3 Links: Math and Physics

[UPDATE 13 October 2009: Edited for typos and clarity]

First, since I’m on the record as a skeptic regarding the existence of actual or concrete infinities, I’m on the lookout for discussion of this topic. Here’s a talk given by mathematician Edward Nelson (hat tip: Not Even Wrong). In it, he expresses deep skepticism not only (in passing) regarding the idea of an actual physical infinity, but also (very controversially) on the concept as used in mathematics itself. I wouldn’t think skepticism about the former need have anything to do with the latter (and I’m certainly no mathematician), but I thought this was interesting reading.

Second, I enjoyed reading this (lengthy) overview of quantum gravity research by R.P.Woodard. The main focus of the paper is a “pedagogical explanation” of just why the techniques used in creating quantum versions of classical theories didn’t work when it came to general relativity (I thought this was helpful even if one can't follow all the formalisms). There is also a short section on the state of current research. Woodard makes this comment in the section discussing Causal Dynamical Triangulations (p.67): “…exact calculations are unlikely to be unattainable for quantum gravity, so the most fruitful way of questioning perturbation theory [i.e. the QFT method which is also the basis of original string theory – Steve] is to develop better approximation techniques.” The idea of finding a theory of everything (TOE) which consists of a set of equations with exact solutions looks like it is not going to happen. Finding a well-motivated approximate description of the ultra-high energy regime from which GR and QFT matter fields co-emerge at lower energies is probably the way things will go (I fearlessly predict).

Lastly, here’s a link which is just plain cool. Experimental physicists have been trying to place larger and larger molecules in quantum superposition: here’s a proposal for designing an experiment which could achieve this for a virus. Hat tip goes to the Physics and Cake blog.

Power Holism

This makes a nice follow up to my recent reading of C.B. Martin’s book: I found this paper, “Puzzling Powers: The Problem of Fit” by Neil E. Williams. In it, Williams identifies and seeks to address a trouble spot encountered by Martin and other advocates of a powers/dispositions-based ontology. To start, Williams describes three key features of the ontology. First: the powers are intrinsic properties of their bearers. They don’t need external or relational connections for support. Second, the manifestations which they are capable of producing are essential features of the power: those potential manifestations make a power what it is. Third, the actual manifestations occur as a result of reciprocity. Martin in particular stressed the mutual nature of powers working together to produce manifestations, noting different pairings or combinations of powers will lead to different outcomes. Given these three features, Williams sees “a problem of fit.” He says: “Stated briefly, the problem is that powers have to work together when they produce manifestations (reciprocity), but as they are not relations (intrinsicality), and they cannot change with the circumstances (essentialism), the fact that they are causally harmonious is without explanation.” Powers fit together to produce mutual manifestation, but the fact that they fit is not accounted for by the three features they possess. He uses a jigsaw puzzle analogy to suggest that, as it stands, there’s no reason to expect a fit to occur without adding more to the story. So, what to do? Williams doesn’t think it’s advantageous to drop one of the three features he began with. With regard to essentialism, he does mention an alternate idea that the potential manifestations essential to powers are not determinate but are instead “TBD” (to-be-determined) via hooking up with other powers. But he still sees a gap with this idea: what finally makes the particular determinate manifestation finally occur? So, instead, Williams puts forward a solution: “power holism”. The nature of powers is determined holistically: “the specific, determinate nature of each power (that is, the set of manifestations a power is for and the precise partners required for those manifestations) depends on the specific, determinate nature of other powers with which it is arranged in a system of powers.” He notes we also need to discuss the bigger picture of “…what kind of world allows for or provides for the fit that power holism bestows.” How do the powers get their holism on, in other words? He looks at three ways one might address this. First, we could just posit holistic coordination as a brute addition to ontology. But this isn’t very satisfying. Second, he suggests one might look to a platonic account: collaboration between powers takes place in the platonic realm. Third, one might retain naturalism, but suggest a form of monism which could support the coordinated fit. For instance, if all powers ultimately ontologically depended on the prior existence of the whole world (a la Jonathan Schaffer), then this shared basis could explain the harmonious fit. Williams is sympathetic to this option but says any of the choices might be worthy of consideration. A very good paper. I liked the appeal to holism and (although Williams doesn’t use this terminology) non-local connections. In my opinion, though, in order to really nail it down, some indeterminism needs to be added to the model. Fit (correlations) can be explained by the non-local connections, but powers need to be seen as capable of more than one outcome per partner—an irreducible indeterminism only resolved when the manifestation (event) occurs. This would then nicely comport with quantum mechanics. (I see Williams also has a paper co-authored with Andrea Borghini advocating a single-world modal actualism, explained using a powers ontology. I’ll have to check that out – my last post on that topic was here).

