The stark contrast between the practical success of induction and its apparent philosophical failings raises a question: given the philosophical problems of induction, how do we proceed? To this end, this Element asks what makes it permissible for us to proceed with our inductive practices. It surveys some global problems of induction and reconceptualizes them not only as global skeptical threats but as guides to identifying local, contextual, questions on which inductive reasoning depends. The Element then considers how best to conceptualize our inductive practices, in order to answer such local questions. Examining the limits of formal and material approaches for analyzing problems of induction `in the wild', the Element develops a situated approach in terms of a middle-range framework -- the \textit{inductive pipeline} -- with five semi-general markers: goal, situation, procedure, evidence, and assessment. It proposes that these five markers can guide us in due diligence, and in navigating the risky business of induction, with Humean `doubt, caution, and modesty'.
Some metaphysically hefty idea that matter is objectively distinct in kind from space-and-time is not new. Here we investigate this idea in general relativity by focusing on what it means for something to be `matter'. First, we ask: does the stress-energy tensor provide an objective standard for the matter-spacetime distinction? We highlight a form of shiftiness: whether the same system contributes stress-energy or not can depend on modelling contexts and choices. Second, we study other concepts which play various matter roles: quasi-local and global mass concepts. If these, too, are matter concepts, they undermine any objective, context-independent, spacetime-matter distinction -- the shiftiness compounds. As we'll argue, across these various matter concepts, there is no one ontological line between spacetime and matter, no one intrinsic conceptual line demarcating the boundaries of the matter concept, nor no one extrinsic conceptual line between spacetime and matter.
Philosophers have long worried that certain systems, e.g., black holes or self-gravitating
systems, do not ‘really’ behave thermodynamically. These worries typically hold fixed a thick,
classical thermodynamic notion of equilibrium and then note its apparent failure in new domains. This paper instead articulates a thin, historically rooted concept of equilibrium that is explicitly scale-relative. On this minimal picture, equilibrium applies whenever (i) some properties appear stationary relative to appropriate spatial and temporal scales; (ii) these stationary properties can be represented as balances between counteracting tendencies; and (iii) we can systematically model how the system responds when the balance is perturbed.
We show how this three-part concept underlies familiar uses of equilibrium from classical mechanics to thermodynamics, but also fragments differently in different contexts. We then apply it to two contemporary case studies. In classical and relativistic gravitational thermodynamics, we argue that self-gravitating systems and dynamical black holes admit non-trivial minimal equilibrium regimes, once we attend to scale and to quasi-local horizon structures, even if they lack global thermodynamic equilibria. In quantum statistical mechanics, we argue that prethermal states and generalized Gibbs ensembles support equilibrium reasoning—despite failures of thermalization in the usual Gibbsian sense—because they realize the minimal pattern of balance and response at suitable scales and for restricted classes of observables. Methodologically, we suggest that classical thermodynamics is best viewed as but one historically salient instance of this broader practice of identifying and exploiting minimal equilibrium regimes, rather than as a fixed package to be either fully recovered or abandoned in new domains.
Under review, draft available upon request!
Many quantities central to physics are frame-dependent: one and the same object can be correctly assigned different values of the same general quantity (speed, length, momentum) in different inertial frames. Yet this feature has been largely neglected in the metaphysics of quantities, and it sits uneasily with the familiar single value principle according to which an object cannot have different values of the same quantity at the same time. We begin by isolating the physicist’s basic account of frame-variance and frame-invariance. We then argue that two natural metaphysical reconstructions of such account, including one that is briefly hinted at by philosophers of physics, fail. Finally, inspired by recent discussions in the metaphysics of shape literature (in the context of relativity), we develop two alternative metaphysical accounts of physical quantities that successfully recover the way physicists understand variance and invariance. We close by drawing connections to perspectivalism as well as other kinds of dependencies – such as gauge-dependence – in philosophy of physics.
Draft available upon request!
Density functional theory (DFT) is one of the most popular frameworks through which quantum mechanics is ‘scaled up’ for the many-body modelling of molecules, solids, nuclei, and quantum fluids, yet it has received relatively little philosophical attention. By analyzing DFT’s central organizing structure – Jacob’s Ladder – I argue that DFT’s development presents a distinctive conceptual history of de-idealization. Rather than a linear reversal of idealizing assumptions, I characterize it as a spiral of de-idealization through re-idealization: de-idealizations aimed at reducing residual phenomena which succeed only in virtue of re-introducing new idealizations.
Field approaches to Bohmian quantum field theory face a Grassmann problem, since fermionic wave functionals prescribe Grassmann-valued amplitudes and field configurations which obstruct any natural interpretation of the fundamental ontology. By appealing to some recent advances concerning bosonization, I show how, at least in lattice field contexts, one can interpret any fermionic wave functional as an unproblematic bosonic one with an ordinary non-Grassmann-valued wave functional so long as we revise our understanding of the accompanying laws. Given bosonization, we can mow down the Grassmann problem for lattice field theories, removing one hurdle for field approaches to Bohmian quantum field theories.
Much work in the foundations of statistical mechanics have begun with the following assumption: the arena of inquiry is a classical phase space, over which probability distributions are appropriately defined. That is to say, the domain of inquiry is classical statistical mechanics. Given that we no longer take classical mechanics to be the fundamental realm of physics, a natural question is: what changes in the quantum domain? In this article, we'll do two things. First, we survey the reformulations of old debates -- the thermodynamic arrow of time, emergence and reduction, and the Gibbs vs. Boltzmann debate -- in the quantum domain. Second, we highlight a set of new issues in the foundations of quantum thermodynamics and statistical mechanics: the question of what, if anything, are the appropriate quantum analogues of the concepts of classical statistical mechanics -- work, energy, entropy, and equilibrium/equilibration.