Lower level locations (high, low, or basic physical levels)

We shall start with locations with physical properties. To make it a bit clearer what is meant by aphysicalproperty (or level), we should distinguish between two different senses of physicalism. First, there is a sense in which physicalism for a given domain entails that the disputed concepts refer to physical properties, and that the disputed properties are identical with physical properties – that colours, for example, are surface structures, or perhaps reflectance spectra. Secondly, there is a broader sense of physicalism which entails only that the disputed phenomenon is realised by, or constituted by, or supervenient on, or determined by, the physical (these hard-to- define relations will be discussed briefly in Ch. 3). The latter kind of physicalism is most interesting as aglobalthesis, often formulated along the lines of ‘if the physical facts about our world are determined, all the facts about our world are determined’ (this is a paraphrase of Chalmers 1996, p. 42), or ‘a minimal physical duplicate of our world is a duplicate simpliciter of our world’ (Jackson 1994, p. 164). By contrast, the first brand of physicalism seems most interesting in local versions, since a global claim that all terms that refer at all refer to physical properties seems highly unlikely to be true.

When I talk about low level locations in the following, I am talking about physicalism in the first sense: identification with, or location of the reference with, physical properties. Rejection of physicalism in this sense is compatible with physicalism in the second sense. One can thus be a (global) materialist without going

for a low level location in each and every location dispute, as long as one holds that all high level phenomena are physically realised, or supervene on the physical in the right way (provided that these relations are understood in a way that does not itself entail a low level location).

A first thing to notice about physical level locations is that there are many of them; for colours, for example, both surface structures and reflectance spectra are perfectly respectable physical properties. (There are even more levels to choose from if we include the properties typically treated by the other natural sciences – chemical properties, biological properties etc. – presumably these are equally natural, scientific, non-anthropocentric etc. properties, though they do not belong to the domain of physics.) Thus, a physical level location does not always mean a basic level location. This allows us to distinguish two different sorts of physical level locations: basic level locations and non-basic level ones. The former category might be empty if the idea of a basic level is illusory (more on this in Ch. 3).

A standard argument for low or basic level location isontological economy. By reducing as many seeming higher-level phenomena as possible to lower-level ones, we get fewer ontological categories, and a simpler and more unified picture of the world. Relatedly, the history of science is a history of successful reductions from higher to lower levels; what we think of as paradigmatic epistemic achievements consist in bringing this sort of order into our world view.

(Higher level theorists might dispute the relevance of these considerations by arguing that all that is needed for explanatory reductions of the relevant kind is (the right sort of) supervenience, while low level locations in the form of identity claims are not necessary. There is presumably a long and complex discussion to be had over these matters, but this thesis is not the place to have it.)

Another prominent group of arguments for low level locations is what could be

labelled causal arguments. Many such arguments are variations over the causal

exclusion argument.10 In the original version about mental states, the causal

10

Kim (1998) and various other works. The statement of the argument to follow is inspired by Crane (2001).

exclusion argument shows that there is an inconsistency across the following individually plausible claims:

1. Mental phenomena have effects in the physical world

2. All physical effects have physical causes which are sufficient to bring them about (i.e. the physical domain is causally closed)

3. Mental and physical causes do not over-determine their physical effects

4. The mental and the physical are distinct (this covers dualism in any form – everything that is not an identity theory)

Less formally, we want to say that mental phenomena do some causal work, physical phenomena do all the causal work, the two are distinct, and there is no over- determination. But we can’t have all of these claims. In the classic formulations of the argument, the invited conclusion is that mental and physical phenomena are not distinct after all.

This argument can be carried over to other areas, e.g. colours and dispositions. Versions of the argument could presumably be stated for any area in which we have multiple levels, of which the lower ones are levels of physical properties, and where the higher level properties are thought to cause physical effects. Thus, it would presumably apply to various kinds of special science causation, e.g. causal claims within biology, chemistry, and physiology.11

Note that if causal exclusion arguments do indeed apply to scientifically kosher higher level properties, e.g. biological, chemical, and higher level physical ones, the argument will count in favour of basic level locations only, whereas it will be no use as an argument for higher level locations within the physical domain. (So if there is no basic level – or if we have no independent evidence to believe in one, and refuse to take an a priori argument like the causal exclusion argument as a sign that it exists – then so much the worse for the causal exclusion argument.) Variations on the theme of causal arguments are Frank Jackson’s argument for colour physicalism and Mark Johnston’s missing explanation argument.12

11_{See e.g. Block (2003).}

12 _{For Jackson’s argument against colour physicalism, see Jackson (1998), p. 90-95. For}

2.2 Higher level locations (response-dependence, functionalism, phenomenal