Philosophy of Language: Vagueness and Truth

In recent years the issue of vagueness has become a hot topic among
analytic philosophers.  Much of this interest seems to stems from
worries about sorites paradoxes.  Consider the property of
baldness.  A person with a full head of hair is not bald. A person
without a single hair on her/his head is bald. It’s hard to see how
the loss of a single hair could ever make a non-bald person bald.
These seem a pretty safe set of assumptions.  Yet accepting them
leads almost immediately to paradox.  Consider someone who is not
bald and who, at regular intervals, loses one hair at a time.  Since
no individual loss of a hair can take her into the land of the bald,
s/he will never become bald – even if, at some point, not a single
hair remains on her/his scalp.

Although this may seem, at first glance, to be an isolated puzzle,
only a  moment’s thought shows that vagueness is pervasive in our
everyday statements.  Among the predicates that have been discussed
in the  vagueness
literature : ‘chair’, ‘heap’, 'bald', 'thin', ‘obese’,
tall', 'tadpole',
'adult'.  In fact vagueness seems to affect virtually all predicates
that do not belong to mathematics.  Nor can sorites paradoxes be
dismissed as mere philosopher’s  puzzles.  For they seem to exhibit
a defect of our general accounts of correct inference. Yet few
philosophers are willing to throw out classical logic.  The
conviction remains that our understanding of classical logic, with
its use of idealized language and set theoretic interpretation,
tells us something about our vague natural language. How can
this be so?  How can our understanding of the workings of precise
languages be used to explain the contribution vague predicates make
to the truth-values of sentences in which they appear?

The literature on vagueness contains a number of proposals for
answering these questions. These proposals range from views on which
vague language requires a special sort of semantics to views on
which vagueness is not a feature of language at all. In this
course we will discuss the main proposals that appear in the
literature, including: epistemicism; supervaluationism, degree
theories and fuzzy logic, context based theories.

The central focus of this course will be a critical discussion of
these proposals. We will be particularly concerned to evaluate these
proposals in the light of how vague predicates function in the
current working sciences—and in particular the science that
as baldness and obesity in its purview, i.e., the science of
epidemiology.