INSTITUT JEAN NICOD :
Stephen Schiffer, Professeur au département de philosophie de New York University, et Professeur invité à l’ENS (dans le cadre de la convention entre le Département de philosophie de l’ENS et celui de NYU), donnera une série de conférences à l’ENS sur le thème général « Vagueness » :
Mercredi 19 mars, de 10h à 12h, salle Beckett : The Sorites Paradox and Other Issues of Vagueness
Mercredi 26 mars, de 10h à 12h, salle Beckett : Semantic Theories of Vagueness : Epistemicism, Supervaluationism, and Many-Valued Theories
Mercredi 2 avril, de 10h à 12h, salle Beckett : Psychological Theories of Vagueness : Field, Schiffer, Wright
Jeudi 10 avril, de 10h30 à 12h30, salle des Résistants : Vagueness, Concepts, and Properties : a Non-Semantic and Non-Psychological Account of Vagueness
A correct account of vagueness is essential to the philosophy of language, for until we have one we won’t know the correct semantics and logic for vague language, and, since virtually all of natural language is vague, that means we won’t know the correct semantics and logic for natural language until we have a correct account of vagueness. After laying out the sorites paradox and other issues of vagueness, I critically examine the leading attempts to resolve those issues. Those attempts (including one to which I have contributed) are found wanting, and a new approach to resolving the problems of vagueness is proposed.
Lecture 1 : The Sorites Paradox and Other Issues of Vagueness
The sorites paradox is explained, and we see that to resolve it we’ll need an account of what vagueness is, and of the semantics and logic of vague language. Notice is taken of other prominent issues of vagueness : Is vagueness a feature of language and thought only, or is the world itself vague ? How are vagueness and indeterminacy related ? Can the identity relation be vague ? How are we to understand higher-order vagueness—borderline cases, borderline cases of borderline cases, borderline cases of borderline cases of borderline cases … ? How is vagueness affected by the context of utterance ? What kinds of expressions other than predicates can be vague ?
Lecture 2 : Semantic Theories of Vagueness : Epistemicism, Supervaluationism, and Many-Valued Theories
A semantic theory of vagueness is a theory that entails an account of the kinds of truth-values borderline statements can take. Epistemicism holds that borderline statements are either true or false ; supervaluationism holds that, although truth and falsity are the only truth-values, borderline statements are neither true nor false ; many-valued theories hold that borderline statements take truth-values other than truth or falsity—anywhere from three to as many of them as there are real numbers between 0 and 1. Each semantic theory has problems unique to itself, but one they all share is that they mispredict the psychological state that is characteristic of taking a statement to be borderline.
Lecture 3 : Psychological Theories of Vagueness : Field, Schiffer, Wright
A psychological theory of vagueness is a non-semantic theory that seeks to understand vagueness in terms of the psychological state that is characteristic of taking a proposition to be borderline. The theories of Field, Schiffer, and Wright each offer a different account of the nature of that state, of the way vagueness is to be explained in terms of that state, and of the way their accounts bear on the sorites paradox.
Lecture 4. Vagueness, Concepts, and Properties : a Non-Semantic and Non-Psychological Account of Vagueness
Taking a proposition to be borderline does typically manifest itself in a sui generis kind of mental state, but psychological theories of vagueness are mistaken in thinking that that kind of state is somehow constitutive of a proposition’s being borderline. For one thing, the psychological strategy leaves a puzzle about the nature of that feature of a vague property which makes something a borderline instance of it ; for another thing, it’s arguable that it’s merely a contingent fact about us that we respond as we do in taking a proposition to be borderline. A better strategy focuses not on the response of taking a proposition to be borderline but on (1) those features of our cognitive economy which are causally responsible for that response and (2) the role those features play in individuating the properties expressed by mentalese predicates. I suggest that this strategy, when conjoined with a certain view about the metaphysical nature of properties, yields a response-independent, but also non-semantic, account of that feature of a vague property which determines a thing to be a borderline instance it. This sort of account yields the same response to the sorites as my earlier psychological theory.