Jean François

On a mathematically foundational level, our most successful physical theories (gauge field theories and general-relativistic theories) are formulated in a framework based on the differential geometry of connections on principal bundles. After reviewing the essentials of this framework, we articulate the generalized hole and point-coincidence arguments, examining how they weight on a substantivalist position towards bundle spaces. This question, then, is considered in light of the Dressing Field Method, which allows a manifestly invariant reformulation of gauge field theories and general-relativistic theories, making their conceptual structure more transparent: it formally implements the point-coincidence argument and thus allows to define (dressed) fields and (dressed) bundle spaces immune to hole-type arguments.

In recent years, crop diversification has been promoted among management strategies demonstrating beneficial impacts on agricultural productivity and ecosystem health, thus providing a pathway toward sustainable agricultural futures. However, while some research has explored the conditions that enable or support systems that are both diverse and productive, there remains a need for further study to deepen our understanding across different regions and contexts. We address this gap by examining influencing factors and contexts that result in systems with high crop productivity and contrasting crop diversity trajectories. We conducted in-depth interviews with fifty agricultural stakeholders across four U.S. counties in two different regions, each pair of counties representing opposing trends in cropping system diversity since 2008. Our analysis identified five groups of factors that consistently influenced crop selection decisions and agricultural system change, encompassing economic, social, policy, techno-managerial, and biophysical factors. Our findings demonstrate more similarities than dissimilarities in the factors influencing farmer crop selection decisions across all counties. Subtle differences derived from how certain crop selection factors – such as climate variability, soil type, labor dynamics, and policies – interacted within specific contexts. Our findings suggest that biophysical variability and historical legacies of diverse cropping contribute to current patterns of diversification, with larger populations and alternative market demands further supporting diverse agricultural systems. This work reinforces the need to account for the dynamic contexts at local and regional levels in research and intervention aimed at promoting crop diversification.

There is solid consensus among physicists and philosophers that, in gauge field theory, for a quantity to be physically meaningful or real, it must be gauge-invariant. Yet, every “elementary” field in the Standard Model of particle physics is actually gauge-variant. This has led a number of researchers to insist that new manifestly gauge-invariant approaches must be established. Indeed, in the foundational literature, dissatisfaction with standard methods for reducing gauge symmetries has been expressed: Spontaneous symmetry breaking is deemed conceptually dubious, while gauge fixing suffers the same limitations and is subject to the same criticisms as coordinate choices in General Relativity. An alternative gauge-invariant proposal was recently introduced in the literature, the so-called “dressing field method” (DFM). It is a mathematically subtle tool, and unfortunately prone to be confused with simple gauge transformations, hence with standard gauge fixings. As a matter of fact, in the physics literature the two are often conflated, and in the philosophy community some doubts have been raised about whether there is any substantial difference between them. Clarifying this issue is of special significance for anyone interested in both the foundational issues of gauge theories and their invariant formulation. It is thus our objective to establish as precisely as possible the technical and conceptual distinctions between the DFM and gauge fixing.

L'acüon educative repose sur un double fondement: d'une part, la nature et la vocation de l'etre humain, et d'autre part, la societe humaine ä bätir. L'homme a des traits specifiques qui exigent et en meme temps permettent son education: il est imparfait, inacheve (il ne sait pas tout, il ne se comporte pas for cement bien), il faut done l'amener ä s'ameliorer; il est perfectible e'est-a-dire qu'il peut devenir meilleur; il a la volonte de se depasser, de tendre vers l'ideal, ideal qu'il n'atteint, bien sür, jamais; il est capable materiellement, intellectuellement (grace ä sa formation, ä son experience) d'agir sur autrui, de le mener vers cet ideal; enfln, il est conscient de devoir le faire, car l'homme ne peut et ne doit etre eduque que par l'homme. Et, second justificatif de Taction educative: la societe des hommes et les rapports devant exister entre eux. L'homme, par essence, Vit et est fait pour vivre en collectivite. Celle-ci doit etre harmonieuse, bien organisee, de preference sous forme d'Etat, pour le bonheur de tous les membres, lesquels doivent etre ä meme de concourir ä l'edification d'une societe egalitaire, toutes choses qui necessitent Taction educative.