Tuesday, August 20, 2013

deep semantics 2: entailment vs. invited inference in barrier verbs

This is the sixth in a series of posts detailing data and analysis from my not-quite-entirely-completely-achieved linguistics dissertation (list of previous posts here).

Recall that if an entity wants to achieve a certain outcome, yet is impeded by some force, this situation can be encoded by a barrier verb in English, such as prevent, ban, protect.

Deep Semantics 2: Entailment vs. Invited Inference

Even though barrier verbs appear to be clearly Negative verbs (see here), I will be careful not to overstate the logical relationship between the negative semantics of barrier verbs and the outcome of the complement event because in some cases the relationship seems like entailment, but in others it seems closer to invited inference. For example, in (a) it seems like the verb prevent entails that the car did not get wet; however, in (b), it seems plausible that, while Tom may be exempted from paying taxes, he went ahead and paid them anyway (perhaps by mistake).
(a) The garage prevented the car from getting wet.
(b) The IRS exempted Tom from paying taxes.
Simple presupposition involves the existence of some assertion in the background knowledge of all people involved which allows another assertion to be true. Here is a classic example from Chierchia and McConnell-Ginet 1990:
ASSERTION - Tom stopped smoking.
In order to utter “Tom stopped smoking” felicitously, it must be assumed that the listener already knows that “Tom smoked”. In the example below, the barrier verb ban requires, on some level, the listener to believe that the journalists want to go to the courtroom:
ASSERTION - The judge banned journalists from her courtroom.
PRESUPPOSITION - The journalists want to go to the courtroom.
And, indeed, this belief passes the three primary tests for presuppositions:
NEGATION: The judge did not ban journalists from her courtroom.
QUESTIONING: Did the judge ban journalists from her courtroom?
CONDITIONAL: If the judge banned journalists from his courtroom, then their will be trouble.
The presupposition “the journalists want to enter the judge’s courtroom” survives under all three of these tests, but this alone does not mean that it is presupposed. There are presupposition-like phenomena which produce the same or nearly the same results. For example, if a person I don’t know very well came up to me and said, “my father just stopped smoking recently” I could infer (from Grice’s well known maxims of QUALITY and QUANTITY most likely) that her father had smoked previously and add that assertion to my background knowledge thereby making her utterance felicitous (and she could assume all along that that is exactly what I would do, also making her utterance felicitous). The assertion is not presupposed per se, but it is inferred and added to background knowledge in the moment.

One alternative is typically referred to as invited inference which mirrors many of the properties of presuppositions. Invited inferences are inferences we make based on background knowledge and our desire to follow basic principles of cooperative communication (ala Grice’s maxims). They can be very dependent on the verb they occur with. Saeed cites Levinson 1983 for the following examples:
ASSERTION - He cried before he finished his thesis.PRESUPPOSITION = He finished his thesis
ASSERTION - She died before she finished her thesis.
PRESUPPOSITION ≠ She finished her thesis.
Based on our knowledge of the world, we can recover or infer the fact that she did not finish in the second sentence. One possible analysis, that can save the presupposition, is defeasibility.

Defeasibility says, in essence, we do in fact make the same presupposition for the second sentence, but then we cancel it after checking with world knowledge. To test whether there is a consistent presupposition with all the barrier verbs, I performed the three presupposition tests above on a sub-set of all the barrier verbs in a preliminary NYT corpus. The goal was to perform the tests on two active sentences for each verb, preferably one with an NP complement and one with a VBG complement. This was not always possible, either because some verbs had no variation in complements in this corpus or there was a scarcity of active sentences (often these verbs are found in the passive or in nominals) or there was only one sentence found in the corpus for a particular verb (e.g., “to guard”). In the cases where there was no variation, two sentences with the same complement type were used. In the case where there was no good active sentence, one was formed from a passive with minimal adjustment (you will forgive this linguistic slight of hand as no change in the relevant meaning resulted. FYI, see Nunes* for a relevant discussion of the argument structure of deverbal nominal).

In the cases where only one sentence was available, the tests were performed on that one sentence and then the study proceeded on to the next verb. In all cases, a presupposition was contrived that could survive all the tests. Take, for example, the one sentence involving the verb guard:
Lavish and extensive measures guard the president from myriad threats.
If we take the “the president” to have a tendency away from “the myriad threats”, then how is that tendency to be paraphrased so as to test it with the presuppositions? As these tests are linguistic in nature, the linguistic form of the paraphrase of the situation feature of tendency is rather important to make sure the tests are being performed correctly. We might say that the assertion p is presupposed: p = The president wants to avoid threats.
NEGATION: Lavish and extensive measures do not guard the president from myriad threats.
QUESTIONING: Is it the case lavish and extensive measures guard the president from myriad threats?
IF/THEN: If lavish and extensive measures guard the president from myriad threats, then there’s going to be trouble.
One fine distinction can be made regarding speech-act barrier verbs like ban and exempt where it is possible that the undergoer of the prohibition is either not aware of it or chooses to flout it. This allows for the possibility that the prohibited event occurs despite the ban, making the negation of the event an invited inference rather than an entailment.

Thus, the jury is heavily leaning towards entailment for most core barrier verbs, but the jury is still out.

* Nunes, M. 1993. Argument Linking in English Derived Nominals. In Van Valin (ed) Advances in Role and Reference Grammar, John Benjamins, 375-432.


Bert Cappelle said...

Hi again Chris,
This is really fascinating stuff. I'm intrigued by the contrast between prevent and exempt. I would also advocate an entailment analysis for most core barrier verbs, which then kind of tapers off into mere invited inference for others. One may be reminded here of Adele Goldberg's classic polysemy analysis of ditransitive verbs, which all hinge on transfer, just like your barrier verbs all somehow involve the negation of the complement. With the core ditransitive verbs, such as give, there is actual transfer, but with others, there's just an enabling sense (e.g. permit), a focus on a satisfation condition (e.g. promise), an intended transfer meaning (e.g. bake), etc. Her polysemy approach could fairly easily be reformulated, along your lines, in terms of a transfer entailment for core ditransitives and invited inference for others. However, this dichotomy may run into problems for ditransitive like refuse, which neither entail actualized transfer nor invite actualized transfer to be inferred. (Rather, it's about causing NOT to receive.) But as long as no peripheral barrier verbs involve the negation of negation, your semantic analysis ("entailment of negation for core barrier verbs; invited inference of negation for others") can be maintained.

Bert Cappelle said...

Hi again,

Right after submitting my previous comment, I was left wondering about the existence of some more peripheral barrier verbs for which there may not even be any invited inference (i.e., of negation of the complement proposition). I think slow may be such a verb. Consider the following example:

(1) Keep in mind that refrigeration doesn't kill bacteria, but it stops or slows them from growing. (www)

In (1), we have two happily juxtaposed barrier verbs, stop and slow. While the first entails negation of growing, the second does not. In fact, it doesn't even quite allow one to infer negation of the complement proposition. Or does it? Its meaning is something like this: 'the complement proposition, which needs to be inherently scalar in some dimension, is negated with respect to some salient degree of actualization'. In (1), what's possibly negated by slow is that the rate of growth is as before (the impeding process of refrigeration). But what is definitely not entailed or even implicated by slow as opposed to stop is that there's no situation of growing anymore at all.

This would mean that a semantic analysis of barrier verbs requires rich semantic information to be included in the individual verbs, rather than classifying them as belonging to an "entailment" set vs. an "invited inference" set. Nevertheless, the latter may be an interesting step towards getting at the meaning of individual barrier verbs.


Chris said...

Good stuff Bert. I'm going to chew on this tonight.

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