Zach Weber

University of Otago

At the Limits of Thought

26 February 2018, 16:30

Faculdade de Letras de Lisboa

Room 2.13

Abstract: The Inclosure Schema, proposed by Priest, suggests that many famous paradoxes are caused by the collision of “transcendence” and “closure” at the limits of thought. The Schema is, prima facie, a unified and explanatory analysis of the paradoxes of self-reference. Taking this analysis seriously is an important argument for dialetheism (the truth of some contradictions), and with that, a thoroughgoingly paraconsistent logic. But what happens once this program is followed out? That is, what happens when one re-considers the Inclosure Schema from a purely paraconsistent viewpoint? We will look at how the inclosure arguments play out. I will argue that the Inclosure Schema points outwards – too far outwards, beyond inconsistency and into absurdity. I will discuss how a reappraisal points inwards instead: true contradictions are better thought of as local, not “limit” phenomena. Dialetheism leads back from the edge of thought, to the inconsistent in the everyday.

Stewart Shapiro

Ohio State University

Making Truth Safe For Intuitionists
(joint work with Andrew Tedder)

21 February 2018, 16:00

Faculdade de Letras de Lisboa

Room 2.13

Abstract: We consider a handful of solutions to the liar paradox which admit a naive truth predicate and employ a non-classical logic, and which include a proposal for classical recapture. Classical recapture is essentially the property that the paradox solvent (in this case, the non-classical interpretation of the connectives) only affects the portion of the language not including the truth predicate – so that the connectives can be interpreted classically in sentences in which the truth predicate does not occur. We consider a variation on this theme where the logic to be recaptured is not classical but rather intuitionist logic, and consider the extent to which these handful of solutions to the liar admit of intuitionist recapture by sketching potential ways of altering their various methods for classical recapture to suit an intuitionist framework.

Graham Priest

City University of New York

Logic and Metaphysics: an Observation in Metametaphysics

26 February 2018, 14:30

Faculdade de Letras de Lisboa

Room 2.13

Abstract: In this talk I will demonstrate a connection between logic (qua theory) and metaphysics. A number of historical case studies show clearly that these two things are intimately entangled. I end by raising the single most important philosophical issue that this raises: which, if either, is the more fundamental?

Bruno Jacinto

LANCOG Universidade de Lisboa

Bridge Principles and Purely Epistemic Norms

17 January 2018, 16:00

Faculdade de Letras de Lisboa

Room Pedro Hispano

Abstract: One influential approach to inquiry on the normativity of logic consists in investigating what are the true bridge principles relating claims of logical consequence with norms for belief. Although the question of whether logic is normative is naturally understood as an epistemic one, bridge principles have typically been investigated in isolation from debates over the correct epistemic norms. In this paper we present a number of consequences for the normativity of logic of the hypothesis that logic is normative in a distinctively epistemic sense, and so that the norms occurring in bridge principles are epistemic norms. We do so by first proposing a Kripkean model theory accounting for the interaction between logical, doxastic, epistemic and deontic notions and then showing some of the predictions of the model theory concerning the implication of bridge principles by distinguished purely epistemic norms. The latter are norms, such as the truth and the knowledge norms of belief, whose formulation does not involve logical notions. They are formulated solely in terms of  doxastic, epistemic  and deontic notions. We conclude by proposing a minimal theory of the interaction between logical, doxastic, epistemic and deontic notions. The true bridge principles are at least those that are commitments of this minimal theory. [This is joint work with Claire Field]