Gaps, Gluts, and Truth

Project: Philosophy of Mathematics and Philosophy of Logic

University of Padua - Doctoral School in Philosophy (curriculum Theoretical Philosophy)

23 May 2013

FISPPA Department -- University of Padua

Workshop "Gaps, Gluts, and Truth"

10.30 - 11.40

Pablo Cobreros
Universidad de Navarra (Navarra, Spain)

Title: Symmetry, Gaps and Gluts

Abstract: Vagueness and the Liar paradox lead to a symmetry related situations that cannot be handled within classical semantics. In the case of vagueness, borderline cases lead to a symmetry of dispositions of competent speakers towards assertion and denial. In the case of the Liar, there is a symmetry in truth-value between the Liar sentence and its negation. Three-valued strong kleene semantics is a natural way to liberalize classical semantics. But then a second symmetry arises: should we read the intermediate value as a gap or as a glut?

11.45 - 12.55

Boris Rähme
Fondazione Bruno Kessler (Trento, Italy)

Title: An explanatory use of the concept of truth

Abstract: A central claim of deflationary accounts of truth for propositions is that truth talk has no explanatory role to play in philosophical elucidations of our epistemic and discursive practices. (An analogous claim is brought forward by disquotationalists, i.e. by proponents of deflationary accounts of truth for sentences. I will concentrate on deflationism about propositional truth.) In my talk I scrutinize the no-explanatory-role claim with respect to the following normative constraint on the speech act of assertion:

(N) It is correct to assert a proposition only if it is true.

Deflationists argue that the truth talk involved in (N) plays a purely generalizing role and justify this claim by pointing out that the content of particular instances of (N), say,

(T+) [It is correct to assert the proposition that some dogs are vicious] only if the proposition that some dogs are vicious is true.

can be expressed equally well without appeal to truth:

(T-) [It is correct to assert that some dogs are vicious] only if some dogs are vicious.

While conceding this last point to the deflationist, I argue that the particular ‘true’-free instances of (N) themselves stand in need of explanation and that the only candidate explanation in the offing is in terms of truth. The main thesis of my talk is, then, that the no-explanatory-role claim deprives deflationists about (propositional) truth of the resources to answer the following simple question: Why does (T-) hold good? After arguing that (T-) does indeed hold good, I discuss and dismiss several rejoinders that deflationists might level at my argument.

14.30 - 15.40

Martin Vacek
Slovak Academy of Sciences (Bratislava, Slovakia)

Title: Dialetheism and Metaphysics

Abstract: In the paper, I take logical laws to be entrenched in reality itself rather than in human conventions. Secondly, I discuss how such a robust realist conception of logical laws captures the logical complexity of concrete (possible and impossible) worlds. It will be shown that it is the structural properties of a world that
give us its logical laws. If so, the theory of concrete possible worlds instantiating various metaphysical structures enables us to non-modally differentiate between logically distinct worlds and, by the same reasoning, determines which worlds are impossible.

15.45 - 16.55

Sebastiano Moruzzi
University of Bologna (Bologna, Italy)

Title: Vagueness and Omniscience

Abstract: The paper explores the consequences of the notion of omniscience in relation to the problem of vagueness. Omniscience is an idealised notion: it is the condition according to which a thinker knows everything there is to know. 1 In the context of the debate on vagueness, omniscience can appear to be a loosely related topic. If we grant the logical possibility of a thinker who knows everything there is to know, an epistemicist might grant that vague boundaries would be known to such a thinker, while a theorist who believes vague predicates are boundaryless would hold that this latter knowledge is foreclosed even to an omniscient thinker. In this paper I will deal with the latter position, i.e. with the idea that vague predicates lack sharp boundaries.However, things are more complicated than what they appear to at first glance. Before drawing conclusions on this issue, the exact relation between indeterminacy, knowledge and omniscience must be clarified. I start introducing and motivating the relevance of omniscience to vagueness in relation to the supervaluationist approach. Two basic principles which relate vagueness to indeterminacy and knowledge are stated, and three definitions of omniscience are considered. I raise problems for all these definitions. Finally, I suggest that we are not in a position to know that omniscience is possible; we too easily come to accept the idea that omniscience is possible because of a misapprehension of the phenomenology of vagueness.

Organization: Massimiliano Carrara (University of Padua -- Cogito -
Research Centre in Philosophy) [email protected]