Barry Loewer

Among the most important questions in the metaphysics of science are "What are the natures of fundamental laws and chances?" and "What grounds the direction of time?" My aim in this paper is to examine some connections between these questions, discuss two approaches to answering them and argue in favor of one. Along the way I will raise and comment on a number of issues concerning the relationship between physics and metaphysics and consequences for the subject matter and methodology of metaphysics

The most important theories in fundamental physics, quantum mechanics and statistical mechanics, posit objective probabilities or chances. As important as chance is there is little agreement about what it is. The usual “interpretations of probability” give very different accounts of chance and there is disagreement concerning which, if any, is capable of accounting for its role in physics. David Lewis has contributed enormously to improving this situation. In his classic paper “A Subjectivist's Guide to Objective Chance” he described a framework for representing single case objective chances, showed how they are connected to subjective credences, and sketched a novel account what they are within his Humean account of scientific laws. Here I will describe these contributions and add a little to them.

NRP is a family of views differing by how they understand “reduction” and “physicalism.” Following Kim I understand the non-reduction as holding that some events and properties are distinct from any physical events and properties. A necessary condition for physicalism is that mental properties, events, and laws supervene on physical ones. Kim allows various understandings of “supervenience” but I think that physicalism requires at least the claim that any minimal physical duplicate of the actual world is a duplicate simpliciter. Some complications aside this means that true mental propositions, e.g. Jaegwon is thinking about sailing, are metaphysically entailed by true physical propositions. Kim says that supervenience is too weak to capture the root idea of physicalism that mental property instantiations depend on physical property instantiations so he adds that the mental depends on the physical. One way in which this dependance might be spelled out is that mental properties are higher order functional properties whose instantiations are realized by instantiations of physical properties. An event is an instantiation of a property by an individual and a time. A mental event is the instantiation of a mental property. Not every predicate expresses a genuine property. Kim further suggests that properties are individuated, at least partly, by nomological and causal relations. For physicalism to have content something must be said about the difficult issue of characterizing the physical. Kim’s view seems to be that the micro-physical properties of ideal physics are physical. He also counts as physical properties that are conjunctions and aggregates of micro-physical properties and higher level properties defined over lower-level physical properties.. Since these latter two classes of properties supervene on the micro-properties and laws there is no need to include them in the supervenience base.