Michel Bitbol

Les études que nous rassemblons ici font écho aux débats les plus récents sur la philosophie des mathématiques de Wittgenstein, qui est bien certainement l'aspect le plus controversé de son œuvre. Elles sont, pour l'essentiel, consacrées au statut et aux fonctions des preuves mathématiques et aux "réactions" du philosophe aux théorèmes de Gödel. C'est dire qu'elles tournent autour de l'anti-platonisme foncier de Wittgenstein en philosophie des mathématiques et de son refus catégorique de toute méta-mathématique. E. R.

There are two versions of the putative connection between consciousness and the measurement problem of quantum mechanics : consciousness as the cause of state vector reduction, and state vector reduction as the physical basis of consciousness. In this article, these controversial ideas are neither accepted uncritically, nor rejected from the outset in the name of some prejudice about objective knowledge. Instead, their origin is sought in our most cherished (but disputable) beliefs about the place of mind and consciousness in the world. It is first pointed out that these common beliefs about mind and consciousness arise from reification of situated first-person experience. Then, situatedness is shown to be a constitutive part of any exhaustive treatment of quantum measurements. It turns out that the alleged connection between consciousness and the measurement problem is a symptom of (i) the ineliminability of our being situated from the end-product of science, and (ii) our difficulty to express correctly this being situated.

Open peer commentary on the article “Never Mind the Gap: Neurophenomenology, Radical Enactivism, and the Hard Problem of Consciousness” by Michael D. Kirchhoff & Daniel D. Hutto. Upshot: We point out that the significance of the neurophenomenological approach to the “hard problem” of consciousness is underrated and misunderstood by the authors of the target article. In its original version, neurophenomenology implies nothing less than a change in our own being to dispel the mere sense that there is a problem to be theoretically solved or dissolved. Neurophenomenology thus turns out to be much more radical than the enactivist kind of dissolution promoted by the authors.

It is pointed out that the probabilistic character of a theory does not indicate by itself a distancing with respect to the norms of objectification. Instead, the very structure of the calculation of probabilities utilised by this theory is capable of bearing the trace of a constitution of objectivity in Kant’s sense. Accordingly, the procedure of the constitution of objectivity is first studied in standard and in quantum cases with due reference to modern cognitive science. Then, an examination of the differences between classical and quantum probabilities is performed. It is shown that the form of the quantum calculation of the probabilities carries the mark of the contextuality of the phenomena on which it bears. Conversely, certain conditions that have the form of Bell’s inequalities carry the mark of decontextualization

The concept of well-defined and mutually exclusive objective facts has no counterpart in the formalism of standard quantum mechanics. Bypassing decoherence theories, we then inquire into the conditions of use of this concept of objective fact, and find that it is grounded on the possibility of making reference to spatio-temporal continuants and permanent properties. Since these conditions are not fulfilled within the quantum paradigm, one must look for appropriate substitutes. Two such substitutes are discussed. The first one is phenomenal fact , whose relevance to quantum physics is evaluated in the framework of Husserl’s phenomenology. The second substitute is intersubjective agreement, which can be disconnected from objectivity stricto sensu, as quantum mechanics seems to require. A study of intersubjectivity in terms of the pragmatics of language is undertaken. This study is applied to both Everett’s symbolism of memory brackets and Bohr’s transcendental remark that description of scientific experiments cannot dispense with ordinary language

On distingue trois strates interdépendantes dans les paradigmes kuhniens : le savoir-faire expérimental, le formalisme, et les engagements ontologiques. Seul le niveau ontologique se trouve intégralement et explicitement exprimé dans le cadre du langage courant. Il semble donc qu’assimiler l’« incommensurabilité » des paradigmes à une intraductibilité revient à esquiver une partie du problème. Afin de compenser cette apparente incomplétude, une conception néo-pragmatiste et structuraliste de la physique est développée, en l’appuyant sur les réflexions d’A. Pickering et I. Hacking. Au lieu d’être marginalisé, le domaine des pratiques devient dans cette conception l’axe central où se définissent toutes les composantes de la connaissance, et où se décident toutes les questions, y compris celle de l’incommensurabilité.

