Paul Égré

Tolerant, Classical, Strict

In this paper we investigate a semantics for first-order logic originally proposed by R. van Rooij to account for the idea that vague predicates are tolerant, that is, for the principle that if x is P, then y should be P whenever y is similar enough to x. The semantics, which makes use of indifference relations to model similarity, rests on the interaction of three notions of truth: the classical notion, and two dual notions simultaneously defined in terms of it, which we call tolerant truth and strict truth. We characterize the space of consequence relations definable in terms of those and discuss the kind of solution this gives to the sorites paradox. We discuss some applications of the framework to the pragmatics and psycholinguistics of vague predicates, in particular regarding judgments about borderline cases.

Vagueness and Order Effects in Color Categorization

This paper proposes an experimental investigation of the use of vague predicates in dynamic sorites. We present the results of two studies in which subjects had to categorize colored squares at the borderline between two color categories (Green vs. Blue, Yellow vs. Orange). Our main aim was to probe for hysteresis in the ordered transitions between the respective colors, namely for the longer persistence of the initial category. Our main finding is a reverse phenomenon of enhanced contrast (i.e. negative hysteresis), present in two different tasks, a comparative task involving two color names, and a yes/no task involving a single color name, but not found in a corresponding color matching task. We propose an optimality-theoretic explanation of this effect in terms of the strict-tolerant framework of Cobreros et al. (J Philos Log 1–39, 2012), in which borderline cases are characterized in a dual manner in terms of overlap between tolerant extensions, and underlap between strict extensions.

Inexact Knowledge with Introspection

Standard Kripke models are inadequate to model situations of inexact knowledge with introspection, since positive and negative introspection force the relation of epistemic indiscernibility to be transitive and euclidean. Correlatively, Williamson’s margin for error semantics for inexact knowledge invalidates axioms 4 and 5. We present a new semantics for modal logic which is shown to be complete for K45, without constraining the accessibility relation to be transitive or euclidean. The semantics corresponds to a system of modular knowledge, in which iterated modalities and simple modalities are not on a par. We show how the semantics helps to solve Williamson’s luminosity paradox, and argue that it corresponds to an integrated model of perceptual and introspective knowledge that is psychologically more plausible than the one defended by Williamson. We formulate a generalized version of the semantics, called token semantics, in which modalities are iteration-sensitive up to degree n and insensitive beyond n. The multi-agent version of the semantics yields a resource-sensitive logic with implications for the representation of common knowledge in situations of bounded rationality.

Margin for error and the transparency of knowledge

In chapter 5 of Knowledge and its Limits, T. Williamson formulates an argument against the principle (KK) of epistemic transparency, or luminosity of knowledge, namely “that if one knows something, then one knows that one knows it”. Williamson’s argument proceeds by reductio: from the description of a situation of approximate knowledge, he shows that a contradiction can be derived on the basis of principle (KK) and additional epistemic principles that he claims are better grounded. One of them is a reflective form of the margin for error principle defended by Williamson in his account of knowledge. We argue that Williamson’s reductio rests on the inappropriate identification of distinct forms of knowledge. More specifically, an important distinction between perceptual knowledge and non-perceptual knowledge is wanting in his statement and analysis of the puzzle. We present an alternative account of this puzzle, based on a modular conception of knowledge: the (KK) principle and the margin for error principle can coexist, provided their domain of application is referred to the right sort of knowledge.

A uniform semantics for embedded interrogatives: an answer, not necessarily the answer

Our paper addresses the following question: Is there a general characterization, for all predicates P that take both declarative and interrogative complements (responsive predicates in the sense of Lahiri’s 2002 typology, see Lahiri, Questions and Answers in Embedded Contexts, OUP, 2002), of the meaning of the P-interrogative clause construction in terms of the meaning of the P-declarative clause construction? On our account, if P is a responsive predicate and Q a question embedded under P, then the meaning of ‘P + Q’ is, informally, “to be in the relation expressed by P to some potential complete answer to Q”. We show that this rule allows us to derive veridical and non-veridical readings of embedded questions, depending on whether the embedding verb is veridical or not, and provide novel empirical evidence supporting the generalization. We then enrich our basic proposal to account for the presuppositions induced by the embedding verbs, as well as for the generation of intermediate exhaustive readings of embedded questions (Klinedinst and Rothschild in Semant Pragmat 4:1–23, 2011).

Vagueness, Truth and Permissive Consequence

We say that a sentence A is a permissive consequence of a set of premises Γ whenever, if all the premises of Γ hold up to some standard, then A holds to some weaker standard. In this paper, we focus on a three-valued version of this notion, which we call strict-to-tolerant consequence, and discuss its fruitfulness toward a unified treatment of the paradoxes of vagueness and self-referential truth. For vagueness, st-consequence supports the principle of tolerance; for truth, it supports the requisit of transparency. Permissive consequence is non-transitive, however, but this feature is argued to be an essential component to the understanding of paradoxical reasoning in cases involving vagueness or self-reference.

Knowing whether A or B

The paper examines the logic and semantics of knowledge attributions of the form “s knows whether A or B”. We analyze these constructions in an epistemic logic with alternative questions, and propose an account of the context-sensitivity of the corresponding sentences and of their presuppositions.

Perceptual ambiguity and the sorites

The sorites paradox results from two equally plausible constraints on categorization in sorites series: a constraint of category switch between the first and the last items, and a constraint of similarity or consistent judgment for adjacent items. Following the work of D. Raffman [27,28] this paper argues that both constraints can be met if we assume that borderline cases pattern as ambiguous items between opposing categories. I first review some empirical evidence in favor of this view. I then examine how it bears on the tolerance principle, from a descriptive and from a normative viewpoint. In particular, I discuss ways in which the account of tolerance outlined in [6] can be related to Smiths [37] fuzzy account, as well as to the similarity-based semantics for vague predicates proposed by van Rooij [34] and explored in recent work with Cobreros et al. [4].

Tolerance and Mixed Consequence in the S'valuationist Setting

In a previous paper (see ‘Tolerant, Classical, Strict’, henceforth TCS) we investigated a semantic framework to deal with the idea that vague predicates are tolerant, namely that small changes do not affect the applicability of a vague predicate even if large changes do. Our approach there rests on two main ideas. First, given a classical extension of a predicate, we can define a strict and a tolerant extension depending on an indifference relation associated to that predicate. Second, we can use these notions of satisfaction to define mixed consequence relations that capture non-transitive tolerant reasoning. Although we gave some empirical motivation for the use of strict and tolerant extensions, making use of them commits us to the view that sentences of the form ‘