First Gunk, now Junk: Infinite Chains of Metaphysical Explanation

I recently read a few philosophy papers which share a common theme. They advocate the idea that there may be no foundational or basic metaphysical level of reality (whether monistic or pluralistic), and that therefore one should (or at least can) embrace infinite chains of metaphysical explanation.

Einar Duenger Bohn, in the draft paper “Must There Be a Top Level?” notes that many philosophers have discussed the conceivability of “gunk”, which is infinitely divisible stuff (a world is gunky if everything in it has, mereologically speaking, proper parts). Bohn thinks that “junk” is also conceivable, where everything is a proper part of something else.

The term junk is drawn from the paper “Monism: The Priority of the Whole” by Jonathan Schaffer (here’s a post which discussed an earlier draft of this paper). Schaffer argued against the conceivability of junk as part of a larger set of arguments in favor of the monistic whole as the foundational entity in a world. (To fill out the glossary, Bohn introduces the adjective “hunky” to describe a world both gunky and junky).

Schaffer says that in discussing possible worlds, a “junky world” makes no sense, since “world” refers to a single entity. Junk has no upward “cut-off” point to contain it within a world. Bohn objects that there is no need to constrain the term world as singular: maybe it can refer to a set or some other plural entity, which allows for junk.

But is junk really conceivable? Bohn offers thought experiments which put junk on a par with gunk with regard to conceivability (imagine each atom in a world is itself a world: now take this idea both upward and downward). What’s wrong with a “hunky” world extending without foundation in both directions?

Schaffer’s paper is also the target of Matteo Morganti’s just published “Ontological Priority, Fundamentality and Monism” (hat tip; no draft available online that I can see). Morganti sees no compelling argument for a foundational level of reality vs. the alternative of “metaphysical infinitism”. He also takes issue with Ross Cameron’s conclusion that we should postulate a fundamental level for methodological reasons if we are to have any satisfying metaphysical explanations (I discussed the relevant Cameron paper in this post).

A third paper, by Francesco Orilia, makes an analogous argument in a different philosophical argument “thread”: he compares whether facts (or states of affairs), which bind an object with its attribute (or relate multiple objects), are basic ontological entities (as in Armstrong), or whether they give rise to an infinite regress of binding relations (Bradley’s regress). Orilia thinks we should accept “fact infinitism” as a live option. (For a very deep dive on this see Bill Vallicella's thoughts and dialogue with Orilia here and here).

So is there a foundational entity or entities or not? Do you really have an explanation when you invoke an infinite chain? There’s a lot to digest here, and I plan on rereading this set of papers and others. My intuition has always been that there must be a fundamental level of reality, but an argument is needed here, not an intuition. I think we can reject gunky/junky worlds. I will go ahead and sketch my speculative argument below (a previous gunk-inspired post with a good comment thread is here).

First, though, let me note that I’m very happy to continue to find members of a new generation of philosophers who are taking up “meaty” metaphysics as a primary focus. Philosophers like Schaffer and Cameron are doing serious and innovative metaphysics, and are provoking responses from other young philosophers (definition of young = anyone younger than me): great stuff.