In recent years, many philosophers of modern physics came to the conclusion that the problem of how objectivity is constituted (rather than merely given) can no longer be avoided, and therefore that a transcendental approach in the spirit of Kant is now philosophically relevant. The usual excuse for skipping this task is that the historical form given by Kant to transcendental epistemology has been challenged by Relativity and Quantum Physics. However, the true challenge is not to force modern physics into a rigidly construed static version of Kant's philosophy, but to provide Kant's method with flexibility and generality. In this book, the top specialists of the field pin down the methodological core of transcendental epistemology that must be used in order to throw light on the foundations of modern physics. First, the basic tools Kant used for his transcendental reading of Newtonian Mechanics are examined, and then early transcendental approaches of Relativistic and Quantum Physics are revisited. Transcendental procedures are also applied to contemporary physics, and this renewed transcendental interpretation is finally compared with structural realism and constructive empiricism. The book will be of interest to scientists, historians and philosophers who are involved in the foundational problems of modern physics

The two major options on which the current debate on the interpretation of quantum mechanics relies, namely realism and empiricism, are far from being exhaustive. There is at least one more position available, which is metaphysically as agnostic as empiricism, but which shares with realism a committment to considering the structure of theories as highly significant. The latter position has been named transcendentalism after Kant. In this paper, a generalized version of Kant's method is used. This yields a reasoning that one is entitled to call a transcendental deduction of some major formal features of quantum mechanics.

Emergence is interpreted in a non-dualist framework of thought. No metaphysical distinction between the higher and basic levels of organization is supposed, but only a duality of modes of access. Moreover, these modes of access are not construed as mere ways of revealing intrinsic patterns of organization: They are supposed to be constitutive of them, in Kant’s sense. The emergent levels of organization, and the inter-level causations as well, are therefore neither illusory nor ontologically real: They are objective in the sense of transcendental epistemology. This neo-Kantian approach defuses several paradoxes associated with the concept of downward causation, and enables one to make good sense of it independently of any prejudice about the existence (or inexistence) of a hierarchy of levels of being

Open peer commentary on the article “Enaction as a Lived Experience: Towards a Radical Neurophenomenology” by Claire Petitmengin. Upshot: Petitmengin’s strategy of dissolution of the “hard problem” of consciousness is shown to rely on some radical phenomenological premises that are listed and analyzed. It presupposes a starting point of research in a state of epoché ; it unfolds into a participatory conception of truth; and it ends in a quest for non-dual pristine experience. Each one of these moves is endorsed and amplified.

Le présent tome traite de la mécanique quantique non relativiste. Il comprend, outre ses fondements, de multiples applications de la mécanique quantique dans une plus large mesure que dans les cours généraux. Dans leur exposé des questions générales, les auteurs dégagent au maximum l'essence physique de la théorie, à partir de laquelle ils développent l'appareil mathématique. Contrairement au schéma habituel allant des théorèmes mathématiques relatifs aux opérateurs linéaires, les auteurs déduisent les exigences mathématiques auxquelles doivent répondre les opérateurs et les fonctions propres à partir de la position physique du problème. Des compléments mathématiques sont donnés en appendice.

This paper reviews the debate between Carnap and Schrödinger about Hypothesis P (It is not only I who have perceptions and thoughts; other human beings have them too)–a hypothesis that underlies the possibility of doing science. For Schrödinger this hypothesis is not scientifically testable; for Carnap it is. But Schrödinger and Carnap concede too much to each other and miss an alternative understanding: science does not depend on an explicit hypothesis concerning what other human beings see and think; it is simply a practice of communication which anticipates or presupposes the perfect interchangeability of positions amongst the members of the linguistic community. The mentalistic vocabulary of folk-psychology, used by Carnap and Schrödinger, does not take first but last place in this perspective; because it does nothing but express after the event the confidence to which the disputants bear witness regarding a generally successful practice of communication.