Logic & Philosophy of Science Colloquium
Massachusetts Institute of Technology
"Presuppositions, Truth Values, and Expressing Propositions"
One of the familiar parts of the philosopher's toolkit is the idea that some
class of sentences fail to express propositions in certain contexts. This
tool has been applied to a wide range of issues, from problems in
philosophical logic such as vagueness, semantic paradox, and indicative
conditionals, to expressivism in moral theory. Traditionally, the notion of
failing to express a proposition has been linked to two other important
notions: the pragmatic notion of presupposition, and truth value. A common
traditional picture is that when an assertion fails to express a proposition
in some context, it is because of presupposition failure in the context.
Presupposition failure, in turn, is indicated by lack of truth value.
However, more recent work has significantly complicated the traditional
picture. Research in philosophy of language and linguistics has shown the
notion of presupposition to be rich and diverse, in ways that obscure its
relation to truth-value judgments and the intuitive notion of expressing a
proposition in a context.
In this essay, I shall investigate the relation between the philosophical
notion of expressing a proposition and the linguistic notion of
presupposition. In doing so, I shall pursue three linked goals. First, I
shall offer an analysis of the philosophical notion of failing to express a
proposition. Second, I shall offer an account of how failure to express a
proposition may be recognized in natural language, by way of some
discourse-based diagnostics which are more robust and reliable than simple
truth-value judgments. Third, I shall attempt to document what gives rise to
the phenomenon of expression failure. This third part of the essay will
involved some detailed investigation into presupposition. I shall show that
some presupposition failures lead to expression failure, but some do not. I
shall go on to offer an analysis of elementary presuppositions which explains
why presuppositions fall into these two categories. This will involve close
examination of some important cases of presupposition: clefts, factive verbs,
demonstratives, and presuppositions generated by conventional implicatures
such as those of 'too', and 'even'. I shall conclude the third part of the
essay with some speculation about the relation of conventional implicature to
Much of the work in this essay is thus dedicated to detailed investigation
presupposition, which is one of the central aspects of context dependence.
But in shedding light on the connection between presupposition and the notion
of failing to express a proposition, I hope to add some substance to a
sometimes-contentious part of the philosopher's toolkit as well.
Friday, April 4, 2003
Refreshments will be served