Francois Lepage

This paper presents a generalization of a proposal of van Benthem’s who has shown how to provide a canonical name for any object in propositional type theory. Van Benthem’s idea is to characterize any function in the hierarchy by the Boolean values the function takes for any sequence of arguments. The recursive definition of canonical names uses only the abstraction, functional application, the identity operator and the fact that we have a name for the true and the false. We show that this result can be extended to the finite theory of types by the introduction of an algebra on individuals

Parmi l'ensemble de toutes les propositions à propos desquelles un agent rationnel entretient des croyances et des désirs, certaines correspondent à des actes que l'agent juge faisables. Le but de mon intervention est de caractériser ce sous-ensemble de propositions en termes de leur probabilité et de leur désirabilité.Among the set of all propositions on which a rational agent entertains beliefs and desires, some express acts considered as possible options for the agent. The aim of this paper is to characterize this subset of propositions in terms of their probability and their desirability

Le dernier ouvrage d'Yvon Gauthier, son quatrième, n'est certes pas d'une lecture des plus faciles. Le bon lecteur devrait à la fois être familier du formalisme de la mécanique quantique et des labyrinthes lacaniens, connaître la théorie des modéles êt etre revenu de Heidegger.Tout cela rend la tâche d'un critique de Gauthier ardue et périlleuse; aussi je prierai le lecteur de m'excuser à l'avance si, dans le foisonnement philosophique de l'ouvrage, j'ai dû restreindre mon attention à certains aspects particuliers.

SummaryIn this paper I will strive towards three main objectives. First of all, I will try to show that a very commonplace property of knowledge, that of yielding truth, can be used to characterize an ideal and radical notion of knowledge. It will be argued that this property generates a basic and autonomous concept of knowledge, i.e., a purely logical concept of knowledge that can be clearly separated from the psychological, intentional or epistemological aspects of knowledge. What results can thus be regarded as a kind of reduction of the concept of knowledge to that of truth. This reduction will be expressed by means of a criterion which a relation between an agent and a sentence must satisfy in order to be interpreted as exemplifying the relation of knowing.Secondly, 1 will offer an analysis of presuppositional knowledge which shows how the very strong and ideal notion of knowledge previously developed can be useful in interpreting the ordinary use of “knowing”.My third and last objective will be to use this criterion to characterize formally the semantic interpretation associated to a rational and competent agent, i.e. the space of his knowledge

Even though Church’s thesis is widely accepted among mathematicians, it is nonetheless controversial. In this paper, we argue against the position of [Cleland 1993], which defends that Church s thesis must be rejected because the limits of computation depend upon the physical structure of the world. We first give a brief overview of Church’s thesis and then we present Cleland s argument. We then propose a critical analysis of Cleland s argu­ment, which will involve some conceptual distinctions regarding the notion of computability, and finally we will show that the limits of computation are not physical but logical. In short, we argue that computation is limited by the fact that an effective procedure must be described in a finite way.