•  133
    Scientific polarization
    with Cailin O’Connor
    European Journal for Philosophy of Science 8 (3): 855-875. 2017.
    Contemporary societies are often “polarized”, in the sense that sub-groups within these societies hold stably opposing beliefs, even when there is a fact of the matter. Extant models of polarization do not capture the idea that some beliefs are true and others false. Here we present a model, based on the network epistemology framework of Bala and Goyal, 784–811 1998), in which polarization emerges even though agents gather evidence about their beliefs, and true belief yields a pay-off advantage.…Read more
  •  129
    I articulate and discuss a geometrical interpretation of Yang–Mills theory. Analogies and disanalogies between Yang–Mills theory and general relativity are also considered.
  •  116
    On G.E. Moore’s ‘Proof of an External World’
    Pacific Philosophical Quarterly 98 (2). 2017.
    A new reading of G.E. Moore's ‘Proof of an External World’ is offered, on which the Proof is understood as a unique and essential part of an anti-sceptical strategy that Moore worked out early in his career and developed in various forms, from 1909 until his death in 1958. I begin by ignoring the Proof and by developing a reading of Moore's broader response to scepticism. The bulk of the article is then devoted to understanding what role the Proof plays in Moore's strategy, and how that role is …Read more
  •  99
    The Geometry of Conventionality
    Philosophy of Science 81 (2): 233-247. 2014.
    There is a venerable position in the philosophy of space and time that holds that the geometry of spacetime is conventional, provided one is willing to postulate a “universal force field.” Here we ask a more focused question, inspired by this literature: in the context of our best classical theories of space and time, if one understands “force” in the standard way, can one accommodate different geometries by postulating a new force field? We argue that the answer depends on one’s theory. In Newt…Read more
  •  97
    I argue that a criterion of theoretical equivalence due to Glymour :227–251, 1977) does not capture an important sense in which two theories may be equivalent. I then motivate and state an alternative criterion that does capture the sense of equivalence I have in mind. The principal claim of the paper is that relative to this second criterion, the answer to the question posed in the title is “yes”, at least on one natural understanding of Newtonian gravitation.
  •  94
    The Scope and Generality of Bell’s Theorem
    Foundations of Physics 43 (9): 1153-1169. 2013.
    I present a local, deterministic model of the EPR-Bohm experiment, inspired by recent work by Joy Christian, that appears at first blush to be in tension with Bell-type theorems. I argue that the model ultimately fails to do what a hidden variable theory needs to do, but that it is interesting nonetheless because the way it fails helps clarify the scope and generality of Bell-type theorems. I formulate and prove a minor proposition that makes explicit how Bell-type theorems rule out models of th…Read more
  •  89
    I offer one possible explanation of why inertial and gravitational mass are equal in Newtonian gravitation. I then argue that the explanation given is an example of a kind of explanation that is not captured by standard philosophical accounts of scientific explanation. Moreover, this form of explanation is particularly important, at least in physics, because demands for this kind of explanation are used to motivate and shape research into the next generation of physical theories.
  •  84
    On the status of the geodesic principle in Newtonian and relativistic physics
    Studies in History and Philosophy of Science Part A 42 (4): 276-281. 2011.
    A theorem due to Bob Geroch and Pong Soo Jang ["Motion of a Body in General Relativity." Journal of Mathematical Physics 16, ] provides a sense in which the geodesic principle has the status of a theorem in General Relativity. I have recently shown that a similar theorem holds in the context of geometrized Newtonian gravitation [Weatherall, J. O. "The Motion of a Body in Newtonian Theories." Journal of Mathematical Physics 52, ]. Here I compare the interpretations of these two theorems. I argue …Read more
  •  65
    Regarding the ‘Hole Argument’
    British Journal for the Philosophy of Science. 2016.
    I argue that the Hole Argument is based on a misleading use of the mathematical formalism of general relativity. If one is attentive to mathematical practice, I will argue, the Hole Argument is blocked.
  •  56
    Understanding Gauge
    Philosophy of Science 83 (5): 1039-1049. 2016.
