Defending 'A Conceptual Investigation of Justice'

In this paper, I explain the arguments my critics target and I respond to their criticisms. Some of my replies further expand upon the ideas covered in my book—'A Conceptual Investigation of Justice'—and some cover matters that weren’t discussed there. This paper thus substantially contributes to the arguments made in my book

Conceptual Disagreement about Justice: Verbal, but Not Merely Verbal

In this paper, I introduce the articles contained in this special issue, and I briefly explain some of the main arguments presented in my book 'A Conceptual Investigation of Justice'. A central claim in my book is that a verbal and yet also philosophically substantial disagreement over the word ‘justice’ lies at the heart of a number of issues in contemporary political philosophy. Over the course of introducing my book’s arguments and the commentaries in this issue, I also offer an account of what it means for a dispute to be verbal, but not merely verbal

A Ray-Tracing Algorithm for Spinning Compact Object Spacetimes with Arbitrary Quadrupole Moments. I. Quasi-Kerr Black Holes

We describe a new numerical algorithm for ray tracing in the external spacetimes of spinning compact objects characterized by arbitrary quadrupole moments. Such spacetimes describe non-Kerr vacuum solutions that can be used to test the no-hair theorem in conjunction with observations of accreting black holes. They are also appropriate for neutron stars with spin frequencies in the 300-600 Hz range, which are typical of the bursting sources in low-mass X-ray binaries. We use our algorithm to show that allowing for the quadrupole moment of the spacetime to take arbitrary values leads to observable effects in the profiles of relativistic broadened fluorescent iron lines from geometrically thin accretion disks.Comment: submitted to the Astrophysical Journa

Cohen's Equivocal Attack on Rawls's Basic Structure Restriction

G.A. Cohen is famous for his critique of John Rawls’s view that principles of justice are restricted in scope to institutional structures. In recent work, however, Cohen has suggested that Rawlsians get more than just the scope of justice wrong: they get the concept wrong too. He claims that justice is a fundamental value, i.e. a moral input in our deliberations about the content of action-guiding regulatory principles, rather than the output. I argue here that Cohen’s arguments for extending the scope of justice equivocate across his distinction between fundamental principles of justice, i.e. principles that tell us what justice is; and regulatory principles of justice, i.e. principles that tell us what is required of us, all things – including justice – considered. Though Cohen initially had the regulatory sense of the word ‘justice’ in mind when critiquing the basic structure restriction, his replies to the problem of demandingness presuppose his own, fundamental sense of the word ‘justice’. The upshot is that he escapes demandingness at the cost of sacrificing regulatory justice’s capacity to provide clear guidance. I conclude by considering Peter Singer’s efforts to deal with demandingness in his own work on global poverty. Since Singer manages to deal with demandingness without giving up clarity, his work is a good a place to start in the search for regulatory principles that are suitable for the context of personal choice

Constraints on the Size of Extra Dimensions from the Orbital Evolution of the Black-Hole X-Ray Binary XTE J1118+480

In a universe of the Randall-Sundrum type, black holes are unstable and emit gravitational modes in the extra dimension. This leads to dramatically shortened lifetimes of astrophysical black holes and to an observable change of the orbital period of black-hole binaries. I obtain an upper limit on the rate of change of the orbital period of the binary XTE J1118+480 and constrain the asymptotic curvature radius of the extra dimension to a value that is of the same order as the constraints from other astrophysical sources. A unique property of XTE J1118+480 is that the expected rate of change of the orbital period due to magnetic braking alone is so large that only one additional measurement of the orbital period would lead to the first detection of orbital evolution of a black-hole binary and impose the tightest constraint to date on the size of one extra dimension of the order of 35 microns.Comment: accepted for publication in A&

Are Some Animals Also Moral Agents?

Animal rights philosophers have traditionally accepted the claim that human beings are unique, but rejected the claim that our uniqueness justifies denying animals moral rights. Humans were thought to be unique specifically because we possess moral agency. In this commentary, I explore the claim that some nonhuman animals are also moral agents, and I take note of its counter-intuitive implications