Publications

 

Baptiste Le Bihan (forthcoming). ‘Holistic Versus Fragmented Multiverses: Empirical Access via Causal and Grounding Signatures.’
Can multiverse hypotheses ever receive empirical support? Critics argue that multiverse scenarios posit unobservable entities, face severe underdetermination, or fall outside the bounds of science. This chapter challenges that view by offering a naturalistic metaphysical counterpoint to Bayesian approaches, distinguishing fragmented from holistic multiverses. Scientific proposals are almost always holistic: they embed universes within a unifying physical or metaphysical structure that can, in principle, leave empirical signatures inside the universes. I develop a typology of such signatures and show how it applies to leading scenarios from quantum theory, cosmology, and string theory. This framework clarifies why objections such as the ‘this universe’ objection and a newly articulated generalization, the epistemic isolation objection, fail against scientifically motivated multiverses. The upshot is a qualified defence: while fragmented multiverses remain empirically inaccessible, certain holistic multiverses could, in principle, be supported by the same epistemic
standards used elsewhere in physics.

Baptiste Le Bihan, Emilia Margoni and Annica Vieser (forthcoming). ‘Possibility in Physics’.
Physics not only describes past, present, and future events but also accounts for unrealized possibilities. These possibilities are represented through the solution spaces given by theories. These spaces are typically classified into two categories: kinematical and dynamical. The distinction raises important questions about the nature of physical possibility. How should we interpret the difference between kinematical and dynamical models? Do dynamical solutions represent genuine possibilities in the physical world? Should kinematical possibilities be viewed as mere logical or linguistic constructs, devoid of a deeper connection to the structure of physical reality? This chapter addresses these questions by analyzing some of the most significant theories in physics: classical mechanics, general relativity and quantum mechanics, with a final mention to quantum gravity. We argue that only dynamical models correspond to genuine physical possibilities.

Emilia Margoni and Daniele Oriti (forthcoming). ‘The Emergence of Spacetime: What Role for Functionalism?’, The British Journal for the Philosophy of Science.
Among the various attempts to formulate a theory of quantum gravity, one class of approaches suggests that spacetime, as modelled by general relativity, is destined to fade away. A major issue then becomes identifying which structures may inhabit the more fundamental, non-spatiotemporal environment, as well as explaining their relationship with the higher-level spatiotemporal physics. Recently, it has been suggested that a certain understanding of functionalism is the proper framework to suitably account for the recovery of spacetime. In this article, the viability and usefulness of such a conceptual strategy is explored, by looking at the various levels of spacetime emergence a theory of quantum gravity is expected to deal with. Our conclusion is that while the applicability of spacetime functionalism is also available in a quantum gravity context, its import remains rather unsettled.

Daniel Grimmer, Enrico Cinti and Rasmus Jaksland (forthcoming). ‘Duality, Underdetermination, and the Uncommon Common Core’, The British Journal for the Philosophy of Science.
ABSTRACT: Dualities arise when two seemingly different descriptions of the world are physically equivalent, suggesting that either description can be used to describe a given system. This raises the question of which description, if any, is true and raises worries of empirical underdetermination. This paper explores the underdetermination problem in the context of dualities and focuses on the viability of a common core ontology as a solution. The common core suggests that one should only ontologically commit to what is invariant under the duality map between the dual descriptions. The paper examines this solution through the lens of Fourrier duality in non-relativistic quantum mechanics and raises concerns about the existence and adequacy of the common core. It argues that the common core might not be ontologically rich enough to support a genuine realist commitment and questions whether it should be preferred over the dual descriptions. By doing so, the analysis highlights the challenges of employing the common core interpretation in quantum mechanics and also in other dualities such as T-duality and AdS/CFT, especially for purposes of breaking underdetermination. Dualities are, we conclude, likely examples of underdetermination and therefore a challenge to scientific realism.

Sam Baron, Baptiste Le Bihan and James Read (2025). ‘Scientific Theory and Possibility’, Erkenntnis.
It is plausible that the models of scientific theories correspond to possibilities. But how do we know which models of which scientific theories so correspond? This paper provides a novel proposal for guiding belief about possibilities via scientific theories. The proposal draws on the notion of an effective theory: a theory that applies very well to a particular, restricted domain. We argue that it is the models of effective theories that we should believe correspond, at least in part, to possibilities. It is thus effective theories that should guide modal reasoning in science.

