and usually does) become true (albeit unutterable). So depending on interpretation of "I" either 2 is false or 3 does not apply. – Conifold Nov 13 '17 at 19:21
  • @Conifold i get that we want to say there's an equivocation there, but was looking for a perfect elaboration of that – user29495 Nov 13 '17 at 19:26
  • Not to blow my own horn, but I think my answer below expands on @Conifold’s point. – MarkOxford Nov 13 '17 at 19:55
  • @MarkOxford thanks for the answer, it was good, hope the edit is inoffensive – user29495 Nov 13 '17 at 22:59
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One problem is the third premise: if you believe in an open future, you may also believe that ‘p will be true at t’ has no truth-value – although p will acquire a truth value at t. Setting this aside, I think the use the first-person pronoun ‘I’ gives rise to some trouble. (As a quick way to see this, just try to run the argument with e.g. ‘Frank is dead’ instead of ‘I am dead’.)

If a sentence contains an indexical like ‘I’ (or ‘now’ or ‘here’), we can’t ever say that the sentence is true or false simpliciter: we can only say that it is true (or false) at a given context c. In turn, a context (according to the common definition) is an ordered n-tuple, containing at least an agent, a time, and a possible world. (It might contain other stuff like a location, an epistemic standard, etc.) At a given context c, e.g. ‘I am home now’ then expresses that the agent of c is home at the time of c.

Importantly, the ‘agent’ of a given context c needn’t be saying anything at the time of c. In fact, it’s not even clear that the agent of c has to exist at the time of c in the world of c. (Kaplan thought they must, but people have found good reasons to disagree.) Because of this, a sentence like ‘I say nothing’ or ‘I am not talking now’ will turn out true at some contexts – viz. at all contexts c where the agent of c is silent (at the time of c). And that’s a good thing: otherwise the sentences would be logical falsehoods according to the logic of indexicals!

With this in mind, we can return to your ‘I am dead now’. While there are no true utterances of this sentence, there arguably are contexts at which the sentence is true – viz. all those contexts c where the agent of c is dead (at the time of c).

In sum, there are ‘future contexts’ at which ‘I am dead now’ is true. Thus, even if we accept the third premise, the conclusion still doesn’t follow.

  • nice language, but i don't see what you've added to the question. that indexicals have a context i would agree. that in some contexts "i am dead" is true, is the point of contention, so i don't see that as a useful dis-equivocation .and not sure why you avoided use of 'nonsense' – user29495 Nov 13 '17 at 22:40
  • so in conclusion, can't see how you've shown that nonsense indexical expressions are never true. your examples like "i am not speaking" aren't nonsense, they are false. i would guess anyway. i've upvoted, tho – user29495 Nov 13 '17 at 22:43
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    ‘I am dead’ is no more nonsensical than ‘I am on Mars’: both are false in contexts where a living Earthling is the speaker; but they are perfectly meaningful English sentences. What I (and conifold) tried to point out was that according to the mainstream semantic theory of indexicals, ‘I am dead’ is true at some contexts. You can reject that theory – if you can offer an equally good replacement. But why would you want that? It has the added advantage of answering the original question of why the argument is not valid (or, ‘deformed’). – MarkOxford Nov 13 '17 at 23:01
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Your problem is that 4 does not follow from 2 & 3.

Note that 3 only applies to true tensed expressions. As 2 isn't true, 3 doesn't apply to it so you can't use it to get to 4.

Now, if 2 was "I am alive", which is currently true, then you can use 3 to get to "I will be alive".

As none of 2, 3 or 4 apply to nonsense, 1 doesn't really add anything here.

  • Under 3 'I will be dead' can only be true iff 'I am dead' is true in its future. If 'I am dead' is assumed to be not true at any time it does follow that so is 'I will be dead'. – Conifold Nov 13 '17 at 19:11
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Just to add my two cents to the helpful answer/s above.

Today is yesterday is an example of an indexical which is nonsense in I think the same way.

Today will be yesterday, however.

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