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03/06 - Pedro Carrasqueira

On the foundations of a theory of deliberative reason: A logical survey of the general principles of the theory of rational choices and coherent preferences

Last century witnessed a great development of the mathematical foundations of social sciences, due to the rapid growth of research in decision theory, game theory and social choice theory and to the astounding results obtained in those fields. Such studies seem to me to point towards a more general theory of rationality in practical contexts, and, in particular, to a mathematical theory of deliberative reason. Such a possibility, however, presupposes a (to the best of my knowledge) not yet systematically undertaken philosophical inquiry of the principles underlying those theories, --- one that would explore their pertinence to settings broader than those proper to the social sciences.

My exposition shall be divided in three parts.

In the first part I shall present the main concepts common to all those theories --- to wit, the notions of choicepreferencewelfare, norm and strategy --- and discuss in very broad strokes how they relate, with special attention to the relation between the more fundamental concepts of choice and preference. (I say they are more fundamental because they seem to me to be the ones that characterize, minimally, a deliberative setting.)

In the second part I shall briefly discuss what contributions (beyond the already well-known use of games in model theory) I believe such an enlargement of the field of application of those concepts would have to offer to logic in general, and to logic in practical contexts in particular.

In the third part I shall present a few questions about how already well-established logic, and modal logic in particular, could contribute to the understanding of those fundamental concepts of deliberative reason. I shall also present, if time allows it, some still very sketchy proposals of mine towards such a contribution.


Colloquium Logicae: Prof. Stefano Predelli

Meaning Without Truth

Stefano Predelli (da Universidade de Nottingham) apresentará as principais ideias e resultados de seu recente livro "Meaning Without Truth" (Oxford UP 2013). Trata-se de uma interessante tentativa de tratar de forma rigorosa e sistemática aspectos do significado que não são capturáveis na semântica verifuncional (estendendo de algumas formas relevantes a semântica de Kaplan em termos de caráter e conteúdo). Teremos também como comentadora Eleonora Orlando (da Universidad de Buenos Aires).

Três sessões. Sala Kurt Gödel, CLE-UNICAMP.
25 de maio (segunda-feira), 16h: Meaning Without Truth I
27 de maio (quarta-feira), 16h: Meaning Without Truth II
3 de junho (quarta-feira), 14h: Meaning Without Truth III


06/05 - Marco Ruffino

A Puzzle About Frege’s Singular Senses

In this paper I discuss what seems to be a puzzle for Frege’s notion of singular senses (i.e., the senses of singular terms) assuming the interpretation that, for him, every singular term is reducible to (or express the same sense as) some definite description. Singular senses are supposed to be complete (or saturated), but they are composed of the incomplete (unsaturated) senses of the concept-words of the descriptions. I ask how the definite article (or what it expresses) “transforms” an unsaturated sense into a saturated one, and review some attempted explanations in the literature. I argue that none of them is compatible with Frege’s broader views in semantics. Next I discuss one alternative that Frege himself endorses (the definite article indicating an attitude on the speaker’s part). This alternative, I argue, is also incompatible with his semantics. I conclude that Frege has no coherent view on singular senses.



Colloquium Logicae: Prof. Dr. Wolfgang Lenzen

"Leibniz Logic" on Wednesday April 15th, 16:30, Gödel Room at CLE- UNICAMP

"A Survey on Epistemic Logic" on Thursday 16th, 14:00, Gödel Room at CLE- UNICAMP

Biography and eulogy: Prof. Wolfgang Lenzen (in German)

Department of Philosophy, Universität Osnabrück, Germany


25/03 - Lucas Rosenblatt (Colloquium Logicae)

Capturing Naive Validity in the Strict-Tolerant Approach

Rejecting the structural rule of Cut has been recently proposed as a strategy to avoid both the usual semantic paradoxes and the so-called Validity Paradox. In this paper we consider if a theory that rejects Cut is capable of accurately representing its own notion of validity. We claim that the standard rules governing a naive validity predicate are too weak for this purpose and we show that although it is possible to strengthen these rules, the most obvious way of doing so brings with it a serious problem: an internalized version of Cut can be proved. We also evaluate a number of possible ways of escaping this difficulty.


11/03 - Emiliano Boccardi

If it ain’t Moving it shall not be Moved: real passage for A-theorists

Imagine two friends sitting on a beach, looking at a ship far away. Because of the distance, they cannot just tell by looking at it whether the ship is moving or not. “I bet it’s moving” says one. “No it’s not!”, says the other. Do they disagree about something? And if yes, what is the disagreement exactly about?

After some time the two friends look again and the ship has obviously moved, although it looks to them just as still as it looked before: its position (relative to them) has changed. “Aha!”, says the first, “I told you it was moving!” “You were right, it was moving. I lost the bet!”, says the other. What was this bet about?

Physics and mathematics  textbooks  follow  Bertrand  Russell  in accounting  for  a  body‘s instantaneous velocity not merely as equal to, but moreover as identical to the time-derivative of its trajectory. On this view, a body’s instantaneous velocity is ontologically parasitic on its trajectory. This deflationist understanding of change was heavily inspired by Weierstrass’ and Cantor’s understanding of limit and infinity. According to Weierstrass’ conception of limits and infinitesimals (now the received view), variables are just denotational schemas: they contribute to the sole purpose of denoting large numbers of (unchanging) facts about their values. The values of the variables do not themselves vary: they do not “approach”, let alone “reach” their limits, or change in any sense, contrary to what they were ambiguously alleged to be doing in prior formulations (since Newton’s and Leibniz’s). Of course, according to this conception, neither do variables themselves vary or change, in spite of their evocative name. It was this reconceptualization of the notion of limit that inspired Russell’s treatment of the antinomies involved in the notion of indefinitely growing series of things (such as those involved in Zeno’s paradoxes): “Weierstrass”, he says, “by strictly banishing all infinitesimals has at last shown that we live in an unchanging world, and that [Zeno’s] arrow, at every moment of its flight, is truly at rest” (POM, p. 347).

Likewise, many philosophers of time argue that the passage of time is identical with the fact that different times subsequently instantiate presentness.

However, I shall argue in the first part of this talk, it is tempting to think that the initial disagreement between the two friends is about a property instantiated by the ship at (and only at) the time of the bet (t1). What they observe at the time of the assessment of the bet (t2), according to this intuitive view, is the comparative fact that the ship’s location at t1 is different from its location at t2. They agree that this provides indirect evidence for the further (non-comparative) fact that the ship was moving at t1. If the ship is found at different positions at times right after t1, this must be because at t1 it possessed an intrinsic kinematic quantity in addition to its position.

If this explanatory pattern is sound, then the comparative fact that (a) the location of the ship at t1 is different from its location at t2, must be ontologically distinct from the (non-comparative) fact that (b) the object has been in motion for enough times between t1 and t2. In short, according to this view, the displacement of the ship is a posthumous consequence of its state of motion (velocity) throughout the time interval considered, hence fact b (the explanans) cannot be identical to fact a (the explanandum). Analogously, I shall defend the thesis that yesterday became past because time passes. The passage of time ought to explain the ensuing comparative fact that Today’s presentness followed Yesterday’s presentness, so it cannot be thought of as identical with it. The ensuing view construes passage as an intrinsic, non-comparative feature of time instants.

In the second, more tentative part of the talk, I shall bring this issue to bear on the formal semantics of axiomatic treatments of aspect. In particular, I shall consider different solutions to the so called Imperfective Paradox, and test them against the desiderata put forward in the first part of the talk.


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