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]

Guido Imaguire

Federal University of Rio de Janeiro

A Semantic Criterion for Existential Import

19 December 2017, 16:00

Faculdade de Letras de Lisboa

Room B1

Abstract: In his book Logic and How It Gets That Way, Jacquette (2010) presents ‘the formalization paradox’ which emerges from the attempt to formalize a sentence like ‘Some monkey devours every craisin’, where craisins are imaginary non-existent fruits. From this paradox Jacquette concludes the expressive inadequacy of classical predicate quantificational logic. In this paper I analyze the three assumptions made in the emergence of the paradox, viz.: (i) colloquial expressions of the same logical form can and should be formally symbolized by applying the same symbolization schema; (ii) ‘Some monkey devours every raisin’ is correctly translated as ∃x (Mx ∧ ∀y (Ry ® Dxy)); (iii) uninstantiated predicates can legitimately enter into (meaningful, true or false) predicate-quantificational symbolizations. I fully accept (iii), but reject both (i) and (ii).  I argue, firstly, that (i) has at first glance two possible interpretations, one trivial and one false. So, I try to establish a third and more reasonable interpretation. Based on this interpretation I argue that ∃x (Mx ∧ ∀y (Ry ® Dxy)) is not the adequate formalization of ‘Some monkey devours every raisin’. My basic claim is based on a generalization of Russell’s theory of descriptions: just as most sentences of natural language which contain definite descriptions are viewed as entailing existential force which must be made explicit in formalization, so do we also consider many, although not all, sentences which contain general terms. A criterion will be presented and defended for deciding in each possible case if a sentence entails existential force.

Guido Imaguire

Federal University of Rio de Janeiro

Is Ostrich Nominalism a Dismissive Solution
to the Problem of Universals?

15 December 2017, 16:00

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: Ostrich Nominalism is often described as a dismissive solution to the problem of universals. This is curious because there is no agreement about what exactly is the core of this problem, and which is its adequate formulation. In this paper I will present five different formulations and argue that Ostrich Nominalism is not dismissive at all. In fact, I will propose a positive and substantial answer to each one of the formulations of the problem. However, in order to solve predicaments of the original formulation of Ostrich Nominalism it will be important to appeal to the notion of ontological grounding and its logic.

Luís Estevinha Rodrigues

Federal University of Ceará

Mixed Epistemology, Methodological Naturalism, Gettierization and Explanatory Blindness

24 November 2017, 16:00

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: Henderson & Horgan (2011) defended a middle ground epistemology with three main ingredients: low-grade apriorism, transglobal reliabilism and objective epistemic justification. In this talk I evaluate the bulk of this proposal and raise some objections concerning the scope of its naturalized chunk.

Filipe Martone

University of Campinas / FAPESP

Against Sentential and Propositional Priority in Metasemantics

17 November 2017, 16:00

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: In virtue of what do our words have meaning? It is nearly a truism that words have meaning because they are connected with human actions: we endow them with significance in virtue of using them to engage with the world. Sentence Priority is the thesis that the fundamental language-world engagement occurs at the level of whole sentences. It follows that sentences, not words, are the fundamental bearers of meaning. The motivation behind Sentence Priority is what I call Propositional Priority, the idea that propositional speech acts (things like asserting and commanding) are the most fundamental linguistic actions out of which meaning emerges. In this talk I argue that those theses cannot be right. I show that, if we accept Propositional Priority, we must accept Sentence Priority. However, Sentence Priority leads to the indeterminacy of word meaning, and this makes it impossible to explain how unused sentences have the meanings that they do. In short, Propositional and Sentence Priority are incompatible with compositionality, or so I claim. I argue that there must be at least some fundamental language-world connections at the subsentential level that explain how word meaning can directly emerge. I conclude by sketching a broadly Russellian account.

Massimiliano Carrara

University of Padua

Denial: a Logic, a Paradox and a Dilemma

10 November 2017, 16:00

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: How glut-theorists may express disagreement with the assertion of A if Boolean negation cannot be expressed in their language? A glut-theorist’s answer is by denying or rejecting A: To make up for the lack of exclusive negation, a glut-theorist like Priest introduces the notion of denial or rejection of a sentence, understood as a speech act, as clearly distinguished from the acceptance of the negation of A. I argue that the proposal meets some difficulties: the reason is that if the exclusivity of negation is the key to solving the semantic paradoxes, the exclusivity of denial/rejection land us back in paradox. I sketch a bilateral logic of exclusive denial for glut theorists – an extension of the Logic of Paradox (LP) and I observe that exclusive deniability – a key semantic notion of the logic – is not expressible in a dialetheist’s language. I conclude that glut theorists are faced with a dilemma: either denial can serve as means to express disagreement, but the notion of exclusive deniability is not expressible in the glut theorist’s language, or deniability is expressible, but denial may no longer serve as a means to express disagreement.

Bogdan Dicher

LANCOG Universidade de Lisboa

The Original Sin of Proof-Theoretic Semantics
(joint work with Francesco Paoli)

3 November 2017, 16:00

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: Logical inferentialists hold that the meaning of the logical constants is determined by the rules of inference which govern their behaviour in proofs. In the inferentialist tradition, one usually identifies the derivability relation of a logic with the logic’s (internal) consequence relation. This leads to departures from the orthodox Tarskian view according to which a consequence relation is reflexive, monotonic, and transitive. Our aim is to show that the inferentialist account of the meaning of the logical constants can keep very close to the Tarskian paradigm. Using the Blok-Jonsson theory of abstract consequence relations, we show how meanings can be seen to be determined inferentialistically within the bounds of a reflexive, monotonic and transitive consequence relation.