My tentative position is this (what follows assumes modal realism). When we employ our (remarkable) ability to conceive of infinities we are in danger of making a particular error. As background, I endorse conceivability as a guide to possibility, and specifically think that our concept of what is logically possible maps to what is metaphysically possible. I think this total space of metaphysical possibilities is infinite and this is what grounds our concept of the infinite. Now, philosophers usually refer to this space of possibilities specifically as the space of possible worlds (I think this is rooted in methodological usefulness). However, our attempt to conceive of what is possible in a particular world may be actually importing content which may not fit in one world. We need to be careful about how we define a world.

Consider the actual world. Following David Lewis in one respect (but not in others), I think the best sense of “actual” to use is as an indexical. If I take the actual world to be the causally connected region centered on my point of view, then, based on a posteriori reasons, the actual world should arguably be considered finite: quantum physics as applied to space-time implies no infinite divisibility, and causal connections only extend so far. If all possible worlds are likewise defined as centered causally connected patches, I hypothesize that all “worlds” should be considered likewise finite.

Let me pause here for a moment. Many (most?) thinkers assume that a world is an isolated, bounded spatio-temporal object of arbitrary size. But I assert there actually isn’t a good reason to think there is some clean definition of a world boundary beyond this concept of a causally connected region or patch. (Please note I’m not saying physicists/cosmologists need to adopt my definition of a world or universe, this is just to help make sense of a philosophical problem.) If one asserts a world contains a concrete infinity, then one has exceeded the boundary for what can fit in a world. This is the error.

Now, let’s go back and consider the question of whether there is a foundational “level” of reality using this model of an infinite space of metaphysical possibilities broken down into finite worlds. When considering a world, its “parts” have a good claim for being basic given indivisibility. Since a world can have an irregular and changing boundary as events move into or out of causal contact with the center, the “whole” of the world seems to have less of a claim to be foundational.

On the other hand, let’s consider all of reality, i.e., the total space of metaphysical possibilities (all possible worlds). In this case, there exists an infinite number of ways to parse it, and the parts no longer seem to have as good a grip on being basic. Here it is the total space which is the ultimate source of the reality individual worlds take part in. So in the bigger picture, the monistic whole takes priority, and has the best overall claim to be the foundational entity.

Notes on C.B.Martin’s The Mind in Nature

Philosopher C.B.Martin died last year and left us a great book. The Mind in Nature summarizes his philosophy and its applications to mind, causality and more. For background see Paul Snowdon’s obituary and a brief note on the book by Gualtiero Piccinini; here is a very good draft review by Jessica Wilson. It was not an easy book for me to read but I found it very rewarding. Martin proposes an ontology featuring dispositions (sometimes referred to as powers). Notably for him, dispositions are inherently qualitative, and are also capable of producing myriad manifestations depending on the context.

I have previously read the work of philosophers who feature dispositional properties/powers as a basic element in their ontologies. (Martin has an early section recounting arguments for the irreducibility of dispositions– see the Wilson review for more on this). An attraction of these proposals is their potential to support a theory of real causality and of intentionality – topics mainstream analytic philosophy has trouble with IMO (see my series on George Molnar for more). John Heil adds the twist (along with Martin) that we could consider dispositions to also be qualities, which helps solve an additional aspect of the mind/body problem. Despite these accomplishments I have continued to view disposition-based accounts as falling a bit short when it came to mind and also to modality (see this recent post). Martin’s distinctive account takes another step toward addressing these issues.

Dispositions Offer Possibilities

I think the key to Martin’s ontology is that his dispositions don’t just point to one kind of manifestation, they are prolific. He says that whatever the fundamental elements of nature are, they have multiple internal properties which are dispositions to potentially an infinite number of different manifestations depending on context. Different “reciprocal disposition partners” will give you different manifestations. At any point, what exists is a “…manifestation tip of a disposition iceberg (p.9)”.

One doesn’t need “possible worlds”, since dispositions and their “projectivity” of actual and non-actual manifestations with various partners constitute a web or “power-net (p.29)”. In fact actual readinesses exist for infinite potential (Wilson points out this assertion is not backed up by an argument), so you don’t need any further grounding for possibility. (Upon reading this my own thought was why couldn’t Martin just redefine possible worlds as possible power-nets?). I note Martin himself isn’t vehement in asserting he’s definitely provided a full and adequate grounding for modality, compared to his tone when defending other aspects of his view.