    I consider two usages of the expression "gauge theory". On one, a gauge theory is a theory with excess structure; on the other, a gauge theory is any theory appropriately related to classical electromagnetism. I make precise one sense in which one formulation of electromagnetism, the paradigmatic gauge theory on both usages, may be understood to have excess structure, and then argue that gauge theories on the second usage, including Yang-Mills theory and general relativity, do not generally have…Read more
  •  53
    Categories and the Foundations of Classical Field Theories
    In Elaine Landry (ed.), Categories for the Working Philosopher, Oxford University Press. forthcoming.
    I review some recent work on applications of category theory to questions concerning theoretical structure and theoretical equivalence of classical field theories, including Newtonian gravitation, general relativity, and Yang-Mills theories.
  •  53
    We study the Johansen–Ledoit–Sornette model of financial market crashes :219–255, 2000). On our view, the JLS model is a curious case from the perspective of the recent philosophy of science literature, as it is naturally construed as a “minimal model” in the sense of Batterman and Rice :349–376, 2014) that nonetheless provides a causal explanation of market crashes, in the sense of Woodward’s interventionist account of causation.
  •  41
    On Representational Redundancy, Surplus Structure, and the Hole Argument
    with Clara Bradley
    Foundations of Physics 50 (4): 270-293. 2020.
    We address a recent proposal concerning ‘surplus structure’ due to Nguyen et al.. We argue that the sense of ‘surplus structure’ captured by their formal criterion is importantly different from—and in a sense, opposite to—another sense of ‘surplus structure’ used by philosophers. We argue that minimizing structure in one sense is generally incompatible with minimizing structure in the other sense. We then show how these distinctions bear on Nguyen et al.’s arguments about Yang-Mills theory and o…Read more
  •  40
    I review the philosophical literature on the question of when two physical theories are equivalent. This includes a discussion of empirical equivalence, which is often taken to be necessary, and sometimes taken to be sufficient, for theoretical equivalence; and "interpretational" equivalence, which is the idea that two theories are equivalent just in case they have the same interpretation. It also includes a discussion of several formal notions of equivalence that have been considered in the rec…Read more
  •  40
    Collective Belief, Kuhn, and the String Theory Community
    In Michael S. Brady & Miranda Fricker (eds.), The Epistemic Life of Groups, Oxford University Press. pp. 191-217. 2016.
    One of us [Gilbert, M.. “Collective Belief and Scientific Change.” Sociality and Responsibility. Lanham, MD: Rowman & Littlefield. 37-49.] has proposed that ascriptions of beliefs to scientific communities generally involve a common notion of collective belief described by her in numerous places. A given collective belief involves a joint commitment of the parties, who thereby constitute what Gilbert refers to as a plural subject. Assuming that this interpretive hypothesis is correct, and that s…Read more
  •  36
    A brief remark on energy conditions and the Geroch-Jang Theorem
    Foundations of Physics 42 (2): 209-214. 2012.
    The status of the geodesic principle in General Relativity has been a topic of some interest in the recent literature on the foundations of spacetime theories. Part of this discussion has focused on the role that a certain energy condition plays in the proof of a theorem due to Bob Geroch and Pong-Soo Jang [“Motion of a Body in General Relativity.” Journal of Mathematical Physics 16(1) (1975)] that can be taken to make precise the claim that the geodesic principle is a theorem, rather than a pos…Read more
  •  35
    Interpreting Quantum Theories
    Philosophical Review 124 (2): 275-278. 2015.
  •  32
    We discuss some recent work by Tim Maudlin concerning Black Hole Information Loss. We argue, contra Maudlin, that there is a paradox, in the straightforward sense that there are propositions that appear true, but which are incompatible with one another. We discuss the significance of the paradox and Maudlin's response to it.
  •  31
    Some Philosophical Prehistory of the (Earman-Norton) hole argument
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 70 79-87. 2020.
    The celu of the philosophical literature on the hole argument is the 1987 paper by Earman \& Norton ["What Price Space-time Substantivalism? The Hole Story" Br. J. Phil. Sci.]. This paper has a well-known back-story, concerning work by Stachel and Norton on Einstein's thinking in the years 1913-15. Less well-known is a connection between the hole argument and Earman's work on Leibniz in the 1970s and 1980s, which in turn can be traced to an argument first presented in 1975 by Howard Stein. Remar…Read more
  •  31
    Why Be regular?, part I
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 65 122-132. 2019.
