Nonsense and externalism (Language, Part VI)

is I will assume at first a fairly standard view of language, not my own weird view.

The following two claims are very plausible:

1. Whether a particular sequence of words from a language L expresses a proposition does not depend on anything other than facts about L.
2. A proposition is either true or false.

But in fact, (1) and (2) are not both true. For, consider the following line of words at the top of a page:

3. The next line of words expresses a true proposition.

Assuming a proposition is either true or false, it follows that whether (3) expresses a proposition depends on what the next line of words is. If the next line of words is "The sky is blue" or "Pigs can fly", then (3) expresses a proposition. But if the next line of words is

4. The previous line of words does not express a true proposition,

then (3) (or more precisely, the proposition expressed by (3)) can neither be true nor false. For if it is false, then the next line expresses a truth, and hence (3) is true. And if (3) is true, then (4) is true, and (3) is false. Since a proposition is either true or false, if (3) is followed by (4), (3) does not express a proposition. Thus, whether (3) expresses a proposition depends on what the next line of words is.

Observe that the two lines of words can be written independently by two different people. Thus, whether a sequence of words uttered by me expresses a proposition can depend on what someone else says—even on what someone else says later, assuming (2).

We thus need to reject either (1) or (2) or both. In fact, I think we should reject (1). Rejecting (2) forces a non-classical logic. Call a sequence of words that does not express a proposition "nonsense". Then what we have learned is that whether a sequence of words is nonsense can depend on non-linguistic facts about the external world. Thus, just as we learned from Kripke that judging whether a proposition is possible is not in general a matter for an armchair investigator, so, too, judging whether a sequence of words is nonsense is not in general a matter for an armchair investigator.

Or at least that's what happens if one has a standard view of language. I myself have a non-standard one. On my view engaging in sentential anaphora (as in (3)) makes the anaphorically referred-to sentence be a part of one's own sentence—it is a way of taking up another's words and making them one's own. This is a version of deflationism. (By the way, I love the joke about deflationary semantics of "true". You want to be famous? You write a paper that says: "Everything Brandom says in his next paper is true." Then when Brandom publishes his paper, you say: "He's right, but I said it first.")

This all works a bit better on an eternalist theory of time.