Princeton University
Department of Philosophy
PhD, 2009
Ann Arbor, Michigan, United States of America
Areas of Specialization
Philosophy of Physical Science
  •  43
    What Are Symmetries?
    Ergo: An Open Access Journal of Philosophy 9 (n/a). 2022.
    I advance a stipulational account of symmetry-to-reality inference, according to which symmetries are part of the content of theories. For a theory to have a certain symmetry is for the theory to stipulate that models related by the symmetry represent the same possibility. I show that the stipulational account compares positively with alternatives, including Dasgupta’s epistemic account of symmetry, Møller-Nielsen’s motivational account, and so-called formal and ontic accounts. In particular, th…Read more
  •  287
    The Conventionality of Parastatistics
    British Journal for the Philosophy of Science 66 (4): 929-976. 2015.
    Nature seems to be such that we can describe it accurately with quantum theories of bosons and fermions alone, without resort to parastatistics. This has been seen as a deep mystery: paraparticles make perfect physical sense, so why don’t we see them in nature? We consider one potential answer: every paraparticle theory is physically equivalent to some theory of bosons or fermions, making the absence of paraparticles in our theories a matter of convention rather than a mysterious empirical disco…Read more
  •  10
  •  359
    How is spontaneous symmetry breaking possible? Understanding Wigner's theorem in light of unitary inequivalence
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 44 (4): 464-469. 2013.
    We pose and resolve a puzzle about spontaneous symmetry breaking in the quantum theory of infinite systems. For a symmetry to be spontaneously broken, it must not be implementable by a unitary operator in a ground state's GNS representation. But Wigner's theorem guarantees that any symmetry's action on states is given by a unitary operator. How can this unitary operator fail to implement the symmetry in the GNS representation? We show how it is possible for a unitary operator of this sort to con…Read more
  •  20
    Knox’s inertial spacetime functionalism
    Synthese 199 (Suppl 2): 1-22. 2020.
    Eleanor Knox has argued that our concept of spacetime applies to whichever structure plays a certain functional role in the laws. I raise two objections to this inertial functionalism. First, it depends on a prior assumption about which coordinate systems defined in a theory are reference frames, and hence on assumptions about which geometric structures are spatiotemporal. This makes Knox’s account circular. Second, her account is vulnerable to several counterexamples, giving the wrong result wh…Read more
  •  17
    Comments and replies from the 2021 Eastern APA book symposium on Jill North's Physics, Structure, and Reality.
  •  9
    Comparativism--the view that comparative relations like mass ratios are fundamental and intrinsic values of quantities are not--faces a challenge from physics. In its standard form, comparativism predicts indeterminism in physical theories that are ordinarily understood as deterministic. I explore an option for saving comparativism from this objection: the introduction of "mixed" relations that compare values of unlike quantities. Although tenable, this revised version of comparativism lacks som…Read more
  •  25
    A new argument is given for the thesis that only symmetry-invariant physical quantities are real. Non-invariant quantities are dynamically epiphenomenal in that they have no effect on the evolution of invariant quantities, and it is a significant theoretical vice to posit epiphenomenal quantities.
  •  25
    Knox’s inertial spacetime functionalism
    Synthese 199 (S2): 277-298. 2020.
    Eleanor Knox has argued that our concept of spacetime applies to whichever structure plays a certain functional role in the laws. I raise two objections to this inertial functionalism. First, it depends on a prior assumption about which coordinate systems defined in a theory are reference frames, and hence on assumptions about which geometric structures are spatiotemporal. This makes Knox’s account circular. Second, her account is vulnerable to several counterexamples, giving the wrong result wh…Read more
  •  329
    Antimatter
    British Journal for the Philosophy of Science 61 (1): 93-121. 2010.
    The nature of antimatter is examined in the context of algebraic quantum field theory. It is shown that the notion of antimatter is more general than that of antiparticles. Properly speaking, then, antimatter is not matter made up of antiparticles—rather, antiparticles are particles made up of antimatter. We go on to discuss whether the notion of antimatter is itself completely general in quantum field theory. Does the matter–antimatter distinction apply to all field theoretic systems? The answe…Read more
  •  203
    I consider an argument, due to Geoffrey Lee, that we can know a priori from the left-right asymmetrical character of experience that our brains are left-right asymmetrical. Lee's argument assumes a premise he calls relationism, which I show is well-supported by the best philosophical picture of spacetime. I explain why Lee's relationism is compatible with left-right asymmetrical laws. I then show that the conclusion of Lee's argument is not as strong or surprising as he makes it out to be
  •  165
    Ted Sider has shown that my indeterminism argument for comparativist theories of quantity also applies to Mundy's absolutist theory. This is because Mundy's theory posits only "pure" relations, i.e. relations between values of the same quantity (between masses and other masses, or distances and other distances). It is straightforward to solve the problem by positing additional mixed relations.
  •  68
    Interpreting Supersymmetry
    Erkenntnis 87 (5): 2375-2396. 2020.
