Overview

I have two big projects.

1. My current work in metaphysics concerns causation and the idea of fundamental reality. I am working on a multi-volume project where I produce a new account of causation and then apply it to standard metaphysical problems like the mind-body problem, free will, the passage of time, and much more. (If you only have time to examine one paper, have a look at my recent discoveries concerning the asymmetry of influence, i.e. the idea that we influence the future but not the past.)

2. My future work in the philosophy of physics involves determining the relation between matter and spacetime. Specifically, I am looking at the CPT symmetry for clues about whether spacetime and matter are metaphysically derivative aspects of a fundamental stuff that is somehow a fusion of them.

Causation

For an extensive overview of my new book, Causation and its Basis in Fundamental Physics, take a look at the Introductory Chapter.

One of the most important arguments in the book is the explanation of the time asymmetry of causal influence. I provide a quick version of the argument in the upcoming Oxford Handbook on Time, and you can read an excerpt that has most of the core argument. Be aware that the argument here marks a significant change of my opinion about how to explain the causal asymmetry.

Empirical Analyses of Causation will be coming out in New Waves in Metaphysics (2009): Conceptual analyses can be subdivided into two classes, good and evil. Empirical analysis is the good kind, routinely practiced in the sciences. Orthodox analysis is the malevolent version that plagues philosophical discourse. In this paper, I will clarify the difference between them, provide some reasons to prefer good over evil, and illustrate their consequences for the metaphysics of causation. By conducting an empirical analysis of causation rather than an orthodox analysis, one can segregate the genuine metaphysical problems that need to be addressed from the many pseudo-problems that have long dogged traditional accounts of causation.

An Explanans for Two Facts about Causation: An event E_1 never makes an event E_2 more likely by way of a nomic connection that goes from E_1 back in time to an event C and then forward in time to E_2. Also, one can never exploit a nomic connection from an event C to a desired prior event E as a means of making E more likely. I explain these two facts using facts about fundamental dynamical laws. These facts are relatively uncontroversial because they hold for all paradigm theories of fundamental physics. Also, no assumption of a primitive temporal or causal asymmetry is made. Thus, my explanation relies on less controversial hypotheses than alternative explanations.

The Physical Foundations of Causation in Huw Price and Richard Corry, eds., Causation, Physics and the Constitution of Reality: Russell's Republic Revisited (OUP, 2007): I defend what may loosely be called an eliminativist account of causation by showing how several of the main features of causation, namely asymmetry, transitivity, and necessitation (or sometimes probability-raising), arise from the combination of fundamental dynamical laws and a special constraint on the macroscopic structure of matter in the past. At the microscopic level, the causal features of necessitation and transitivity are grounded, but not the asymmetry. At the coarse-grained level of the macroscopic physics, the causal asymmetry is grounded, but not the necessitation or transitivity. Thus, at no single level of description does the physics justify the conditions that are taken to be constitutive of causation. Nevertheless, if we mix our reasoning about the microscopic and macroscopic descriptions, the structure provided by the dynamics and special initial conditions can justify the folk concept of causation to a significant extent. I explain why our causal concept works so well even though at bottom it is comprised of a patchwork of principles that don't mesh well.

Counterfactual Conditionals and Influence

The Asymmetry of Influence: Conventional wisdom has it that we cannot affect the past. I show that conventional wisdom is incorrect. We routinely influence the past. In a sense, we influence the past more than we do the future. However, due to some basic facts about the fundamental laws of physics and other issues distantly related to entropy, it turns out that none of our influence over the past is useful for accomplishing any goals we might have for how things turned out. Like our own personal influence over the position of the Moon tomorrow or over the music preferences of people in the far distant future, our influence over the past is not of a kind that we can usefully control. Hence, we tend to overlook that we really do influence it.

Similarity is a Bad Guide to Counterfactual Truth (2006 APA Pacific Meeting): A prominent strategy for evaluating whether a counterfactual's truth is to seek out the most similar worlds where the antecedent is true, with similarity given by some theory. I discuss a few new counterexamples to Lewis' theory of overall similarity that are more compelling than other counterexamples because they indicate that a system like Lewis' cannot be fixed. The problem with the similarity approach is that it too narrowly limits the ways we can interpret counterfactual conditionals.

The Entropy Theory of Counterfactuals (2002) I assess the thesis that counterfactual asymmetries are explained by an asymmetry of the global entropy at the temporal boundaries of the universe, by developing a method of evaluating counterfactuals that includes, as a background assumption, the low entropy of the early universe. The resulting theory attempts to vindicate the common practice of holding the past mostly fixed under counterfactual supposition while at the same time allowing the counterfactual's antecedent to obtain by a natural physical development. Although the theory has some success in evaluating a wide variety of ordinary counterfactuals, it fails as an explanation of counterfactual asymmetry.

PhD Dissertation: Entropy and Counterfactual Asymmetry (with incorrect chapter numbers). The dissertation covers the material in The Entropy Theory of Counterfactuals as well as discussion of a notion of objective assertibility, and some discussion of David Lewis treatment of counterfactual asymmetry, and some other things.

Quantum Physics

A New Puzzle Concerning the Relation between Relativistic and Galilean Physics Relativistic quantum theories are equipped with a background Minkowski spacetime and non-relativistic quantum theories with a Galilean spacetime. Traditional investigations have distinguished their distinct spacetime structures and have examined ways in which relativistic theories become sufficiently like Galilean theories in a low velocity approximation or limit. A new way to look at their relationship is to see how both kinds of theories are special cases of a certain five-dimensional generalization involving no limiting procedures or approximations. When one compares them, striking features emerge that bear on philosophical questions concerning the ontological status of the wave function, the relation between mass, energy, and momentum, and non-locality.

Time Travel

Time Travel and Consistency Constraints (2001) The possibility of time travel, as permitted in General Relativity, is responsible for constraining physical fields beyond what laws of nature would otherwise require. In the special case where time travel is limited to a single object returning to the past and interacting with itself, consistency constraints can be avoided if the dynamics is continuous and the object's state space satisfies a certain topological requirement: that all null-homotopic mappings from the state-space to itself have some fixed point. Where consistency constraints do exist, no new physics is needed to enforce them. One needs only to accept certain global topological constraints as laws, something that is reasonable in any case.

This paper follows up on some of the issues in Time Travel and Modern Physics and John Earman's discussion (in Bangs, Crunches, Whimpers, and Shrieks) of the implications of time travel (in General Relativity) for notions of physical possibility.