Presuppositions in Spoken Discourse

Chapter 4
anaphors, suggesting that other factors can also be involved. What about
presuppositions in this regard? Example (26) with the bound presupposition (and
possibly other examples of bound presuppositions will be similar) differs in one
substantial ways. We don’t necessarily have to return to the earlier context and bind
with the antecedent to understand the discourse in (26) because we can always
accommodate, and we certainly have enough information to do so. So unlike the
pronominal return pops there is no need to account for the great distance between
presuppositional information and its antecedent by assuming a hierarchical
structure. This makes one of the main reasons for assuming return pops in the first
place irrelevant for presuppositional expressions like the one in (26).
Evaluating Asher & Lascarides’ claim that presuppositions take their
antecedents from the right frontier is quite difficult to test. This and similar
proposals for anaphors (e.g., Grosz & Sidner (1986), Polanyi (1988)) all use madeup
spoken discourses to illustrate their approaches. Fox (1987) looks at naturally
produced unrestricted dialogues, but she doesn’t specify explicitly a structure and
she doesn’t make claims relating structure to anaphoric accessibility either. It is easy
to construct a tree structure, or simulate a focus stack, for a made-up discourse, but
it is much harder to determine if antecedents are found in the appropriate position
in natural discourse due to its greater complexity. There does not seem to be any
empirical work which tests the proposals and claims on large corpora, maybe due
to the difficulty of the task. Eckert & Strube’s (2000) work on resolving abstract
object anaphors in spoken discourse seems to show however that a simplified local
discourse structure is sufficient to correctly identify the antecedents of abstract
anaphoric referents in over 60% of the cases. 13
If we assume that pronouns, especially those that refer to abstract objects,
take antecedents only from the right frontier, we have a problem explaining cases
where a presuppositional expression cannot be replaced with a pronominal
anaphor. If there is evidence that the presupposition is bound with the antecedent
found, then we have to consider this to be evidence that bound presuppositions are
not governed by the same constraints as pronouns on the location of antecedents.
Examples already given include (24) and even more strikingly (22). That is,
presuppositional information might be limited in where in the discourse structure it
can get antecedent information, but these examples seem to show that this limiting
effect cannot be the same for presuppositions as for pronouns, either it is different,
or it does not affect presuppositions.
In conclusion, it is not at all clear that some type of hierarchical structure is
necessary to account for antecedent accessibility for anaphoric pronouns and there
is also no evidence in the corpus that hierarchical structure is necessary for limiting
the availability of antecedents for presuppositions. The examples where it was not
13 Precision for Eckert & Strube’s (2000) algorithm was 63.6% and recall was 70%. One of the
explanations they give for these low percentages is that they limited the domain in which to
search for antecedents to one synchronizing unit, a kind of adjacency pair similar to the discourse
segments defined earlier. But they point out that this restriction is also what allowed them to do
so well in classifying.
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