Barry Loewer

My primary focus in this paper is on an objection to Humean account of laws and specifically to David Lewis’ “best systems analysis” (BSA). The objection is that the laws according to the BSA (which I call L-laws) fail to account for the ability of laws to explain. In contrast governing laws (which I will call G-laws) are alleged to account for the role of laws in scientific explanations by virtue of their governing role. If governing is required for laws to be explanatory then Humean accounts like Lewis’ are dead in the water since explanation is central to the role of laws in the sciences. However, I will argue that there are effective rebuttals to arguments that Humean laws don’t explain and that actually it is governing accounts that have difficulty with explanation.

This paper develops an account of the metaphysics of fundamental laws I call “the Package Deal Account ” that is a descendent of Lewis’ BSA but differs from it in a number of significant ways. It also rejects some elements of the metaphysics in which Lewis develops his BSA. First, Lewis proposed a metaphysical thesis about fundamental properties he calls “Humean Supervenience” according to which all fundamental properties are instantiated by points or point sized individuals and the only fundamental relations are geometrical spatial and temporal relations between these. While the BSA does not require HS Lewis seems to hope that it is true. In contrast, the PDA is not committed to HS or even to the fundamental arena in which fundamental properties are instantiated possessing geometrical structure and thus is able to accommodate relations and structures found in contemporary physics that apparently conflict with HS. Second, although Lewis’ BSA doesn’t require HS his Humeanism does require that fundamental properties are categorical. In contrast, the PDA allows for the possibility that fundamental properties are individuated in terms of laws and so are not categorical. Third, the PDA expands and develops the criteria for what counts in favor of a candidate system with more attention to the criteria employed by physicists in evaluating proposed theories. Fourth and most importantly, unlike Lewis’ BSA, the PDA does not presuppose metaphysically primitive elite properties/quantities that Lewis calls “perfectly natural” properties/quantities or presuppose a metaphysically preferred language whose terms denote such properties/quantities. It replaces Lewis’ account with an account on which natural properties are not metaphysically prior to the laws but are elements of a package that includes a fundamental arena that plays the role of space-time as well as fundamental laws and properties. By doing so it responds to some epistemological and metaphysical issues that have been raised regarding natural properties and their role in the BSA. In sum, the PDA goes further in explicating the notion of laws in terms of the aims and practices of science especially fundamental physics rather than in terms of prior metaphysics. I begin by reviewing Lewis’ account of perfectly natural properties and his Humean BSA of laws.

In _A Companion to David Lewis_, Barry Loewer and Jonathan Schaffer bring together top philosophers to explain, discuss, and critically extend Lewis's seminal work in original ways. Students and scholars will discover the underlying themes and complex interconnections woven through the diverse range of his work in metaphysics, philosophy of language, logic, epistemology, philosophy of science, philosophy of mind, ethics, and aesthetics. The first and only comprehensive study of the work of David Lewis, one of the most systematic and influential philosophers of the latter half of the 20th century Contributions shed light on the underlying themes and complex interconnections woven through Lewis's work across his enormous range of influence, including metaphysics, language, logic, epistemology, science, mind, ethics, and aesthetics Outstanding Lewis scholars and leading philosophers working in the fields Lewis influenced explain, discuss, and critically extend Lewis's work in original ways An essential resource for students and researchers across analytic philosophy that covers the major themes of Lewis's work

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.

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.

According to leibniz, Descartes' ontological argument establishes that if God possibly exists then God exists. To complete the argument a proof that God possibly exists is required. Leibniz attempts a proof-Theoretic demonstration that 'god exists' is consistent and concludes from this that 'god possibly exists is true'. In this paper I formalize leibniz's argument in a system of modal logic. I show that a principle which leibniz implicitly uses, 'if a is consistent then a is possibly true' is either mistaken or useless in completing the ontological argument