•  560
    Plantinga on Providence and Physics
    European Journal for Philosophy of Religion 5 (3): 19--30. 2013.
    Discussion of Alvin Plantinga's book, "Where the Conflict Really Lies"
  •  552
    What Scientific Theories Could Not Be
    Philosophy of Science 79 (2): 183-206. 2012.
    According to the semantic view of scientific theories, theories are classes of models. I show that this view -- if taken seriously as a formal explication -- leads to absurdities. In particular, this view equates theories that are truly distinct, and it distinguishes theories that are truly equivalent. Furthermore, the semantic view lacks the resources to explicate interesting theoretical relations, such as embeddability of one theory into another. The untenability of the semantic view -- as cur…Read more
  •  477
    This paper presents a simple example of first-order theories T1 and T2 such that i) T1 can be embedded in T2 and vice versa, ii) T1 posits all of the structure of T2 and vice versa, but iii) T1 and T2 are not equivalent. This shows that theories lack both the Cantor-Bernstein and co-Cantor-Bernstein properties and are neither partially ordered by the relation 'is embeddable in' nor by 'posits all of the structure of'. In addition, these results clarify the overall geography of notions of equiv…Read more
  •  422
    Theism and physical cosmology
    In Charles Taliaferro, Victoria Harrison & Stewart Goetz (eds.), Routledge Companion to Theism, . 2010.
    Physical cosmology purports to establish precise and testable claims about the origin of the universe. Thus, cosmology bears directly on traditional metaphysical claims -- in particular, claims about whether the universe has a creator (i.e. God). What is the upshot of cosmology for the claims of theism? Does big-bang cosmology support theism? Do recent developments in quantum and string cosmology undermine theism? We discuss the relations between physical cosmology to theism from both historical…Read more
  •  402
    On the nature of continuous physical quantities in classical and quantum mechanics
    Journal of Philosophical Logic 30 (1): 27-50. 2001.
    Within the traditional Hilbert space formalism of quantum mechanics, it is not possible to describe a particle as possessing, simultaneously, a sharp position value and a sharp momentum value. Is it possible, though, to describe a particle as possessing just a sharp position value (or just a sharp momentum value)? Some, such as Teller, have thought that the answer to this question is No - that the status of individual continuous quantities is very different in quantum mechanics than in classical…Read more
  •  336
    I look at the distinction between between realist and antirealist views of the quantum state. I argue that this binary classification should be reconceived as a continuum of different views about which properties of the quantum state are representationally significant. What's more, the extreme cases -- all or none --- are simply absurd, and should be rejected by all parties. In other words, no sane person should advocate extreme realism or antirealism about the quantum state. And if we focus on …Read more
  •  324
    How is spontaneous symmetry breaking possible? Understanding Wigner's theorem in light of unitary inequivalence
    with David John Baker
    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
  •  310
    Some philosophers say that in special relativity, four-dimensional stuff is invariant in some sense that three-dimensional stuff is not. I show that this claim is false.
  •  309
    Antimatter
    British Journal for the Philosophy of Science 61 (1): 93-121. 2010.
    Next SectionThe 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 system…Read more
  •  305
    The Semantic View, If Plausible, Is Syntactic
    Philosophy of Science 80 (3): 475-478. 2013.
    Halvorson argues that the semantic view of theories leads to absurdities. Glymour shows how to inoculate the semantic view against Halvorson's criticisms, namely by making it into a syntactic view of theories. I argue that this modified semantic-syntactic view cannot do the philosophical work that the original "language-free" semantic view was supposed to do
  •  269
    The Conventionality of Parastatistics
    with David John Baker and Noel Swanson
    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
  •  259
    Quine’s conjecture on many-sorted logic
    Synthese 194 (9): 3563-3582. 2017.
    Quine often argued for a simple, untyped system of logic rather than the typed systems that were championed by Russell and Carnap, among others. He claimed that nothing important would be lost by eliminating sorts, and the result would be additional simplicity and elegance. In support of this claim, Quine conjectured that every many-sorted theory is equivalent to a single-sorted theory. We make this conjecture precise, and prove that it is true, at least according to one reasonable notion of the…Read more
  •  254
    Are Rindler Quanta Real? Inequivalent Particle Concepts in Quantum Field Theory
    with Rob Clifton
    British Journal for the Philosophy of Science 52 (3): 417-470. 2001.
    Philosophical reflection on quantum field theory has tended to focus on how it revises our conception of what a particle is. However, there has been relatively little discussion of the threat to the "reality" of particles posed by the possibility of inequivalent quantizations of a classical field theory, i.e., inequivalent representations of the algebra of observables of the field in terms of operators on a Hilbert space. The threat is that each representation embodies its own distinctive concep…Read more
  •  230
    A Theological Critique of the Fine-Tuning Argument
    In Matthew A. Benton, John Hawthorne & Dani Rabinowitz (eds.), Knowledge, Belief, and God: New Insights in Religious Epistemology, Oxford University Press. pp. 122-135. 2018.
    According to the premises of the fine-tuning argument, most nomologically possible universes lack intelligent life; and the fact that ours has intelligent life is best explained by supposing it was created. However, if our universe was created, then the creator chose the laws of nature, and hence chose in favor of lifeless universes. In other words, the fine-tuning argument shows that God prefers universes without intelligent life; and the fact that our universe has intelligent life provides n…Read more
  •  225
    No place for particles in relativistic quantum theories?
    with Rob Clifton
    Philosophy of Science 69 (1): 1-28. 2002.
