Presuppositions in Spoken Discourse

Chapter 2
effects of alternative candidates on the winning output, and a good introduction
can be found in Archangeli & Langendoen (1997). Other frameworks generally
treat candidate expressions or interpretations in isolation. Blutner argues that an
awareness of alternatives in both production and interpretation can in part account
for cases where a presuppositional expression is felt to be somehow pragmatically
anomalous.
Basic OT has three key components, Gen, Con, and Eval. Gen generates all
potential candidate outputs for a given input. Con is a ranked set of constraints
that Eval then uses to evaluate each candidate to determine the optimal output for
the given input. OT constraints are soft constraints, meaning they can be violated.
OT-syntax and OT-semantics are uni-directional forms of OT. OT-syntax takes a
given meaning and then evaluates candidates to determine the optimal form for
expressing this meaning, i.e. taking the perspective of the speaker in production.
OT-semantics takes a form and then evaluates candidate meanings to determine
what would be the best interpretation, i.e. taking the perspective of the hearer in
comprehension. The evaluation process is represented in a tableau where candidate
outputs are listed along with the constraints relevant to their evaluation.
Blutner (2000) proposes a bidirectional version of OT where forminterpretation
pairs are evaluated in relation to other candidate form-interpretation
pairs. A superoptimal pair 〈 A, τ 〉 is a pair where a given form A is always optimally
interpreted as leading to an output τ, and vice versa, e.g. generating an expression
to reach an output context τ is always optimally done with form A, and vice versa.
Two constraints cover the main needs of presupposition interpretation, AVOID
ACCOMMODATION (AVOIDA) and BE STRONG (explanations given below adapted
from Blutner, 2000, p. 209).
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AVOIDACCOMMODATION (AVOIDA): Count each discourse marker that
must be accommodated as a violation.
BE STRONG : Evaluate pairs 〈 A, τ 〉 with stronger outputs τ higher than
pairs with weaker ones.
The first constraint captures the preference for binding over accommodation, and
the second captures the idea that speakers will prefer stronger interpretations over
weaker ones, believed by some to be at the root of a preference for higher levels of
accommodation, over lower ones, discussed in more detail in section 5.4. AVOIDA
is ranked higher than BE STRONG.
Tableau 1 illustrates a simple example of an OT interpretation of a
presupposition triggered in the consequent of a conditional in an empty context.
This example is based on Blutner’s 2000, example (17), (p. 209). There are three
candidate interpretations, global, intermediate and local accommodation for one
form, (here we are not comparing form-interpretation pairs but only unidirectionally
what interpretation would be optimal).