The Theory of Relevance, Formal Fallacies of Relevance, and Relevant Logic

Nicholas Ferenz (Czech Academy of Science)

19 April 2024, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão [C201.J] (Departamento de Filosofia)

Abstract: Relevant logics are logics with a conditional connective that represents, in the object language, various sorts of entailment relations. These entailment or implications each necessitate restrictions on grounds of relevance. In Entailment vol. 1, Anderson and Belnap note certain (formal) fallacies of relevance that should not be theorems of any (propositional) relevant logic. The area of first-order relevant logics is comparatively underdeveloped both philosophically and mathematically. In this talk I develop an account of formal fallacies of relevance, drawing on the Sperber and Wilson’s Theory of Relevance in linguistics. In short, formulas that are formal fallacies of relevance require too much cognitive effort to establish relevance over every context with every instance of the formula. This account of formal fallacies of relevance have the advantages of (i) implying a core semantic property of relevance in propositional logics (namely the Variable Sharing Property), and (ii) divorcing the definition of relevance from that of (the) truth (values). I then turn to first-order logics, where I apply the framework to a selection of formulas and outline future goals.

The Hardness of the Practical Might

Sergio Tenenbaum (University of Toronto)

12 April 2024, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão [C201.J] (Departamento de Filosofia)

Abstract: Incommensurability is often introduced with the small improvement argument. Options A and B are shown to be incommensurable when it is neither the case that A is preferred to (or better than) B nor that B is preferred to (or better than) A, but a slightly improved version of A (A+) is still not preferred to B. Since A+ is preferred to A, but not to B, we must also conclude that it is also true that A and B are not indifferent (or equally good). Such incommensurable options seem incompatible with orthodox decision theory (and various forms of value theory) but options that obey the pattern described by this argument seem ubiquitous: my choice between lemon tarts and eclairs at my favourite pastry shop might exhibit this pattern, but so could my choice between jobs or careers. In trying to accommodate incommensurable options within various frameworks, philosophers have argued that we must preserve certain central features of the phenomenon. Among them is the supposed “hardness” of at least some incommensurable options: even if perhaps one would need to be a rather anxious gourmet to describe the choice between lemon tarts and eclairs as hard, the choice among careers could potentially be agonizing. However, it is not clear in which way choices among incommensurable options are “hard,” nor how and whether such hardness poses problems for the various accounts of incommensurable choices. To complicate matters, the deontic verdicts for choices between incommensurable options seem to be relatively straightforward: one appealing view is that in such circumstances I am rationally permitted to choose any option that is not worse than (or dispreferred to) another option. This paper aims to provide a sharper formulation of the hardness problem, to argue that various theories of incommensurability might fail to account for the hardness of some incommensurable choices, and to propose that the theory of instrumental rationality I develop in Rational Powers in Action, aided by a Kantian insight, promises to provide an adequate explanation of the hardness of choice among incommensurable options.

There Is No Such Thing as Conventionalism about Personal Identity

Eric Olson (University of Sheffield)

5 April 2024, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão [C201.J] (Departamento de Filosofia)

Abstract: It’s often said that personal identity is ‘conventional’ in that it depends on our attitudes and practices: it’s not a fact to be discovered, but a matter for decision. There are a number of different claims about ‘personal identity’ that are said to be conventional in this way. Some are intelligible but not actually conventionalism as advertised. Some are indeed conventionalist but unintelligible. Some are intelligible and conventionalist but not very interesting. But there appears to be no genuine conventionalism about personal identity that is both intelligible and interesting.

What Context-Relative Belief Could Be Like

Roger Clarke (Queen’s University Belfast)

22 March 2024, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão [C201.J] (Departamento de Filosofia)

Abstract: Several philosophers have recently defended metaphysically context-relative views of belief. But for many of us, it’s not clear what context-relativity could be if it isn’t semantic (or more broadly, linguistic) context-relativity. In this paper, I explore the idea of context-relative metaphysics through several examples, mostly taken from high-school science.

Disputed Disputes

Pedro Abreu & Marcin Lewiński (IFILNOVA, New University of Lisbon)

15 March 2024, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão [C201.J] (Departamento de Filosofia)

Abstract: Our goal is to isolate and analyse a category of “disputed disputes”: philosophically relevant disputes which do not admit of an easy dismissal as verbal nor of straightforward recognition as factual. We offer a new set of arguments challenging the attempts of adjudicating between these two possibilities. We pay special attention to how these attempts are articulated in the recent debates over metalinguistic negotiations — worthwhile disputes about which meaning to associate with some particular expression (Plunkett & Sundell, 2013, 2023). While Plunkett and Sundell hold metalinguistic negotiations to be “ubiquitous”, some recent criticisms maintain that many such disputes should be taken at face value as standard disagreements (Ball, 2020; Schroeter et al., 2022; Koslicki & Massin, 2023). Both positions are built on the underlying assumption that there is indeed a principled and operationalizable distinction to be made between two fundamentally different kinds of disputes. We challenge this assumption. Careful attention to the conditions of the debate reveals: i) unexpected congruence between the interpretative strategies and resources deployed by the two sides in the debate, ii) circularity and indeterminacy brought about by the possibility of applying the metalinguistic negotiation interpretation to the very disputes over the nature of disputed disputes, and, iii) the proliferation of available notions of meaning and corresponding forms of disagreement and verbalness. We show how these considerations coalesce to undermine the possibility of a principled choice between the two interpretations — metalinguistic negotiation and first-order disagreement — and to cast doubts on the claim that there is really a significant choice to be made between them.