    Supersymmetry in quantum physics is a mathematically simple phenomenon that raises deep foundational questions. To motivate these questions, I present a toy model, the supersymmetric harmonic oscillator, and its superspace representation, which adds extra anticommuting dimensions to spacetime. I then explain and comment on three foundational questions about this superspace formalism: whether superspace is a substance, whether it should count as spatiotemporal, and whether it is a necessary postu…Read more
  •  35
    Measurement outcomes and probability in Everettian quantum mechanics
    Studies in History and Philosophy of Modern Physics 38 (1): 153-169. 2006.
    The decision-theoretic account of probability in the Everett or many-worlds interpretation, advanced by David Deutsch and David Wallace, is shown to be circular. Talk of probability in Everett presumes the existence of a preferred basis to identify measurement outcomes for the probabilities to range over. But the existence of a preferred basis can only be established by the process of decoherence, which is itself probabilistic.
  •  84
    Some Consequences of Physics for the Comparative Metaphysics of Quantity
    In Karen Bennett & Dean W. Zimmerman (eds.), Oxford Studies in Metaphysics Volume 12, Oxford University Press. pp. 75-112. 2020.
    According to comparativist theories of quantities, their intrinsic values are not fundamental. Instead, all the quantity facts are grounded in scale-independent relations like "twice as massive as" or "more massive than." I show that this sort of scale independence is best understood as a sort of metaphysical symmetry--a principle about which transformations of the non-fundamental ontology leave the fundamental ontology unchanged. Determinism--a core scientific concept easily formulated in absol…Read more
  •  214
    Spacetime Substantivalism and Einstein’s Cosmological Constant
    Philosophy of Science 72 (5): 1299-1311. 2005.
    I offer a novel argument for spacetime substantivalism: We should take the spacetime of general relativity to be a substance because of its active role in gravitational causation. As a clear example of this causal behavior I offer the cosmological constant, a term in the most general form of the Einstein field equations which causes free floating objects to accelerate apart. This acceleration cannot, I claim, be causally explained except by reference to spacetime itself.
  •  53
    (No abstract is available for this citation)
  •  956
    Eleanor Knox has argued that our concept of spacetime applies to whichever structure plays a certain functional role in the laws (the role of determining local inertial structure). I raise two complications for this approach. First, our spacetime concept seems to have the structure of a cluster concept, which means that Knox's inertial criteria for spacetime cannot succeed with complete generality. Second, the notion of metaphysical fundamentality may feature in the spacetime concept, in whic…Read more
  •  137
    It is sometimes claimed that string theory posits a fundamental ontology including extended mereological simples, either in the form of minimum-sized regions of space or of the strings themselves. But there is very little in the actual theory to support this claim, and much that suggests it is false. Extant string theories treat space as a continuum, and strings do not behave like simples.
  •  50
    Review: Frank Arntzenius: Space, Time, and Stuff (review)
    Philosophical Explorations. 2013.
  •  124
    If we divide our physical theories into theories of matter and theories of spacetime, quantum field theory is our most fundamental empirically successful theory of matter. As such, it has attracted increasing attention from philosophers over the past two decades, beginning to eclipse its predecessor theory of quantum mechanics in the philosophical literature. Here I survey some central philosophical puzzles about the theory's foundations.
  •  36
    Review: Frank Arntzenius: Space, Time, and Stuff (review)
    Philosophy of Science 81 (1). 2014.
  •  147
    The permutation symmetry of quantum mechanics is widely thought to imply a sort of metaphysical underdetermination about the identity of particles. Despite claims to the contrary, this implication does not hold in the more fundamental quantum field theory, where an ontology of particles is not generally available. Although permutations are often defined as acting on particles, a more general account of permutation symmetry can be formulated using superselection theory. As a result, permutation s…Read more
  •  216
    Symmetry and the Metaphysics of Physics
    Philosophy Compass 5 (12): 1157-1166. 2010.
    The widely held picture of dynamical symmetry as surplus structure in a physical theory has many metaphysical applications. Here, I focus on its relevance to the question of which quantities in a theory represent fundamental natural properties
  •  38
    Review of Richard Healey's 2008 book. To appear in MIND.
  •  222
    Broken Symmetry and Spacetime
    Philosophy of Science 78 (1): 128-148. 2011.
    The phenomenon of broken spacetime symmetry in the quantum theory of infinite systems forces us to adopt an unorthodox ontology. We must abandon the standard conception of the physical meaning of these symmetries, or else deny the attractive “liberal” notion of which physical quantities are significant. A third option, more attractive but less well understood, is to abandon the existing (Halvorson-Clifton) notion of intertranslatability for quantum theories.
  •  298
    Measurement outcomes and probability in Everettian quantum mechanics
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 38 (1): 153-169. 2007.
    The decision-theoretic account of probability in the Everett or many-worlds interpretation, advanced by David Deutsch and David Wallace, is shown to be circular. Talk of probability in Everett presumes the existence of a preferred basis to identify measurement outcomes for the probabilities to range over. But the existence of a preferred basis can only be established by the process of decoherence, which is itself probabilistic.