  •  31
    I address a question recently raised by Simon Saunders [Phil. Sci. 80: 22-48 ] concerning the relationship between the spacetime structure of Newton-Cartan theory and that of what I will call "Maxwell-Huygens spacetime". This discussion will also clarify a connection between Saunders' work and a recent paper by Eleanor Knox [Brit. J. Phil. Sci. 65: 863-880 ].
  •  30
    Against dogma: On superluminal propagation in classical electromagnetism
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 48 (2): 109-123. 2014.
    It is deeply entrenched dogma that relativity theory prohibits superluminal propagation. It is also experimentally well-established that under some circumstances, classical electromagnetic fields propagate through a dielectric medium with superluminal group velocities and superluminal phase velocities. But it is usually claimed that these superluminal velocities do not violate the relativistic prohibition. Here I analyze electromagnetic fields in a dielectric medium within a framework for unders…Read more
  •  29
    Inertial motion, explanation, and the foundations of classical spacetime theories
    In Dennis Lehmkuhl, Gregor Schiemann & Erhard Scholz (eds.), Towards a Theory of Spacetime Theories, Birkhauser. pp. 13-42. 2017.
    I begin by reviewing some recent work on the status of the geodesic principle in general relativity and the geometrized formulation of Newtonian gravitation. I then turn to the question of whether either of these theories might be said to ``explain'' inertial motion. I argue that there is a sense in which both theories may be understood to explain inertial motion, but that the sense of ``explain'' is rather different from what one might have expected. This sense of explanation is connected with …Read more
  •  29
    Would two dimensions be world enough for spacetime?
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 63 100-113. 2018.
    We consider various curious features of general relativity, and relativistic field theory, in two spacetime dimensions. In particular, we discuss: the vanishing of the Einstein tensor; the failure of an initial-value formulation for vacuum spacetimes; the status of singularity theorems; the non-existence of a Newtonian limit; the status of the cosmological constant; and the character of matter fields, including perfect fluids and electromagnetic fields. We conclude with a discussion of what cons…Read more
  •  28
    _ The Logic in Philosophy of Science _, by HalvorsonHans. Cambridge: Cambridge University Press, 2019. Pp. viii + 296.
  •  28
    Regarding the ‘Hole Argument’
    British Journal for the Philosophy of Science 69 (2): 329-350. 2018.
    I argue that the hole argument is based on a misleading use of the mathematical formalism of general relativity. If one is attentive to mathematical practice, I will argue, the hole argument is blocked. _1._ Introduction _2._ A Warmup Exercise _3._ The Hole Argument _4._ An Argument from Classical Spacetime Theory _5._ The Hole Argument Revisited
  •  25
    A classic result in the foundations of Yang-Mills theory, due to J. W. Barrett ["Holonomy and Path Structures in General Relativity and Yang-Mills Theory." Int. J. Th. Phys. 30, ], establishes that given a "generalized" holonomy map from the space of piece-wise smooth, closed curves based at some point of a manifold to a Lie group, there exists a principal bundle with that group as structure group and a principal connection on that bundle such that the holonomy map corresponds to the holonomies …Read more
  •  25
    What Is a Singularity in Geometrized Newtonian Gravitation?
    Philosophy of Science 81 (5): 1077-1089. 2014.
    I discuss singular space-times in the context of the geometrized formulation of Newtonian gravitation. I argue first that geodesic incompleteness is a natural criterion for when a model of geometrized Newtonian gravitation is singular, and then I show that singularities in this sense arise naturally in classical physics by stating and proving a classical version of the Raychaudhuri-Komar singularity theorem
  •  24
    Endogenous epistemic factionalization
    with Cailin O’Connor
    Synthese 1-22. forthcoming.
    Why do people who disagree about one subject tend to disagree about other subjects as well? In this paper, we introduce a model to explore this phenomenon of ‘epistemic factionization’. Agents attempt to discover the truth about multiple propositions by testing the world and sharing evidence gathered. But agents tend to mistrust evidence shared by those who do not hold similar beliefs. This mistrust leads to the endogenous emergence of factions of agents with multiple, highly correlated, polariz…Read more