ALL THEMESTHEME - ICHARPAK et al.OMNES, R HEISENBERG,WHAWKING, SSCHÜTTE, DGUICHON, PJANSEN, FK - a JANSEN, FK -b KRÖGER, H BRICMONT, JSCHULMAN,LSBITBOL.M MAILSuncertainty causality |
IS THE UNIVERSE BASED ON HAZARDS ? CONTRIBUTION BITBOL, Michel Directeur de Recherches, CNRS, Philosophie des Sciences CREA, Ecole Polytechnique, 1 rue Descartes 75005 PARIS, FRANCE Professional literature : http://perso.wanadoo.fr/michel.bitbol/page.garde.liste.html yes : for physical theories OPINION TEXTE (received november 2006) Michel Bitbol, « Qu’est-ce qu’un hasard objectif ? »,La lettre mensuelle de l’ECF, n°161, 13-16, 1997. Revisited version of the paper in : Michel Bitbol, " L’aveuglante proximité du réel" Paris : Flammarion, 1998, Chap. 8. Report of the paper : (by Manuel Bächtold, chercheur en philosophie de la physique, Institut für Philosophie - Universität Dortmund ) How should we interpret the indeterminism of Quantum Mechanics? Does it express an objective chance? In his paper « Qu’est-ce qu’un hasard objectif ? », Michel Bitbol provides a careful analysis of this question, before giving his own answer. He recalls the traditional opposition between “subjective” and “objective” chance. Chance is called “subjective” when it results from our ignorance of the causes producing the event under consideration. This conception of chance is due to Laplace. It assumes that the laws governing the world are strictly deterministic. In principle, if we could know these deterministic laws and all the relevant initial conditions, we could reconstitute the entire causal chain leading to the event which at first glance was viewed as occurring randomly. As for the expression “objective chance”, it can refer to two distinct conceptions: the first is ontological, the second Kantian. Let us consider for the moment the ontological conception. It describes chance as a feature of the world “in itself”. This means that the laws of nature are intrinsically indeterministic. In other words, there is simply no cause producing the random event. As Bitbol points out, nothing allows us (or will allow us in the future) to conclude chance is either subjective or ontological. True, Quantum Mechanics – which is actually commonly accepted by the physicists – is indeterministic. This favours an ontological interpretation of chance, as the one of Karl Popper in terms of “propensities”. However, nothing can preclude a priori the possibility that, in the future, a strictly deterministic theory (together with processes of dynamical chaos) will supplant Quantum Mechanics. This possibility, explains Michel Bitbol, is exemplified by the existence of the non-local “hidden variables theory” due to David Bohm. This theory, which provides exactly the same predictions as Quantum Mechanics, claims that the underlying laws governing the world are purely deterministic. Let us turn now to the Kantian conception of objective chance, the one supported by Michel Bitbol. It constitutes a subtle middle path between subjectivism and ontology. The term “objectivity” is here synonymous with “universality”. It concerns not the world “in itself” but the physical theories. More precisely, the chance of Quantum Mechanics is “objective” in the sense of corresponding to a “universal” feature of those physical theories dealing with events occurring in incompatible experimental contexts: (1) any theory whose only aim is to make predictions concerning these “contextual” events is necessarily indeterministic ; and (2) any attempt at completing this theory with the description of some underlying deterministic process (as it is the case in Bohm’s theory) is bound to remain epistemically sterile. Concerning the mathematically proof of this claim, Michel Bitbol refers to a theorem of P. Destouches-Février. see original article of M. Bitbol from his book (pdf, French version) : "L'AVEUGLANTE PROXIMITÉ DU RÉEL" Flamarion, 1998,chapter 8: "Hasard objectif et principe de raison suffisante"http://www.stoqnet.org/italian/gre_altro.html#auletta see INTERNET site of M. Bitbol with an article on (French version) : "Quantum Mechanics" http://perso.orange.fr/michel.bitbol/mecanique.quantique.html |