This paper presents a simple pair of first-order theories that are not definitionally (nor Morita) equivalent, yet are mutually conservatively translatable and mutually 'surjectively' translatable. We use these results to clarify the overall geography of standards of equivalence and to show that the structural commitments that theories make behave in a more subtle manner than has been recognized.

Kierkegaard's Either-Or is a book about the choice between aesthetic, ethical, and religious approaches to life. I show that Either-Or also contains a proposal for philosophy of science, and in particular, about the ideal epistemic state for human beings. Whereas the Cartesian-Hegelian tradition conceived of the ideal state as one of detached deliberation -- i.e. "seeing the world as it is in itself" -- Kierkegaard envisions the ideal state as the achievement of equilibrium between the "spectator" and "actor" aspects of (...) the human being. Kierkegaard's proposal thus sets the stage for Niels Bohr's "epistemological lesson of quantum mechanics". (shrink)

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 (...) the reasonable views, it's no longer clear who counts as a realist, and who counts as an antirealist. Among those taking a more reasonable intermediate view, we find figures such as Bohr and Carnap -- in stark opposition to the stories we've been told. (shrink)

Each many-sorted theory can be converted to an unsorted theory. But this conversion procedure is not uniquely determined, leading to a dilemma: which unsorted theory captures the content of the corresponding many-sorted theory?

The thesis of quantifier variance is consistent and cannot be refuted via a collapse argument.

The hole argument purportedly shows that spacetime substantivalism implies a pernicious form of indeterminism. We show that the argument is seductive only because it mistakes a trivial claim (viz. there are isomorphic models) for a significant claim (viz. there are hole isomorphisms). We prove that the latter claim is false -- thereby closing the debate about whether substantivalism implies indeterminism.

Max Jammer claimed that, "There can be no doubt that the Danish precursor of modern existentialism and neo-orthodox theology, Soren Kierkegaard, through his influence on Bohr, affected also the course of modern physics to some extent." Despite Jammer's failure to supply sufficient evidence for this claim, I argue that it is not completely off base. In particular, I argue that Kierkegaard and Bohr belong to a common philosophical tradition, and I begin to investigate some of the themes that characterize this (...) tradition. (shrink)

A brief review of Carnap's formal program in philosophy of science.

Brief discussion of Niels Bohr's place in the history of philosophy (including his philosophical forebears, Søren Kierkegaard, Rasmus Nielsen, and Harald Høffding).

This three-part paper comprises: (i) a critique by Halvorson of Bell’s (1973) paper ‘Subject and Object’; (ii) a comment by Butterfield; (iii) a reply by Halvorson. An Appendix gives the passage from Bell that is the focus of Halvorson’s critique.

We give a simple proof that there is no time in a quantum world.

I argue against the claim -- advocated by Albert Einstein, Bernard Williams, and Ted Sider, among others -- that a description is objective only if it says how the world is in itself. Instead, I argue for the claim -- inspired by comments of Niels Bohr -- that a family of descriptions is objective only if they co-vary with their respective descriptive contexts. Moreover, I claim that "there is a shared objective reality" simply means that it is possible to satisfy (...) this kind of covariance requirement. (shrink)

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.

A short note on why we use complex numbers in physics.

Discussion of Alvin Plantinga's book, "Where the Conflict Really Lies".

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.

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.

Everyone will find something interesting in this book, and many will find something or other that they completely disagree with. William Demopoulos was no fan o.