A review of recent work on physicalism, focusing on what it means to say nothing exists over and above the physical, how "the physical" should be defined, and the causal argument for physicalism.

As a first pass, physicalism is the doctrine that there is nothing over and above the physical. Much recent philosophical work has been devoted to spelling out what this means in more rigorous terms and to assessing the case for the view. What follows is a survey of such work. I begin by looking at competing accounts of what is meant by nothing over and above and then turn to how the physical should be understood. Once we are clear on (...) the options for formulating the physicalist thesis, we will look at the leading argument for the view. Along the way, I will suggest avenues for further exploration. (shrink)

Since Leibniz's time, Cartesian mental causation has been criticized for violating the conservation of energy and momentum. Many dualist responses clearly fail. But conservation laws have important neglected features generally undermining the objection. Conservation is _local_, holding first not for the universe, but for everywhere separately. The energy in any volume changes only due to what flows through the boundaries. Constant total energy holds if the global summing-up of local conservation laws converges; it probably doesn't in reality. Energy conservation holds (...) if there is symmetry, the sameness of the laws over time. Thus, if there are time-places where symmetries fail due to nonphysical influence, conservation laws fail there and then, while holding elsewhere, such as refrigerators and stars. Noether's converse first theorem shows that conservation laws imply symmetries. Thus conservation trivially nearly entails the causal closure of the physical. But expecting conservation to hold in the brain simply assumes the falsehood of Cartesianism. Hence Leibniz's objection begs the question. Empirical neuroscience is another matter. So is Einstein's General Relativity: far from providing a loophole, General Relativity makes mental causation _harder_. (shrink)

The conservation laws do not establish the central premise within the argument from causal overdetermination – the causal completeness of the physical domain. Contrary to David Papineau, this is true even if there is no non-physical energy. The combination of the conservation laws with the claim that there is no non-physical energy would establish the causal completeness principle only if, at the very least, two further causal claims were accepted. First, the claim that the only way that something non-physical could (...) affect a physical system is by affecting the amount of energy or momentum within it, or redistributing the energy and momentum within it. Second, the claim that redistribution of energy and momentum cannot be brought about without supplying energy or momentum. Both of these claims, however, are exceedingly difficult to defend in the context of the argument. (shrink)

The Exclusion Argument for physicalism maintains that since (1) every physical effect has a sufficient physical cause, and (2) cases of causal overdetermination are rare, it follows that if (3) mental events cause physical events as frequently as they seem to, then (4) mental events must be physical in nature. In defence of (1), it is sometimes said that (1) is supported if not entailed by conservation laws. Against this, I argue that conservation laws do not lend sufficient support to (...) (1) to render its denial ‘unscientific’, and that those who accept (3) and deny (4) may consequently respond to the Exclusion Argument by denying (1) without thereby setting themselves at odds with current science. I also argue that conservation laws are compatible with (3) and the negation of (4), and that one can therefore accept conservation laws and (3) while denying both (1) and (4). (shrink)