Michel Bitbol

The reduction of the concept of heat to that of molecular kinetic energy is recurrently presented as lending analogical support to the project of reduction of phenomenal concepts to physical concepts. The claimed analogy draws on the way the use of the concept of heat is attached to the experience in first person of a certain sensation. The reduction of this concept seems to prove the possibility to reduce discourse involving phenomenal concepts to a scientific description of neural activity. But is this analogy really justified? We will show that if there is an analogy, far from speaking for a reduction of phenomenal concepts, it rather stresses the necessity to integrate phenomenal reports in the scientific study of experience.

In his book _The Empirical Stance_, Bas van Fraassen develops a strong and subtle attack on materialism. This chapter amplifies this criticism from a mainly neo-Kantian standpoint, and identifies by contrast some reasons why van Fraassen tends to baulk at the ultimate consequences of his contest. It first reviews van Fraassen's construal of materialism as a _stance_, and examines some motives many thinkers have to resist this idea. It goes on to describe the drifting conceptions of ‘matter’ according to materialists, and states two motives to be less indulgent than van Fraassen for the particulate conception of matter. The chapter then documents the first motive: loss of the basic cognitive conditions that would enable the particulate conception of matter to provide us with a coherent and unified representation. It also examines a general criterion of materiality, beyond the circular statement that matter is composed of material particles: matter must be both objective and able to manifest itself in space-time. The chapter then applies this criterion and finds difficulties on both sides of the Cartesian divide. It then states a meta-value (progressiveness, open-mindedness) that is shared by materialists to a certain extent, but shows that both empiricism and neo-Kantianism fare better with respect to this meta-value. Finally some limitations in van Fraassen's position that prevent him from offering a far enough reaching critique of materialism are presented.

A concept of the ‘actual now’ is introduced. The ‘actual now’ is negatively characterized by the fact that it is absent from the time-series. This does not mean that the ‘actual now’ is outside the time-series. For saying so would wrongly suggest the existence of an ‘outside’ where the ‘actual now’ could be located. Instead, one considers that the ‘actual now’ is just the name of ‘that with respect to which’ any event can be said to be past or future, yet being no event by itself. It holds the same role with respect to time as Husserl’s transcendental ego with respect to the empirical self. McTaggart’s celebrated refutation of the reality of time is reinterpreted accordingly. To express this argument, one no longer needs to use the notions of ‘change’ or ‘time flow’, but only to point out the in-principle impossibility to refer to the ‘actual now’

Toute science, admet-on, commence par détacher un objet en le rendant indépendant des sujets et des situations. Mais cette conception étroite de la connaissance scientifique laisse subsister des zones d'ombre. La conscience n'est pas un objet. Elle est ce sans quoi rien ne pourrait être pris pour objet. La conscience n'est pas détachable des sujets, car elle s'identifie à ce qui est vécu par un sujet. De façon analogue, en physique quantique, un phénomène n'est pas dissociable de son contexte expérimental, car il s'identifie à ce qui se manifeste à grande échelle au laboratoire. Que faire pour ne pas laisser ces cas extrêmes de côté? Généraliser la méthode scientifique. Ne plus la borner à définir et à caractériser des objets, mais l'étendre à la coordination directe des expériences. Telle est la révolution de pensée qu'il faut accomplir pour résoudre, ou plutôt dissoudre, deux questions-limites de la science : le problème de l'origine de la conscience et le paradoxe du "chat de Schrödinger" en physique quantique.

Quel est le sens des théories physiques? Il fut une époque où le débat entre réalistes et anti-réalistes ne souffrait guère de nuances. Le réalisme scientifique était vide parce qu'il renvoyait à un ailleurs ou à un futur indéfinis ; l'anti-réalisme était aveuglé parce qu'il privait la recherche de but et de direction. Aujourd'hui, bien des réalistes ont appris à se défaire des équivalences rigides entre l'objectivité et la réalité, entre l'objet visé et la " cause " des phénomènes, entre l'invariant et l'en-soi, entre la pratique structurée de la recherche et la préexistence des structures. Et les anti-réalistes, qui adhéraient à la surface des " faits ", des opérations et des interactions sociales, n'ignorent plus les projets, les engagements et les valeurs. Ni les uns ni les autres ne se satisfont désormais d'un strict dualisme entre le donné et le construit. La voie s'en trouve dégagée pour une réappréciation des " étrangetés " de la mécanique quantique : elles ne témoigneraient pas de la distance excessive qui nous sépare du réel ; elles ne nous contraindraient pas davantage à l'agnosticisme. Elles sont peut-être le signe ambigu mais récurrent de l'aveuglante proximité du réel. Reprenant en partie certains de ses propres travaux de recherche, Michel Bitbol appuie ces orientations sur des études de cas concernant l'atomisme, le " vide quantique ", le hasard, la naissance des théories physiques du XXe siècle et le concept d' " état relatif ".

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.

Context: We are presently witnessing a revival of introspective methods, which implicitly challenges an impressive list of in-principle objections that were addressed to introspection by various philosophers and by behaviorists. Problem: How can one overcome those objections and provide introspection with a secure basis? Results: A renewed definition of introspection as “enlargement of the field of attention and contact with re-enacted experience,” rather than “looking-within,” is formulated. This entails (i) an alternative status of introspective phenomena, which are no longer taken as revelations of some an sich slice of experience, but as full-fledged experiences; and (ii) an alternative view of the validity of first-person reports as “performative coherence” rather than correspondence. A preliminary empirical study of the self-assessed reliability of introspective data using the elicitation interview method is then carried out. It turns out that subjects make use of reproducible processual criteria in order to probe into the authenticity and completeness of their own introspective reports. Implications: Introspective inquiry is likely to have enough resources to “take care of itself.” Constructivist content: It is argued that the failure of the introspectionist wave of the turn of the 19th/20th centuries is mostly due to its unconditional acceptance of the representationalist theory of knowledge, and that alternative non-representationalist criteria of validity give new credibility to introspective knowledge.

Rovelli’s RQM is first characterized by contrast with both Everett’s and Bohr’s interpretations of quantum mechanics. Then, it is shown that a basic difficulty arises from the choice of formulating RQM in a naturalistic framework. Even though, according to Rovelli’s interpretation, statements about the world only make sense relative to certain naturalized observers described by means of quantum mechanics, this very meta-statement seems to make sense relative to a sort of super-observer which does not partake of the naturalized status of ordinary observers. The difficulty is solved by substituting functional reference frames for physical (or naturalized) observers throughout. Instead of being relative to physical observers, statements about the state vector of physical systems are here relative to well-defined projects of probabilistic prediction which may be embodied by several physical observers.

Context: In his work on neurophenomenology, the late Francisco Varela overtly tackled the well-known “hard problem” of the (physical) origin of phenomenal consciousness. Problem: Did he have a theory for solving this problem? No, he declared, only a “remedy.” Yet this declaration has been overlooked: Varela has been considered (successively or simultaneously) as an idealist, a dualist, or an identity theorist. Results: These primarily theoretical characterizations of Varela’s position are first shown to be incorrect. Then it is argued that there exists a stance (let’s call it the Varelian stance) in which the problem of the physical origin of primary consciousness, or pure experience, does not even arise. Implications: The nature of the “hard problem” of consciousness is changed from an intellectual puzzle to an existential option. Constructivist content: The role of ontological prejudice about what the world is made of (a prejudice that determines the very form of the “hard problem” as the issue of the origin of consciousness out of a pre-existing material organization) is downplayed, and methodologies and attitudes are put to the fore.

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.

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.

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 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.

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.