Completeness of physics

In this paper, I will be investigating the extent to which there are such treatments, and whether the applications that are available can figure as evidence for the completeness of physics. In the next two sections, therefore, I will examine the role of completeness as an element in the various physicalist positions, and also in arguments for these positions. I will then go on to assess some of the evidence for completeness itself. Very briefly, my overall argument with respect to the latter is as follows ... 

Papineau s version of the completeness of physics concerns the science of physics, while Kim s version concerns the causal relations which are its subject matter. The relation comes via Papineau s contention that the science of physics aims at completeness, in the sense that the causal processes it describes—or in the ideal limit of physical inquiry would describe—are closed with respect to the non-physical there are no causal factors which are not described by physics, or for whose description physics defers to another science. In this respect, physics is, he argues, quite different from, for instance, meteorology, chemistry, biology, and psychology, all of which admit external causal factors. 

The failure of Pure Mechanism on account of the existence of irreducibly macroscopic qualities need not bear directly on the completeness of physics. It may be possible, after all, that the mechanistic laws governing the interactions of microscopic particles are causally complete, and the macroscopic qualities consequently causally inert with respect to the behavior of systems of microscopic particles. Broad seems to have been aware of this possibility, for given the assumption that sensible objects really do have the irreducibly different sensible qualities they appear to have,7... 

Note, however, that Kim s property identities are in themselves insufficient to rule out downward causation. What is required in addition is the causal completeness of physics with respect to systems within which the physical properties that realize these second-order properties are instantiated. 

The first two claims characterize a physicalist worldview, or what I call physicalism. Condition (r) expresses the physicalist idea that all God needed to do to make the universe is to distribute the fundamental physical properties in space and time and make the laws of fundamental physics. All facts about macroscopic objects, their colors and behaviors, and facts about people, their thoughts and experiences, and truths about causation and the special sciences, and so on are metaphysically entailed by the fundamental physical facts and laws. Condition (2) says that the physical laws are closed and complete in the sense that, given the complete fundamental physical state at t and the laws, whether or not E occurs at t, or its chance of occurring, is completely determined. 1 assume that whatever causation is, condition (2) implies the casual completeness of physics in that E t ) s physical causes at t are sufficient to determine its occurrence (or the chances of its occurrence). Condition (2) is a consequence of (r), and it is possible to derive (r) from (2) and some other plausible premises, but I separate them since nomological and causal closure will figure importantly in our discussion. ... 

Kim then appeals to a principle he calls Closure (what we earlier called the causal completeness of physics ) ... 

Insofar as Hendry s theory of emergence focuses on entities, it is at odds not only with reductionism, but also with the causal closure or completeness of physics - the thesis that all physical events are determined (or have their chances determined) entirely by prior physical events according to physical laws (Papineau 1990, p. 67). This is because on Hendry s view, molecules are capable of downward causation. So if the theory of emergence advocated by Hendry is true, the set of physical causes must be supplemented with sui generis chemical causes - molecules exerting downward causation on their parts. 

Functional emergence need not be committed to the emergence of entities, or to their ability to exert downward causation it is committed solely to the emergence of properties, laws, and explanations. As a result, there need not be any conflict with the completeness of physics functional emergence and the completeness of physics can peacefully coexist. 

Hendry RF (2003) Chemistry and the completeness of physics. In Rojszczak A, Cachro J, Kurczewski G (eds) Philosophical dimensions of logic and science. Kluwer, Dordrecht,... 

Turing AM (1950) Computing machinery and intelligence. Mind 59(236) 433-460 Vicente A (2006) On the causal completeness of physics. Int Stud Philos Sci 20(2) 149-171 Woolley R, Sutcliffe B (1977) Molecular structure and the Bom-Oppenheimer approximation. Chem Phys Lett 45 393-398... 

Spurrett, David, and David Papineau. 1999. A note on the completeness of physics . Analysis 59 25-28. 

Why should every physicalist be committed to the completeness of physics Perhaps physicalism of one sort or another can be argued for on independent grounds, with the completeness claim dropping out as a corollary. However, the completeness of physics typically appears as a lemma. In 1966, Lewis, arguing for (a restricted) type-identity of mental and physical, was explicit about his appeal to the completeness of physics, and the empirical nature of that claim ... 

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