Emergence/Reduction

For Martin, the creative power of dispositions means you don’t need “levels of reality” or the notion of supervenience. He sees all reality as a continuum “going from the many directional readiness of the quark, most of which will never be manifested, to the capacities and dispositions for many representations of some English speaker, most of which also will never be manifested (p.29)”. (Note that in contrast to the mainstream of analytic philosophy, language is not primary: the ontology comes first). The basic ontology is rich enough that emergence occurs through processes at the one level of reality; emergence is not a concept implying or requiring multiple levels.

Causality and Events

The manifestation of a disposition is the basis unit of causality. At one point (Ch.5), Martin stresses that causality in his view is not a temporally separated thing. The reciprocal partnering of dispositions creates a mutual manifestation; the model is of a “cause-effect” rather than cause-then-effect. (I would say, in other words, an event.) Martin doesn’t much address the problem of time and its perceived unidirectional flow. He takes the space-time of Einstein to be a substratum carrying the dispositional properties.

Mind

With regard to mind, Martin stresses that dispositions (which are inherently directional) give you intentionality at level below what we think of as “mental”. He also gives an account of how a natural system utilizing representation comes into being; he is inspired by results in neurobiology which he takes to show that “vegetative” (i.e. unconscious) systems of the brain effectively utilize representations already. So intentionality and representation are not distinctive hallmarks of human consciousness.

And neither are qualities. Martin first says dispositions cannot be identified with structural properties (such a view leads to an empty “Pythagoreanism” in his view). Even structureless elementary units (quarks or whatever) have multiple internal dispositions. And there is no need for purely qualitative, non-dispositional (categorical) properties. It is dispositions through-and-through and these dispositions are themselves simultaneously qualities (Wilson’s review also discusses criticism of this dual-aspect idea citing Armstrong).

So what does distinguish the mental? Here Martin offers a model which says the difference between mental and non-mental lies in the kind of qualitative material used in a representation. If the material of use is appropriately sensory, we get consciousness. I’m giving this model short-shrift here a bit in my notes (chs.13 -15), but I was a bit disappointed by it. Given Martin’s emphasis on gradualism, i.e. having nature exploit its base level qualities to give rise to all phenomena, I found his account of mind to be ad hoc. Since we’re making some brute assumptions in our ontology anyway, I would prefer to just couple the experiential aspect of reality to the qualitative aspect at the base level as two views of the same thing (possessed by each mutual manifestation). Then the emergence of human consciousness would be likewise gradual and not wholly dependent on functional criteria. (Wilson has a somewhat similar critique in the last part of her review).

Propensities and Quantum Physics

I was happy to see Martin tries to grapple (briefly) with quantum physics (in his chapter 6). In a section called “Dispositions and Quantum Theory”, Martin briefly discusses quantum theory and the interpretational question of assigning ontological status to the wave function vs. the measurement events. He thinks a system as described by the wave function could be taken as a propensity, which is a bit different idea than a disposition which points to specific manifestation. There seems to be a metaphysical gap here (correlating to the problem of the “collapse of the wave function”). He suggests that a “dispositional flutter” or oscillation might cause the appearance of irreducible probability. He says the flutter could be a consequence of practical limits on detection, or an intrinsic random oscillation. Unfortunately, I think we know this kind of interpretation of QM doesn’t hold up.

I thought it would have been consistent with his views if he identified his dispositions as wave function-type propensities and than had his “mutual manifestation” event map to the quantum measurement event. There still is an element of apparent mystery or gap surrounding the triggering of events, but I think we have to accept that this is just a given feature of the world, given QM.

Stenger vs. Quantum Gods, Part Two

As I mentioned at the outset of the last post, Victor Stenger’s second goal in his book Quantum Gods is to critically examine “quantum theology”. This refers to attempts to rework traditional notions of God’s role as creator and/or intervening agent given modern physics. My review of this part of the book is below.