    David Malament (1996) has recently argued that there can be no relativistic quantum theory of (localizable) particles. We consider and rebut several objections that have been made against the soundness of Malament’s argument. We then consider some further objections that might be made against the generality of Malament’s conclusion, and we supply three no‐go theorems to counter these objections. Finally, we dispel potential worries about the counterintuitive nature of these results by showing th…Read more
  •  225
    A note on information theoretic characterizations of physical theories
    Studies in History and Philosophy of Modern Physics 35 (2): 277-293. 2003.
    Clifton, Bub, and Halvorson (CBH) have recently argued that quantum theory is characterized by its satisfaction of three fundamental information-theoretic constraints. However, it is not difficult to construct apparent counterexamples to the CBH characterization theorem. In this paper, we discuss the limits of the characterization theorem, and we provide some technical tools for checking whether a theory (specified in terms of the convex structure of its state space) falls within these limits.
  •  220
    Entanglement and Open Systems in Algebraic Quantum Field Theory
    with Rob Clifton
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 32 (1): 1-31. 2001.
    Entanglement has long been the subject of discussion by philosophers of quantum theory, and has recently come to play an essential role for physicists in their development of quantum information theory. In this paper we show how the formalism of algebraic quantum field theory (AQFT) provides a rigorous framework within which to analyse entanglement in the context of a fully relativistic formulation of quantum theory. What emerges from the analysis are new practical and theoretical limitations on…Read more
  •  220
    Characterizing quantum theory in terms of information-theoretic constraints
    with Rob Clifton and Jeffrey Bub
    Foundations of Physics 33 (11): 1561-1591. 2002.
    We show that three fundamental information-theoretic constraints -- the impossibility of superluminal information transfer between two physical systems by performing measurements on one of them, the impossibility of broadcasting the information contained in an unknown physical state, and the impossibility of unconditionally secure bit commitment -- suffice to entail that the observables and state space of a physical theory are quantum-mechanical. We demonstrate the converse derivation in part, a…Read more
  •  216
    Complementarity of representations in quantum mechanics
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 35 (1): 45-56. 2004.
    We show that Bohr's principle of complementarity between position and momentum descriptions can be formulated rigorously as a claim about the existence of representations of the CCRs. In particular, in any representation where the position operator has eigenstates, there is no momentum operator, and vice versa. Equivalently, if there are nonzero projections corresponding to sharp position values, all spectral projections of the momentum operator map onto the zero element.
  •  213
    A critical examination of John Bell's article "Subject and object"
  •  210
    A sentence's meaning may depend on the state of motion of the speaker. I argue that this context-sensitivity blocks the inference from special relativity to four-dimensionalism.
  •  205
    Jill North argues that Hamiltonian mechanics provides the most spare -- and hence most accurate -- account of the structure of a classical world. We point out some difficulties for her argument, and raise some general points about attempts to minimize structural commitments
  •  192
    I give a simple proof of the folklore result that quantum mechanics has no time observable.
  •  192
    Reconsidering Bohr's reply to EPR
    with Rob Clifton
    In T. Placek & J. Butterfield (eds.), Non-locality and Modality, Kluwer Academic Publishers. pp. 3--18. 2001.
    Although Bohr's reply to the EPR argument is supposed to be a watershed moment in the development of his philosophy of quantum theory, it is difficult to find a clear statement of the reply's philosophical point. Moreover, some have claimed that the point is simply that Bohr is a radical positivist. In this paper, we show that such claims are unfounded. In particular, we give a mathematically rigorous reconstruction of Bohr's reply to the _original_ EPR argument that clarifies its logical struct…Read more
  •  190
    The purpose of this paper is to examine in detail a particularly interesting pair of first-order theories. In addition to clarifying the overall geography of notions of equivalence between theories, this simple example yields two surprising conclusions about the relationships that theories might bear to one another. In brief, we see that theories lack both the Cantor-Bernstein and co-Cantor-Bernstein properties.
  •  176
    Glymour and Quine on Theoretical Equivalence
    Journal of Philosophical Logic 45 (5): 467-483. 2016.
    Glymour and Quine propose two different formal criteria for theoretical equivalence. In this paper we examine the relationships between these criteria.
  •  176
    This dissertation reconsiders some traditional issues in the foundations of quantum mechanics in the context of relativistic quantum field theory (RQFT); and it considers some novel foundational issues that arise first in the context of RQFT. The first part of the dissertation considers quantum nonlocality in RQFT. Here I show that the generic state of RQFT displays Bell correlations relative to measurements performed in any pair of spacelike separated regions, no matter how distant. I also show…Read more
  •  173
    Many of the "counterintuitive" features of relativistic quantum field theory have their formal root in the Reeh-Schlieder theorem, which in particular entails that local operations applied to the vacuum state can produce any state of the entire field. It is of great interest then that I.E. Segal and, more recently, G. Fleming (in a paper entitled "Reeh-Schlieder meets Newton-Wigner") have proposed an alternative "Newton-Wigner" localization scheme that avoids the Reeh-Schlieder theorem. In this …Read more