Enrico Cinti and Marco Sanchioni (2025). ‘Bridging supersymmetry and the spin-statistics theorem: a quest for emergence’, Synthese 205 (3): 1-22.
The coexistence of Supersymmetry (SUSY) and the Spin-Statistics Theorem (SST) poses a challenge, given their seeming incompatibility. While SUSY connects particles with distinct spins, SST links particle’s spin to their statistics. We propose a solution to this puzzle: both spin and SST may emerge as low-energy phenomena. To do so, we look at SUSY breaking at lower energy scales, exploring if this mechanism aligns with the concept of emergence. The paper presents a comprehensive review of the SUSY-SST tension, a philosophical introduction to SUSY-breakig, and an argument for spin and SST emergence within SUSY. Overall, our aim is to show how SUSY and SST can coexist in the same theory and thus deepen our understanding of SUSY quantum field theory.

Enrico Cinti, Cristian Mariani and Marco Sanchioni (2025). ‘The Unbearable Indefiniteness of Spacetime’, Foundations of Physics 55 (1): 1-25.
The coexistence of Supersymmetry (SUSY) and the Spin-Statistics Theorem (SST) poses a challenge, given their seeming incompatibility. While SUSY connects particles with distinct spins, SST links particle’s spin to their statistics. We propose a solution to this puzzle: both spin and SST may emerge as low-energy phenomena. To do so, we look at SUSY breaking at lower energy scales, exploring if this mechanism aligns with the concept of emergence. The paper presents a comprehensive review of the SUSY-SST tension, a philosophical introduction to SUSY-breakig, and an argument for spin and SST emergence within SUSY. Overall, our aim is to show how SUSY and SST can coexist in the same theory and thus deepen our understanding of SUSY quantum field theory.

Baptiste Le Bihan (2024). ‘The Great Loop: From Conformal Cyclic Cosmology to Aeon Monism’, Journal for General Philosophy of Science.
Penrose’s conformal cyclic cosmology describes the cosmos as a collection of successive universes, the so-called aeons. The beginning and ending of our universe are directly connected to two other, anterior and posterior, universes. Penrose considers but rules out a different interpretation of conformal cyclic cosmology: that the beginning of our universe is connected to its own end in a cosmic loop. The paper argues that the view, aeon monism, should be regarded as a natural interpretation of conformal cyclic cosmology and discusses its implications for the concept of eternal return in light of the most popular metaphysics of time.

Sam Baron and Baptiste Le Bihan (2024). ‘Causal Theories of Spacetime’, Noûs 58 (1): 202–224. 
We develop a new version of the causal theory of spacetime. Whereas traditional versions of the theory seek to identify spatiotemporal relations with causal relations, the version we develop takes causal relations to be the grounds for spatiotemporal relations. Causation is thus distinct from, and more basic than, spacetime. We argue that this non-identity theory, suitably developed, avoids the challenges facing the traditional identity theory.

Emilia Margoni (2024). ‘Adynamism in Physics: The Block Universe vs Barbour’s Relational Strategy’, Journal for General Philosophy of Science.
The block universe is generally considered as the metaphysical position that best accommodates the outcomes of relativistic physics. Its most consistent formulation postulates a static universe where change is not admitted. However, some of its advocates try to reconcile its basic adynamical commitments as to the nature of physical reality with certain aspects of dynamism that arise, for instance, within human experience. In this article, I first examine how some block viewers try to reconcile dynamism and adynamism. I then go on to discuss the problems that emerge while trying to make room for dynamism within the block. To this end, I clarify the meaning of adynamism and explains what it takes to eradicate dynamism through the implementation of the so-called “Langrangian schema”. Based on this analysis, I juxtapose two resolute attempts at the formulation of a thoroughly adynamical project. The first, named relational block world, aims to make the block view totally static. The second, Barbour’s early works on the implementation of a neo-Machian relational strategy, makes the point that a complete adynamism cannot be achieved within relativity and its metaphysical counterpart. The article in conclusion argues that, by dismissing four-dimensionalism and embracing three-dimensionalism, Barbour proves better at promoting an utterly static physics.