Project description

The ANR program "Cognitive Origins of Vagueness" (ANR-07-JCJC-0070), funded by the Agence Nationale de la Recherche, is directed by Paul Egré and based at Institut Jean-Nicod in Paris. The project has officially started in January 2008.

Vagueness concerns the problem of specifying the limits of applicability of our linguistic and perceptual categories. Mathematical concepts such as "prime number" or "acute angle" have a precise extension in principle, but it is not so for everyday concepts such as "red", "tall", "heap" or "house". These concepts are often flexible in that they are applicable to objects that look quite dissimilar from each other upon closer examination. More fundamentally, vague concepts admit borderline cases, namely cases for which we are uncertain as to whether the concept should apply or not (for instance, where is the limit between dark blue and light blue in the columns surrounding this text? is the color you perceive really blue, or grey or green?). In relation to this, vague predicates also typically give rise to logical puzzle or paradox (such as the sorites paradox, according to which if x and y are only slightly different in respects of how tall they look, then x and y should either both be tall, or both be not-tall).

The literature on vagueness has been florishing since the 1970s, but the present project was inspired mostly by philosophical debates that have taken place since the 1990s, surrounding the epistemic conception of
vagueness notably defended by R. Sorensen and T. Williamson. On the epistemic view, vague concepts are assumed to have sharp boundaries, but those limits are essentially unknowable, due to our limited powers of perceptual and conceptual discrimination. A welcome consequence of the epistemic conception is that the logic of vague concepts can be kept bivalent and simple. In this, the epistemic conception of vagueness distinguishes itself from alternative frameworks, such as fuzzy logics, supervaluationism, or many-valued approaches more generally. Another virtue of the theory concerns the emphasis put by Williamson on models of imperfect discrimination, in particular in the attempt to derive vagueness from non-transitivity in discrimination. A drawback, on the other hand, is that the epistemic view postulates the existence of sharp boundaries where our concepts may really be boundariless (Sainsbury), or having essentially blurry boundaries, and where the origin of vagueness proper may be semantic and more fundamentally rooted in language and categorization than in our limited capacity to perform fine-grained discriminations.

As the title indicates, the main aim of the project is to investigate the issue of the cognitive sources of vagueness, in particular to adjudicate whether and how much vagueness originates in imperfect discrimination proper, rather than from other sources. The view of vagueness as imperfect discrimination brings vagueness close to imprecision or inexactness,
but several alternatives to that view are conceivable and are worth exploring. From a cognitive perspective, vagueness may also be seen as more intrinsically connected to ambiguity in perception and categorization (Raffman), or as resulting from underspecification in language (gap theories, cf. Lewis, Kamp, Fine). Or, at the opposite, it could be the result of an overlap or friction between adjacent categories (glut theories, viz. Hyde). Even more deeply, it may well be tied to grading and gradedness as a fundamental property of  most properties (fuzzy approaches, viz. also N.Smith's work).

The present project aims at exploring new and interdisciplinary approaches concerning the sources of vagueness, in particular through collaborative meetings involving not only philosophers, but also linguists, psychologists and decision theorists. A substantial part of the project so far has been devoted to the examination of the link between logical and psychological models of imperfect discrimination and non-transitivity (such as signal detection theory, in particular in relation to Williamson's margin for error models)
. More recently, collaborations have taken place to reassess the link between vagueness and ambiguity (cf. Raffman), to relate vagueness to psychological models of similarity in categorization (Gärdenfors), to connect semantic and psychological models of comparison with the logic of vagueness (Goodman, Luce, van Rooij), in particular to explore alternatives to classical logic in relation to vagueness. 


