The reason I suggested that for Part 2 of Homework 8 you consider a sentence like John did not find Mary instead of the actual sentence (John did not like Mary) is that the intuitions are quite a bit clearer, and make the point a bit more forcefully.

This point was made even more clearly in a question I just got over email: It’s perfectly sensible to say something like John didn’t like Mary, but he does now. If you think about this a bit, it would seem to run somewhat counter to the conclusion you get for John didn’t find Mary, and might suggest that both of the options (tense over negation, and negation over tense) are possible. That is, for find we want the sentence to mean something along the lines of John never found Mary (all the way up to now). But it seems like we might not want to force John did not like Mary to necessarily mean John never liked Mary (all the way up to now).

I still claim that only one of the options is possible, but we do need to say something about why you can say John didn’t like Mary, but he does now. This was part of what I planned to talk about tomorrow, but the basic idea is that past tense isn’t really talking about all time prior to now, but seems to be rather about a certain interval of time determined by the context. This was the force of the example I didn’t turn off the stove (spoken by somebody who is driving away for the weekend). This doesn’t mean “I have never turned off the stove in my life”, but rather it means that during the relevant past time interval (the time during the preparations for leaving), there were no turnings off of the stove.

So, for John didn’t like Mary, what I think that means is that during the whole (past part) of some relevant time interval, there was no time in that interval when John liked Mary. If the entire interval is completely before now, however, that’s not incompatible with the possibility that John likes Mary now.

The bottom line is that what I’m asking you do to in Part 2 of Homework 8 is, I believe, still true and valid, but the fact that I asked you do it with a sentence involving the state-verb like (rather than the punctual find) made it quite a bit easier to imagine the contextually relevant interval as being one that does not overlap with the utterance time, and therefore makes the judgment quite a bit harder. In principle, the same thing is true of John did not find Mary as well. If John and Mary are playing hide and seek, you can talk about the outcome of the second of three games played in the past by saying John did not find Mary, even if John found Mary in the first and third games. What that means is that during the entire interval of time occupied by the second game, there were no findings of Mary by John.

Anyway, this is kind of an extra complication, which we’ll discuss in more detail in class tomorrow when we finally address modals.