HW8: Making sure that John did not find Mary is not always true

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At the end of the statement about homework 8, I said that we want to make sure that John did not find Mary is not always true. To clarify what I mean here: In our task of formalizing our intuitions about meaning, we don’t want our semantic system to predict that John did not find Mary is true in this situation:

<----past----------now--->
   John finds
   Mary

It seems very clear from our intuitions about what this sentence would mean that if anything, that situation illustrated above is the best example of one in which John did not find Mary is false. But if we’re not careful, our semantics will predict that it would be true (on one reading of the sentence). That would be a bad prediction.

Edit: I changed the wording below a bit to reflect the change in the subsequent blog post.

If we allow Tense Raising and Neg Raising to occur in either order, or targeting either S in the structure, we predict that the sentence would have a reading that is true in the above situation. That is, one order (of Neg and Tense in the final structure) results in truth conditions that the illustration above would satisfy. What we need to do is stipulate that the final structure has to be one where Neg is above Tense, or stipulate that the final structure has to be one where Tense is above Neg one of the two rules (Tense Raising, Neg Raising) has to apply last—the question (in Part Two) is really asking which one has to wind up lower apply last. (And to sort of explain the problem that arises if the rules are applied in the wrong order—that is, why the situation above would turn out to meet the truth conditions.)

The property that the situation above has that’s relevant is that, although there is a moment in the past where John finds Mary, there are also plenty of moments in the past where John doesn’t find Mary. We have to make sure that the existence of such non-finding moments doesn’t render the sentence true. So, we have to stipulate a fixed order in the final structure between Neg and Tense to avoid that between Neg Raising and Tense Raising to avoid that.