Assertion and Rejection
Julian Schlöder

Abstract:
This thesis discusses the interplay between the speech acts of assertion and
rejection. First, it defends that it is even sensible to distinguish these two
speech acts, against an old consensus---going back to Frege---that rejection is
merely negative assertion. To this end, I introduce the speech act of weak
rejection and defend it against its critics. Based on this notion, I develop a
logic of asserted and rejected content---weak bilateral logic---and demonstrate
its usefulness in the analysis of natural language inferences.

To make this result accessible to a general theory of linguistic interaction, I
give an alternative characterisation of weak rejection in a theory of public
commitment. I develop a broad theory of commitment from independent, basic
principles that hold even in non-cooperative dialogue contexts. These principles
predict compelling dynamic-interactive properties of the speech acts of
assertion and rejection, and moreover validate weak bilateral logic as the logic
that preserves cooperative commitment. This theory is further rounded out by a
theory of Why-questions that explains what it means to be able to vindicate
one's commitments.

Then, I develop these investigations further by pairing weak rejection with its
dual speech act: weak assertion. This generalises weak bilateral logic to
epistemic multilateral logic. This logic has two major upshots: it defends
classical logic as the logic of asserted content against arguments from harmony,
while simultaneously explaining epistemic modals. This is grounds to re-evaluate
a growing collection of data that alleges the incompatibility of classical logic
and a satisfactory semantics for epistemic modals.

Another challenge to classical semantic theory is the faultless disagreement
argument. Famously, judgements about taste (and similar properties) have
linguistic and interactional properties that appear to distinguish them from
other judgements. Some have argued that this calls for wide revisions of
semantic theory. I show that this is not necessarily the case. Using a public
commitment framework, I develop a theory of reframable predicates and specify
the dialogue dynamics of such predicates. Then, if one accepts that taste
predicates are reframable---as suggested by the available data---one can explain
the relevant phenomena without revising semantic theory.

Finally, I address a methodological issue. Sometimes, written records of certain
utterances can be ambiguous between agreement and disagreement: how they were
said makes the difference. Intonation is rarely annotated and, if so, it is
frequently only the placement of the focal stress that is recorded, but not the
utterance tune that sets the focus. I demonstrate that foregoing tune can lead
to confusion: the interpretation of an utterance with the same focal stress can
vary depending on the tune. Thus, one needs a unified theory of focus and tune.
I develop a first attempt towards a formal discourse theory of focus and tune
that already explains a number of interesting tunes, including one that signals
verbal irony. This theory in particular explains relevant data on agreement
and disagreement.