The Demise of Classical Deism

Trying to accommodate belief in God with a scientific worldview is not a new endeavor of course, and Stenger includes a discussion of “enlightenment deism” in the book. Newtonian physics provided a good foundation for the view that God created and planned the universe, but doesn’t further intervene (the clockwork universe). The theory of natural selection strengthened the case for deism vs. theism by weakening the perceived need for special divine action in the biological world. Quantum mechanics, however, made enlightenment deism untenable by introducing irreducible indeterminism; it appears God could not have ensured his planned outcomes in an essentially chancy world.

What About Emergence?

Stenger has a good discussion of the topics of complexity, chaos and emergent phenomena. Some have argued that emergence introduces “something more” into the makeup of the world beyond the basic physical entities. Some theologians think emergence may leave an opening for God to act in the world. Reviewing a few examples of emergent behavior (e.g. thermodynamics and fluid mechanics), Stenger argues all are cases of what he labels “material reductive” emergence. His main point is this: he says the fact that macro-principles cannot be deduced from microphysics is true and notable, but they nevertheless follow from, and thus are implicit in, the microphysics. The demonstration of this comes with the increasing power of computers to simulate emergent phenomena from the micro-facts: nothing “extra” is needed to do this. There is not a reasonable basis for “top-down” causality between levels of nature based on the phenomenon of emergence. Thus no opening is left here for theology to improvise a story about divine action.

I have found this topic to be difficult in the past, but I think Stenger’s position is well defended. My opinion is that the only really persuasive instance of ontological emergence is the crystallization of actual outcomes from the set of possibilities represented in a quantum state. (But while I don’t see a good case for further levels of ontological emergence or top-down causality once we’re dealing with larger (decohered) macroscopic systems, it is still highly suggestive that so many remarkable phenomena manage to be implicit in the micro-realm.)

Special Divine Action via QM?

In his Chapter 14 (“Where Can God Act”), Stenger reviews attempts to locate divine action in the world of modern physics. He briefly summarizes a number of articles from a Vatican/Center for Theology and the Natural Sciences (CTNS) multi-volume book series which address this and related issues.

Some authors think quantum indeterminism allows scope for subtle interventions, which, when combined with chaotic amplification, might lead to undetectable yet significant effects. Stenger first notes a common observation about such interventions: it seems that this kind of action is “God acting against God,” since the advocates of this idea also view God as the creator of the universe and its physical laws. Also, given the attribute of omnipotence, why should God restrict himself in this way? And it’s not clear this would work anyway. Stenger points out the time lag involved with chaotic amplification: given continued micro-chanciness, how can God be sure he’ll get the macroscopic effect he wants? If he acts to guarantee the outcome, then we’re back to wondering why he doesn’t just use his power to orchestrate all micro-processes to being with? Then, of course, we wouldn’t have indeterminism after all. (And this causes the additional problem of undermining the case for indeterminism-based free will, which is also advocated by some theologians).

I’m obviously oversimplifying the discussion in this summary, but I’ve read a number of these accounts over the years (many from my subscription to CTNS’ Theology and Science) and I agree with Stenger that attempts to implement special divine action with modern scientific tools seem fraught with difficulties.

Quantum Deism

In Chapter 15 (“The God Who Plays Dice”), Stenger notes that the problems with models of divine action do not rule out the possibility of a deist creator God. Perhaps God endowed the universe with indeterministic law as part of this creative plan. Of course, then, there was no guarantee humans would arise – so we couldn’t have been a part of a special plan, could we?

Stephen Jay Gould used to argue that evolution lacks any necessary directedness toward complexity or sophistication: if we “replayed the tape”, we might get a completely different outcome with no guarantees of intelligent life. Stenger notes that Simon Conway Morris is a recent advocate of a contrary view, however. Conway Morris argues, based on observed cases of convergent evolution, that humankind (or something very close) was inevitable. Is he right?