Why do Computational Templates Work Across Scientific Disciplines?

Mariana Seabra (LanCog, Centre of Philosophy, University of Lisbon)

8 March 2024, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão [C201.J] (Departamento de Filosofia)

Abstract: Computational methods and their subsidiary models (including both physics-driven methods that appeal to differential equations, and data-driven computational methods that allow the extraction of meaningful patterns from data sets, often without explicit appeal to laws of nature or theories) are used to perform diagnosis, characterization and prediction in systems of interest. Furthermore, these computational methods are applied successfully across scientific disciplines, that is, the same computational structures, termed computational templates, are employed to solve problems in a wide range of scientific domains, from physics to biology, neurology, economics, and so forth. In this talk I try to explain the success of computational templates across different science fields, constructing a scientifically informed version of the ‘fudging solution’ for the applicability of mathematics as it arises for computational templates. I argue that the various templates available, from differential calculus to statistical models, capture change or changing tendencies in a system of interest. Corrections performed within the various stages of model construction not only concern updates in the formal structure of computational templates, but also progressively update the ontology of interest. What is perceived as the applicability of templates to physical reality is already the result of many such corrections, in which models are tailored to the system at hand.

Combinatory Intensional Logic: Towards a Formal Theory of Meaning

Clarence Lewis Protin (LanCog, Centre of Philosophy, University of Lisbon)

1 March 2024, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão [C201.J] (Departamento de Filosofia)

Abstract: In this talk we give an outline of Combinatory Intensional Logic (CIL), a general framework for a formal theory of natural language meaning and reasoning, including intensional logic. What sets this approach apart is a syntax close to the logico-semantic mechanisms of natural language and being compatible with logical realism, the view that properties, relations and propositions are entities in their own right as well as furnishing the senses of linguistic expressions. CIL models, which formalize a realm of interweavings of senses, are not based on possible world semantics or set-theoretic function spaces. Truth-values and references of senses are extensions determined by states-of-affairs, an idea that goes back to the Stoics. CIL was initially inspired by Bealer’s project in Quality and Concept (1983). It was subsequently found that CIL is a good tool to address the shortcomings and gaps present in Bealer’s approach, in particular with regards to the soundness proofs and the problem of unifying intensional and modal logic. After giving an outline of CIL and the main soundness result, we discuss approaches to classical problems involving definitions, definite descriptions, proper names and other topics relevant to the formalization of natural language.

Existence and Powers in a Dynamic World

Jonathan Tallant (University of Nottingham)

23 February 2024, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: In this talk I look to achieve two ends. The first is to offer some clarificatory and defensive remarks about what we think is required of existence in a genuinely dynamic world. In doing so, I lean on work focused on Existence Presentism, connecting that to work on powers. I suggest that this combination of literatures gives us the wherewithal to differentiate a frozen world, from a dynamic world, and in the process respond to challenges that have been raised for presentism. The talk begins with consideration of the notion of dynamism, drawing out the idea of degrees of dynamism and offering an account of what it takes to make a view more (or less) dynamic. In the second part of the talk I explore how to generate dynamism given recent arguments from Lisa Leininger.

Delusions and the Predictive Mind

Federico Bongiorno (LanCog, Centre of Philosophy, University of Lisbon)

16 February 2024, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: A growing number of studies in both the scientific and the philosophical literature have drawn on a promising framework of brain function (predictive processing) to account for the formation of delusions. This framework has recently come under criticism for its putative inability to explain (i) why agents adopt implausible hypotheses like delusions over none at all, or over more plausible ones, and (ii) how exactly it is that delusions are thought of to begin with. In this talk I shall defend the framework’s explanatory power by way of showing how it can go a long way in helping disentangle these concerns.

Beyond Juxtaposition: Mixed Inferences and Anti-Collapse

Carlos Benito-Monsalvo (LanCog, Centre of Philosophy, University of Lisbon)

15 December 2023, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: Logical localism is a thesis within philosophy of logic according to which the correct application of logic is not topic-neutral, domain-neutral or irrespective of subject-matter. That is, logical localism is the thesis stating that different sets of logical principles, forming various alternative logic systems, are required in order to systematically account for correct reasoning in different domains. However, there is a very straightforward problem for anyone defending a localist thesis, a problem that follows from the fact that we reason across domains. This challenge is known as the problem of mixed inferences. The problem is, very roughly, the following: suppose that there are (at least) two components, within the premises or conclusion of an argument, belonging to different domains whose logics are L₁ and L₂, respectively. Then, which is the criterion of validity for the argument? The approach that I will take consists in trying to solve the problem of mixed inferences (more concretely, the version of the problem raised by Chase Wrenn) by making a finer translation of the arguments and using combination mechanisms as the criterion of validity. Among the alternative methods for combining logics, I will focus on the method of juxtaposition and show that there are some mixed inferences with the logical form of bridge principles that seem to be intuitively valid and that are not validated by juxtaposition, which constitutes an anti-collapse problem for juxtaposition. This limitation is what motivates the improvements on the methods that I propose, as a way of extending juxtaposition and allowing the emergence of the justified bridge principles in the combination mechanisms.