Tuesday, July 17, 2007

Powers and Property Dualism

Powers (or dispositional properties) are the centerpiece of George Molnar’s causal realist metaphysical model. The following question arises: are powers the only sort of property, or are there others?

Molnar considers whether powers (with the features he ascribes to them) could be the star players in an ontological monism (called pan-dispositionalism). It would seem that adopting pan-dispositionalism, along with the natural assumption that manifestations of dispositions constitute changes in the properties of objects, leads to a regress. Powers only manifest as changes to other powers. But is this a vicious regress? Molnar considers a couple of arguments that it is indeed vicious. If objects are things which take up space, then powers need to be joined by space occupying properties in order to constitute objects. But a look at particle physics seems to show that elementary constituents of nature do not have volume or occupy space in the way common sense implies. So this doesn’t seem to be a convincing objection – it’s not clear that objects need “space-occupying” non-power properties. A second objection says that objects need to have non-power properties which are qualities. But are there mind-independent physical qualities? What are they? Candidates such as size, shape, color are all phenomenological, rather than fundamentally physical, according to Molnar.

Molnar doesn’t see that the regress objections are fatal, but nevertheless concludes pan-dispositionalism is unlikely to be true for a posteriori reasons. Since powers are intrinsic to objects (in his theory), he considers the reality that they are “portable”. They are not necessarily altered if I move the object somewhere else. He sees the need for non-powers which are responsible for what scientists call symmetry operations (hence “S-properties”). These are essentially positional properties (positions in space-time) with one exception – if parts of a complex object have identical powers, and they exchange roles (say swapping the two hydrogen atoms in a water molecule), the powers of the complex object are not affected. This is a property of numerical identity.

So, Molnar does end up with a property dualism. There are powers, which are intrinsic dispositions of objects; and there are non-powers, which are extrinsic and basically have to do with placement of objects in space-time.

Certainly, as property dualisms go, this is a pretty bare bones version compared to what the term “dualism” usually connotes. On the other hand, while Molnar is presenting a pretty ambitious metaphysical system, he is not trying to explain the mind, which is what traditionally motivates dualistic theories.

One critique I have centers on Molnar’s reliance throughout on his interpretations of physics. Powers are deemed intrinsic because, for instance, charge seems like an irreducible property of an electron. He says qualitative properties like size and shape don’t exist, because they do not feature in physics. He argues positional properties make sense because of symmetry operations which can be conducted on physical systems. A mostly unstated but crucial assumption underlying all of this is a somewhat old-fashioned view that physics supports the conception of objects moving around in a static space-time container. So a theory of powers which is motivated largely by a priori analysis of causation has its details shaped by these a posteriori inputs from physics. There are a couple of obvious concerns: first that his interpretations of physical theories may be incorrect, and second, that the theories he’s interpreting are provisional and may be superseded.

We don’t have a final theory of physics yet, but we can make an educated guess that the conception of objects moving in a space-time container (already extremely distorted in quantum field theory) will not survive. In General Relativity, there is a dynamic interaction between space-time and matter fields, and this seems to compromise the separation of properties into powers and positional properties (doesn’t a dynamic space-time need powers, too?). Further, in some quantum gravity research programs (my favorite ones), both space-time and matter fields are seen as emerging from a more fundamental basis (specifically a causal network of quantum mechanical interactions).

Still, the idea that positional properties are needed seems right to me. The nature of quantum mechanical propensities appears to depend on the relation between quantum systems. In a theory featuring a causal network of quantum mechanical interactions, causation would depend both on propensities (powers) and position in the network. One thing I think we could drop altogether is the idea of an object. What we think of as objects would be complex patterns of causal events in this way of thinking.


Antonio Franco said...

Dear Steve,
You might have already read it. In case not, there is an interesting paper by Stathis Psillos "What Do Powers Do When Thwy Are Not Manifested?", available online in his webpage (http://www.phs.uoa.gr/~psillos/). He comments on Molnar's, and also McKitrick's view of powers (as dispositions), proposing instead a more law(or regularity)-like view, which he considers to fare better with the suggestions of modern physics.

I think that Rosenberg's theory also favours dispositions (in the dual aspect of effective and receptive properties) as the basic stuff underlying 'reality'. By the way, McKitrick makes some criticism of this view of dispositions as relational properties in her paper "Rosenberg on Causation" (http://psyche.es.monash.edu.au/symposia/rosenberg/McKitrick.pdf). But perhaps, I think, when diving deep in that bare stuff underlying 'reality' there is not actually so much difference between powers (=dispositions) and laws or regularities, and there might be some kind of basic convergence.

With reference to some of the discussions you are having here, McKitrick also criticizes Rosenberg's theory on the issue of 'mental causation'. I recognize that this point also remains a bit obscure to me in my reading of Rosenberg's book. Of course, Rosenberg disapproves of interactionism, but I wonder if his view doesn't fall then too close to epiphenomenalism. I probably miss a more detailed account on this matter.

In any case, I think those papers are worth reading even if one doesn't share their conclusions.

Thanks again for provoking new insights and reflections through your excellent blog.

Steve said...

Thank you Antonio.
I will read that Psillos paper. I think laws are derived/emergent and causation is fundamental, but I'm always interested in challenging my views.

I was happy to read McKitrick's article in Psyche awhile back. She made a good in-depth attempt to understand and critique Rosenberg's model of causation. I didn't write up my comments because I thought Gregg Rosenberg might respond and I wanted to see that first -- but he is very busy with his private sector pursuits. Some of her criticisms resulted from missing the point a bit (especially in the case of the abstract modal realism aspect of the model), but I thought her criticism of the connective dimension of receptive properties was perceptive.

I don't think interactionism or epiphenomenalism are right. My view, and I think Rosenberg's, is that experience is an irreducible aspect of each and every causal event which comprises the world. While it may be that a property dualism of a sort is needed to characterize how the causal network works, I think our concepts of mental and physical are epistemic, not ontological categories (same events viewed from particpatory first-person perspective in the first case and described in the third person in the other).

Best regards,
- Steve