  • Core members of the project in Paris besides P. Egré include A. Barberousse (IHPST), D. Bonnay (DEC, Nanterre), J. Dokic (IJN-EHESS), P. Ludwig (Paris IV), J. Sackur (LSCP).  Several members of IJN and DEC-ENS have regularly participated in the seminar since 2008 (including D. Nicolas, E. Chemla, F. Corblin, F. Récanati, I. Stojanovic,...)
  • Two postdoc researchers have been hired on the project since 2009: Mikaël Cozic (march-august 2009) who worked on vagueness and decision theory, and David Ripley (2009-2010), presently working on vagueness and contradictions. V. de Gardelle (Oxford) is also collaborating with us on an experimental project. In 2010 and 2011, Julien Boyer (PhD) has been hired as an assistant in the project.
  • PhD, master's students and visitors temporarily involved in the project: Will Davies (Oxford), Thomas Charreau (IJN). Ariadna Fernandez (DEC-ENS).
  • Collaborations have taken place between P. Egré and other teams active on vagueness in Europe, including with N. Klinedinst (UCL Linguistics), with I. Douven (Leuven), R. Dietz (Leuven) and L. Decock (UvA, Amsterdam), with P. Cobreros (Navarra), D. Ripley (now in Melbourne) and R. van Rooij (ILLC Amsterdam), and with James Hampton (London/NYU).


Four conferences or workshops have been organized in Paris since 2008:


  • Seminar and reading group in 2008
  • Seminar and reading group in 2008-9
  • Seminar and reading group in 2009-10


  • Pablo Cobreros, Paul Egré, David Ripley and Robert van Rooij will teach a joint course on Non-classical logics for vague predicates in ESSLLI 2011 in Ljubljana.
  • Introduction to the semantics and epistemology of vagueness, course given by P. Egré at ENS in 2009, 2010 and 2011
  • Course by P. Egré at the Ateliers de sémantique et modélisation, Nancy, 2010


Main publications in relation to the Project:


  • P. Egré and N. Klinedinst (eds.) (2011). Vagueness and Language Use, Palgrave Mc Millan, Studies in Pragmatics, Language and Cognition (with contributions by C. Barker, P. Cobreros, D. Fara, L. Wolf and A. Cohen, S. Fults, C. Kennedy, R. Nouwen, P. Pagin, G. Sassoon, R. van Rooij, U. Sauerland and P. Stateva, P. Sweeney and E. Zardini).
  • I. Douven, L. Decock, R. Dietz, P. Egré (under review), Vagueness: a Conceptual Spaces Approach.
  • P. Cobreros, P. Egré, D. Ripley, R. van Rooij (2011), Tolerant, Classical, Strict, Journal of Philosophical Logic.
  • D. Ripley (2011), Contradictions at the Borders, in R. Nouwen, R. van Rooij and H-C. Schmitz (eds), Vagueness in Communication, LNAI, Springer.
  • D. Bonnay and P. Egré (2011), "Knowing one's limits - An analysis in Centered Dynamic Epistemic Logic", in P. Girard, M. Marion and O. Roy (eds), Dynamic Formal Epistemology, Springer.
  • D. Ripley (2011), Sorting out the Sorites, in F. Berto and E. Mares and K. Tanaka, Paraconsistency: Logic and applications, Springer (Logic, Epistemology, and Unity of Science series).
  • P. Egré (2011), Perceptual Ambiguity and the Sorites in R. Nouwen, R. van Rooij and H-C. Schmitz (eds), Vagueness in Communication, LNAI, Springer.
  • P. Egré (2011), Review of N. J. Smith's "Vagueness and Degrees of Truth", Australasian Journal of Philosophy.
  • P. Egré (2010), Qualitative Judgments, Quantitative Judgments and Norm-Sensitivity, Behavioral and Brains Sciences, 33 (4), pp. 335-336.
  • J. Dokic and P. Egré (2010). L'identité des qualia et le critère de Goodman. In J. Morizot et J-B. Rauzy (eds.), volume à paraître sur la Structure de l'Apparence de N. Goodman, Vrin.
  • P. Egré and D. Bonnay (2010). Vagueness, Uncertainty and Degrees of Clarity. Synthese
  • D. Bonnay and P. Egré (2009). Inexact Knowledge with Introspection. Journal of Philosophical Logic, 38 (2), pp. 179-228.
  • P. Egré (2009), Soritical Series and Fisher Series, in H. Leitgeb and A. Hieke eds., Reduction. Between the Mind and the Brain, pp. 91-115, Ontos-Verlag
  • J. Dokic and P. Egré (2009). Margin for Error and the Transparency of Knowledge. Synthese.
  • D. Bonnay and P. Egré (2008). Margins for Error in Context, in M. Garcia-Carpintero and M. Kölbel (eds.), Relative Truth, pp. 103-127, Oxford University Press