Ontology, Matter and Emergence

“Ontological emergence” of inherent high-level properties with causal powers is witnessed nowhere. A non-substantialist conception of emergence works much better. It allows downward causation, provided our concept of causality is transformed accordingly

The Missing Now

La mayoría de las versiones simplificadas del argumento de McTaggart acerca de la "irrealidad del tiempo" entrañan el supuesto de que los tiempos son predicados monádicos (pasado, presente y futuro) atribuídos a un suceso. En este trabajo se examina minuciosamente la posibilidad de considerarlos como relaciones. La dificultad principal para hacer tal cosa reside en el hecho de que una relación es un predicado diádico, mientras que el suceso ocupa sólo uno de sus lugares. Pero esta dificultad arroja nueva luz sobre el problema del tiempo. El segundo lugar (vacante) en la relación pone de manifiesto, de hecho, el concepto de una entidad que juega un papel en los tiempos y a la que no se puede hacer referencia: el "ahora ausente". Mediante la utilización de este concepto, se pueden exhibir los sutiles desplazanientos del razonamiento subyacentes a algunos pasos cruciales del argumento de McTaggart. Por otra parte, las características únicas del "ahora ausente", confrontadas con situaciones autorreferenciales nos permiten sugerir una forma de ir más allá de la oposición tradicional entre las concepciones "cinemática" y "estática" del tiemp

Réalité donnée, réalité construite. À propos d’un argument de Searle

Un argument important contre le constructivisme social a été formulé par John Searle en 1995. Il consiste non seulement à admettre, mais aussi à analyser jusqu’à ses dernières implications le concept de construction sociale d’une réalité ; puis à prouver que l’une des implications en question est l’impossibilité de généraliser ce concept à toutes les réalités que nous reconnaissons dans la vie quotidienne et dans les sciences. Mieux encore, J. Searle ..

Transcendental Structuralism in Physics: An alternative to Structural Realism

In physics, structures are good candidates for the role of transparadigmatic invariants, which entities can no longer play. This is why structural realism looks more credible than standard entity realism. But why should structures be stable, rather than entities ? Here, structural realists have no answer ; they content themselves with the mere observation that this is how things stand. By contrast, transcendental structuralism (a byproduct of Kant’s transcendental idealism) can easily make sense of this fact. Indeed, it shows that when knowledge bears on phenomena, namely on the emergent byproduct of a relation between the explorer and what is to be explored, this knowledge necessarily bears on relations between such phenomena. After a development on the clarifying power of transcendental structuralism, I turn to an early transcendental structuralist interpretation of quantum mechanics proposed by Jean-Louis Destouches (1909-1980). Destouches, an early French philosopher of physics, was a student of Louis de Broglie. He recasted in the 1940 the very concept of physical theory in the light of quantum physics. According to him, whenever phenomena are inextricably relative to the experimental set-up, a physical theory cannot provide anything beyond a list of interconnected predictions for future facts given a relevant class of past facts. In his general mathematical theory of predictions, the Ψ-functions of quantum mechanics do not refer to some “real” waves; they are shown to be nothing but the formal expression of the phenomena’s being relative to incompatible experimental contexts. Since the quantization of variables can itself be derived from a wave-mechanical formalism, it becomes clear that the most prominent features of quantum mechanics are a mere consequence of contextuality. Destouches thus proved that it is easy to make sense of quantum mechanics provided a reflective attitude is adopted. By contrast, too many difficulties arise when one tries at any cost to make quantum mechanics intelligible within a purely ontological framework

Néo-pragmatisme et incommensurabilité en physique

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.Three interdependent levels are distinguished in Kuhn’s concept of paradigm: experimental know-how, formalism, and ontological commitment. The onlogical level is the only one which happens to be entirely and explicitly expressed in the framework of ordinary language. It then appears that identifying “incommensurability” (of paradigms) with untranslatability is tantamount to skipping part of the problem. To compensate for this incompleteness, a neo-pragmatist and structuralist view of physics is developed along the lines of A. Pickering’s and I. Hacking’s. In this conception, the domain of practice is no longer marginal. It rather becomes the central axis with respect to which every component of knowledge is defined and every question is to be discussed, including the issue of incommensurability

Interplay of packing and flip-flop in local bilayer deformation. How phosphatidylglycerol could rescue mitochondrial function in a cardiolipin-deficient yeast mutant

In a previous work, we have shown that a spatially localized transmembrane pH gradient, produced by acid micro-injection near the external side of cardiolipin-containing giant unilamellar vesicles, leads to the formation of tubules that retract after the dissipation of this gradient. These tubules have morphologies similar to mitochondrial cristae. The tubulation effect is due to direct phospholipid packing modification in the outer leaflet that is promoted by protonation of cardiolipin headgroups. Here we compare the case of cardiolipin-containing giant unilamellar vesicles with that of phosphatidylglycerol-containing giant unilamellar vesicles. Local acidification also promotes formation of tubules in the latter. However, compared to cardiolipin-containing giant unilamellar vesicles the tubules are longer, exhibit a visible pearling and have a much longer lifetime after acid micro-injection is stopped. We attribute these differences to an additional mechanism that increases monolayer surface imbalance, namely inward PG flip-flop promoted by the local transmembrane pH-gradient. Simulations using a fully non-linear membrane model as well as geometrical calculations are in agreement with this hypothesis. Interestingly, among yeast mutants deficient in cardiolipin biosynthesis, only the crd1-null mutant, which accumulates phosphatidylglycerol, displays significant mitochondrial activity. Our work provides a possible explanation of such a property and further emphasizes the salient role of specific lipids in mitochondrial function.Comment: 28 pages, 10 figure

TOWARDS A PHENOMENOLOGICAL CONSTITUTION OF QUANTUM MECHANICS: A QBIST APPROACH

In this programmatic article, our aim is to sketch the outlines of a phenomenological constitution of quantum mechanics, thus drawing the ultimate consequence of previous phenomenological approaches to this theory. In other terms, we wish to show a way to ascend from the situated lived experience of a knowing and acting subject, to the structure and use of the quantum formalism. QBism (Quantum Bayesianism), with its motivated focus on lived experience, and its decision to take the elementary epistemic attitudes of agents as primitives of its axiomatics, will prove a decisive step to progress in this direction