Ricardo Santos

Universidade de Lisboa

The Fitch-Church Argument, the Knower Paradox and Paraconsistency

21 July 2017, 16:00

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: We surely do not know everything, but some philosophers have thought that every truth can be known – by following the right method (be it the Cartesian method, or ‘the’ scientific method). An interesting argument first published by Frederic Fitch, but most likely due to Alonzo Church, purports to show that those philosophers are wrong, and that there are necessary limits to what can be known by non-omniscient beings like us. For many people of a more realist persuasion, that there are unknowable truths is good news, so they tend to look favorably to the Fitch-Church argument. But the argument looks suspicious, because it performs a kind of modal collapse, allegedly showing that if every truth is knowable, then every truth is known – so it invites looking for ways to resist it. In this talk, I will examine one way in which the Fitch-Church argument may be blocked, namely by adopting a paraconsistent logic and a dialetheic view of knowledge, independently motivated by another important problem, the Knower Paradox (due to Richard Montague). The dialetheic approach to both problems faces some objections, which I will discuss. I will argue that dialetheism proves better as a solution to the Knower than as a solution to the more general knowability problem.

Free Attendance

For further information, please contact CFUL at c.filosofia@letras.ulisboa.pt

A revista de filosofia DisputatioInternational Journal of Philosophy, publicada pelo Centro de Filosofia da Universidade de Lisboa, foi avaliada com a categoria Q2 pelo terceiro ano consecutivo no ranking SCImago/Scopus, o que faz com que ela seja actualmente a revista de Filosofia publicada num país iberoamericano em melhor posição naquele ranking. Conferir:


Alyssa Ney

UC Davis

Physics and Fundamentality

14 July 2017, 16:00

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: What justifies the allocation of funding to research in physics when many would argue research in the life and social sciences may have more immediate impact in transforming our world for the better? Many of the justifications for such spending depend on the claim that physics enjoys a kind of special status vis-a-vis the other sciences, that physics or at least some branches of physics exhibit a form of fundamentality. The goal of this paper is to articulate a conception of fundamentality that can support such justifications. I argue that traditional conceptions of fundamentality in terms of dynamical or ontic completeness rest on mistaken assumptions about the nature and scope of physical explanations.

Centro de Filosofia da Universidade de Lisboa

LanCog Group (Language, Mind and Cognition Research Group)


Centro de Filosofia das Ciências da Universidade de Lisboa


Alexander Carruth

Durham University

Being Physical

7 July 2017, 16:00

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: In order for certain debates in the philosophy of mind to proceed in good order—especially those concerning the relationship between mind and body—there are certain desiderata that any characterisation of the notion of ‘physical’ ought to meet. Our understanding of what it is for something to be physical ought not, for instance, to render the doctrine of physicalism either obviously false or trivially true—and much has been said about these desiderata in discussions concerning Hempel’s dilemma. It is also sometimes, although not always, suggested that there ought to be an empirical component to the truth of physicalism—our notion of what it is for something to be physical should render it conceivable that empirical evidence could come to light which falsifies physicalism. In this talk it will be argued that another, less discussed, desideratum for a satisfying characterisation of the physical is that it ought to be able to distinguish physicalism not just from dualism, but from alternative, non-physicalist monisms such as idealism, phenomenalism, panpsychism and neutral monism. To set the scene, the problem that Hempel’s dilemma raises for simple science-based accounts of the physical will be outlined. Two recently popular accounts of the physical, the via negativa account and object-physicalism, however, can avoid such problems. But these two accounts, it will be shown, fail to meet the fourth desideratum—they cannot distinguish phsyicalism from other forms of monism.

Ofra Magidor

University of Oxford

Co-predication and Property Inheritance
(co-authored with David Liebesman)

30 June 2017, 16:00

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: It is tempting to think that words like ‘book’ are ambiguous between a ‘physical book’ sense and an ‘informational book’ sense: on the physical sense, three copies of War and Peace count as three books, and on the informational sense, as only one book. However, this ambiguity hypothesis seems to face problems with cases of co-predication, namely sentences such as ‘Three red books are informative’. The problem arises from the claims that: (i) ‘red’ only applies to physical books; (ii) ‘informative’ only applies to informational books; and (iii) we have only one occurrence of the word ‘book’ in the sentence.

Co-predication has been taken in the literature to be a deep problem that forces us into radical conclusions, most notably, the abandonment of referential semantics altogether. In this paper we argue that no such radical conclusions are warranted. We offer a novel account of co-predication which denies both that ‘book’ is ambiguous, and that there are strong categorical restrictions preventing physical books from being informative, or informational books from being red. We show how our account can address a wide variety of cases of co-predication and deal with some objections.

Eduardo Castro

Universidade da Beira Interior

Induction and Broken Necessities

23 June 2017, 16:00

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: In a forthcoming paper, ‘Induction and Natural Necessities’, Stathis Psillos tries to refute the necessitarian solution to the problem of induction provided by David Armstrong. To accomplish this desideratum, he proposes that the best explanation for our observed regularities is a sort of ‘best before date’ necessity. That is, necessary connections may break down and they are not by default timeless. He develops arguments against my defence of the necessitarian solution accomplished in ‘On induction: time-limited necessity vs. timeless necessity’. Namely, he alleges that his proposal does not imply any further inductive generalization to Armstrong’s timeless necessity and it continues to establish new inferences regarding the unobserved. In this talk, I provide replies to Psillos’ proposal.

Ben Bradley

Syracuse University

Resonance and Modality

16 June 2017, 16:00

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: Subjectivist theories of welfare are largely motivated by a resonance constraint. Roughly, the resonance constraint holds that nothing can be good for someone unless it resonates with them. This general statement of the resonance constraint leaves important questions unanswered. One question involves modality. What does the resonance constraint entail about cases where something resonates with me at one possible world but not another? This is closely related to a second, more widely discussed question: what happens when something resonates with a person at one time but not another? I discuss some different ways we might formulate a resonance constraint. They are importantly different and lead to different results in interesting cases.