Cognitive Origins of Vagueness – Vagueness

Predicates of natural language like 'red', 'rich' or 'young' are vague, in the sense that they have borderline cases: for instance, we readily admit that an 18 year old is young, and that a 90 year old is not young, but it seems hardly possible to specify the precise age at which an individual would cease to be young. The phenomenon of vagueness has given rise to a large body of literature since the 1970s, in the domains of philosophical logic, cognitive psychology and natural language semantics. While most of the literature in philosophical logic deals with the semantic resolution of sorites paradoxes induced by vague predicates, increasing attention has been given in recent years to the sources of vagueness, both semantic and epistemological. Is vagueness due fundamentally to our ignorance of the limits of applicability of natural language predicates, as argued by proponents of the epistemic account of vagueness (Williamson, Sorensen)? Or rather, does vagueness fundamentally originate in the fact that some stimuli are ambiguous and that this ambiguity cannot be resolved on purely objective grounds, as suggested by the semantic and contextualist accounts of vagueness (Raffman, Shapiro)? The project aims at settling the debate, by investigating the cognitive origins of vagueness into more detail. While the project is led by philosophers and is mostly theoretical, one ambition of the project will be to promote new perspectives on the problem of vagueness, giving in particular emphasis to psychological aspects of the problem in semantics and in perception, but also to foundational issues in the epistemology of vagueness more generally. The project will be led by philosophers with complementary interests and backgrounds, competent in the areas of philosophy of science (Anouk Barberousse), philosophy of language (Pascal Ludwig, Paul Egré), philosophy of mind and perception (Jérôme Dokic, Pascal Ludwig) psychology (Jérôme Sackur), and formal semantics and philosophical logic (Denis Bonnay, Paul Egré). The project is articulated on the investigation of 5 main issues: (1) What is the link between vagueness, context-dependence, and ambiguity? This part of the project will rely on the semantic literature of vagueness. We will discuss work on the typology of vague predicates and on the different forms of context-dependence at stake in the phenomenon of vagueness. (2) How is vagueness semantically and perceptually resolved? Our perception of phonemes is essentially categorical, leaving little room for ambiguity, even when stimuli are made to vary continuously. The project will discuss the scope of categorical perception, and examine the relative status of semantic indeterminacy. Experiments will be made to see how subjects actually behave in situation of forced semantic choice in front of soritical series. (3) What is the scope of judgments of uncertainty characteristic of vagueness? Vagueness in the epistemic account of vagueness is referred to the non-transitivity of perceptual indiscriminability. Williamson's logic of inexact knowledge, in particular, makes crucial use of the intransivity of indiscriminability to model higher-order vagueness. Experiments will be made to test for higher-order uncertainty in semantic judgments, in particular to delimit the scope of higher-order vagueness in a more precise way. (4) What are the epistemological foundations of fuzzy-logic and degree-theoretic treatments of vagueness? This part of the project will rely on the historical and critical assessment of the probabilistic account of vagueness put forward by Emile Borel in the beginning of the 20th century. We propose to clarify the foundation of the notion of degree of truth on the basis of Borel's account, as well as the articulation between modern fuzzy logic and probability theory. (5) What is the incidence of vagueness in decision-theory? Vagueness is not only manifest in explicit linguistic judgments, but is implicit in scenarios in which subjects have to make practical decisions that depend on their implicit estimation of how large or small a quantity is. An instance of this problem is the characterization of 'almost common knowledge' in situations of mutual uncertainty. Decision-theoretic aspects of the phenomenon of vagueness will be investigated. The research will rely on the continuation of work and collaborations in progress on each of these issues. The project relies on the association of members of the Logos group in Barcelona (Prof. M. Kölbel and M. Garcia-Carpintero in particular). It involves the organization of several international conferences and its aim is to foster collaboration with groups active on this topic in other places in Europe in particular (Oxford, St Andrews, Prague).