Monday, May 23, 2005

The Trouble with Tropes

In this interesting post at Maverick Philosopher, Bill Vallicella explores critically the metaphysical theory that all properties in the world are tropes, which are ontologically simple building blocks (technically speaking, abstract particulars). In other words, trope theory is a one-category ontology. The key question is, then, how do these tropes come together to make things? The advocate of the view would need to propose a compresence relationship which binds tropes, but still is itself a trope of the same ontological variety. Vallicella then argues that this leads to problems, particularly a vicious regress. If the compresence trope ‘C’ links tropes ‘R’ and ‘S’ together, then what links C to both R and S? If it is another trope C*, you can see the regress. It made sense to me, although I imagine philosophers who have developed different varieties of trope theories would have a response. In any case, the arguments are carefully constructed, and I refer you to the post itself and the SEP entry on tropes for further reading.

For me, this discussion lends support to my previously held belief that a single simple ontological building block cannot account for the diversity of natural entities. A second relation is needed – a property which binds and actualizes, but is itself not in need of binding in the same way. At first, this may seem to make for a less appealingly simple or monistic ontology; however, when the property complexes that result are cast as events rather than things, the dual aspect seems to me elegant and not ad hoc, as I argued in this recent post.

Friday, May 20, 2005

More Quantum Causality

I have suspected that modern quantum theory contains the seeds of a new theory of causality. I did a search on Google scholar looking for more papers. I thought this one, by mathematical physicist V.P. Belavkin, was interesting, and I offer the briefest of summaries below. As usual, I was limited in my ability to follow the formalism, and therefore will “bleg” anyone with expertise in this area to comment or offer references which help explain this in layman’s terms.

Belavkin says that “the latest developments in quantum probability, stochastics, and in quantum information theory” make it possible to bypass the paradoxes of the measurement problem in the traditional quantum theory. The original theory divides the world into an external observer and a closed quantum system to be observed, which results in the problem.

It goes something like this: Belavkin analyzes open quantum systems using a dynamical approach which gives the output statistics of continuous quantum measurements which result from the solution of a stochastic differential equation. He then applies a special filtering method or superselection rule – which he calls a causality principle – which imposes a past-future boundary. The past consists of classical particle trajectories, the future are the quantum probabilities compatible with these trajectories. The statistical results obtained are consistent with experiment, just as in the traditional formulation.

Now it seems we haven’t gotten “something for nothing” here. In exchange for getting rid of the seemingly subjective observer problem in the original theory and making things more objective, he had to insert “by hand” a boundary defining the arrow of time. Still, it is appealing to think that time and causality are in an objective way intimately bound up with the transformation of quantum potentials into classical realities, as is the case with this proposal.

Tuesday, May 10, 2005

Fish, Bird and Octopus Consciousness

David Chalmers' blog has a post which links to 2 papers on the subject of fish consciousness. After skimming both, the article by Rose (which is skeptical about fish experience) appears to be based on a flawed premise, which is that experience in humans is generated by the neocortex. While the distinctively human cognitive apparatus resides in the neocortex, experience itself can be traced to older (in evolutionary terms) structures. As pointed out in the other paper by Chandroo and importantly buttressed by the papers in the recent issue of Consciousness and Cognition which I linked to in my recent post, areas such as the thalamocortical system are strongly implicated in experience, which supports the idea that it is shared more widely in the animal kingdom.

Since that last post, I read most of the other articles in the Consciousness and Cognition issue. My favorite was "Identifying hallmarks of consciousness in non-mammalian species", which discussed the avian case as well as the possiblity of some conscious awareness in the octopus! This is an interesting potential case of convergent evolution which wouldn't depend at all on the particular neural structures of vertebrates.

Tuesday, May 03, 2005

How to Get the Many from the One

I am a realist about the existence of individuated natural systems in the world, of which we humans are instances. I also believe that we, as well as all natural systems, are embedded in a larger world-network which shares the same underlying character. So how do I address the ancient problem of how the many could arise from the one?

The classical view of a world comprised of uniform fundamental particles of stuff following simple deterministic laws cannot solve the problem. Large systems in nature gain and lose these particles through time, but retain a nature which seems to transcend them.

If you adopt an event or process ontology, this challenge becomes easier. An event unfolds: it is a becoming. This means a possibility becomes actualized. It then changes the space of possibilities available for the next event. To make this work you do have to violate the purity of monism, but only slightly. The nodes of the network include an ability to actualize and also be actualized. This is a duality, but not a pernicious one. It seems to be the minimum complication necessary to create a chain or network of events. Otherwise there is no change (and therefore really no reality). Whitehead and his intellectual heirs are the most prominent advocates of a view with these ingredients historically.

For a very recent example of how this kind of system can work comes from Gregg Rosenberg. In Chapter 9 and subsequent chapters his book, A Place for Consciousness (which I have discussed previously here and here), he lays out a detailed metaphysical proposal of causality and the structure of what he calls “natural individuals”. To do the work of causation he postulates that there exist two kinds of (interdependent) properties, effective properties and receptive ones. Effective properties have a range of possible values, while receptive properties are needed to place the effective properties and determine them. Then Rosenberg makes one more key move which is to say the receptive property is connective in nature (one receptive field can bind more than one effective property). This allows complexes of effective properties to be bound together at multiple levels of nature (not just the micro-level) to form natural individuals.

The breathtaking ambition of this metaphysical proposal is such that it not only explains causality and the formation of individuals, but the receptive property is seen as that which gives rise to experience for the system, thus forming the basis of a theory of consciousness.

But for now, what I take away from these ideas is that the process of actualizing possibilities can explain the causal structure of nature, and this foundation provides enough richness to create a model which explains the presence of individuated natural systems within the larger world-network.

To finish this post, I want to revisit what I see as the strong compatibility of this metaphysical structure with quantum mechanics. In a measurement of something like an electron, position, charge or spin are the effective properties. The "ability to measure" (or ability to receive information) of the measuring system is the receptive property. The one thing missing from quantum theory is how larger natural systems which have this ability to measure are put together.

But perhaps physicists working on decoherence theory will figure this out. I am intrigued by the work being done here, but am severely limited in my ability to understand the papers (I hope I can find some work by a good philosopher of physics to help me out). Some interesting quotes have stuck in my head from this paper by Wojech H. Zurek (whose work was briefly discussed in this post). After summarizing the progress made in his theory, which among other things involves regarding observers as “open quantum systems, distinguished only by their ability to acquire, store and process information”, he says in his conclusion that “Many conceptual and technical issues (such as what constitutes ‘a system’) are still open.” I speculate that, consistent with Rosenberg’s theory, the “ability to acquire information” also includes a connective property which allows “open quantum systems” to form.