The hidden premise in the causal argument for physicalism

1. The causal argument in favor of physicalism roughly states that all physical effects are due to physical causes, hence anything having physical effects must itself be physical (cf. Papineau 2002). A crucial premise in this argument is known variously as the ‘completeness of physics ’ or the ‘causal closure of physics ’ (CoP), which maintains, roughly, that all physical effects are fully determined by fundamental laws and prior physical events. There are a number of ways to state CoP more precisely, but the following will suffice: For any distinct times t1 and t2, the physical event e(t1) together with the fundamental physical laws causes the (chances of) physical event e(t2). Some defenders of CoP understand it as an unqualified statement to the effect that there is no room for anything other than physical events and laws to determine the evolution of physical events–that is, physical events are hermetically sealed off from any possible nonphysical influences. This is a very strong construal of CoP and is largely indistinguishable from physicalism, so cannot serve as an independent premise in the causal argument. Many defenders of CoP, however, take a weaker understanding of CoP, namely that physical effects have physical causes and that any other kinds of causes are ineffective in bringing about or influencing physical effects. This latter interpretation is how