Stenger quotes Elliott Sober’s critique of Conway Morris, which centers on the fact that one can’t show the probability of evolutionary events: we only know the numerator, not the denominator (we unfortunately cannot run additional trials). Stenger adds that since out of the millions of species on earth, most are microbial, “intelligence would not seem to be very high at all on the universe’s agenda.”

Still, we could have a deist God if we accept that God created a cosmos with lots of chancy potential, and was willing to let the chips fall where they may. Such a God, of course, isn’t very attractive to those who yearn for a more traditional deity.

Is there an adequate basis for believing in the existence of (at least) this new kind of deistic God? Stenger doesn’t think so. He spends his last chapter (“Nothingism”) exploring his favorite ideas for a naturalistic account of the universe’s origin. I’m going to skip over these speculative ideas in this review. I think in the coming years work in cosmology and quantum gravity research will be offering new scenarios for how the observable universe arose from a pre-existing context (see for instance here). The point for Stenger is that if a naturalistic account of the universe’s origin is available, then we don’t need a deist God either. And he would answer the question: “who created the laws” by responding that laws are human inventions to describe regularities we observe. This is also a very defensible position.

What about the Multiverse?

Stenger doesn’t devote significant space to the idea of the multiverse apart from his brief section on the Many-Worlds Interpretation. But in addition to interpretations of QM, an increasing number of physical and cosmological theories motivate the possibility of a multiverse. There are also independent philosophical reasons for postulating that our universe is a subset of a larger reality.

I agree with most of Stenger’s criticisms of the various conceptions of God. However, the multiverse is the one conceptual place where I see the potential for a naturalistic worldview to make contact with a notion of God (albeit one which is non-traditional and impersonal): a transcendent and creative entity of which we are but a small part.

Stenger vs. Quantum Gods, Part One

I read Quantum Gods: Creation, Chaos, and the Search for Cosmic Consciousness, by Victor Stenger. Stenger is a physicist who is in the popular-book writing business with a focus on the science vs. religion debate. I found the book to be thought-provoking and worth reading, although I have a couple of substantial criticisms.

The motivation behind the book is a good one. Stenger’s most recent prior book (he has written quite a few) was God: The Failed Hypothesis -- an entry in the recent mini-boom of books by materialist-atheists criticizing traditional Judeo-Christian-Islamic religion. (I didn’t read this book having read Dawkins, Dennett and Harris in the genre). Quantum Gods is intended as a sequel which moves beyond traditional religion to criticize some newer and less traditional ideas about God and spirituality.

Stenger spends the first chapter looking at surveys on belief (including this Pew study), and notes they at least suggest that a substantial number of self-identified Christians have non-traditional ideas about God (in particular indicating beliefs more reminiscent of deism than theism). Also, he suspects that a significant portion of “unaffiliated” respondents have replaced traditional religion with various spiritual and/or paranormal beliefs (someone is buying lots of books by new age-type authors with these themes.)

With this as backdrop, Stenger explains that one strand which ties together some newer theistic/deistic ideas as well as the new age spiritual ones is their efforts to incorporate or accommodate modern physics (hence “quantum gods”). He identifies, then, two targets: the first, which he labels “quantum spirituality”, is the group of new age-type ideas which invoke quantum physics to support ideas about personal spiritual powers and/or cosmic consciousness; the second target, called “quantum theology”, is a set of attempts to accommodate God’s putative role as creator or intervening agent with modern science.

Before proceeding with more detail I need to mention one annoyance I had with the book: it felt somewhat padded to get to book-length. At 263 pages, about half (roughly the middle half) consists of encyclopedia entry-style sections on topics in the history of science. The content is unobjectionable, but this wouldn’t be the book you’d choose to read to learn about classical physics, relativity, or the history of quantum mechanics (QM) and the standard model of particle physics.

I thought the best part of the book were the late chapters criticizing “quantum theology” – i.e. some modern theological ideas about accommodating religion and science. I just wish he had a lengthier survey of these. A common objection to the work of the “new atheists” is to say that they haven’t grappled with more sophisticated modern theology but only criticize traditional beliefs (which are, of course, those held by the large majority of laypeople). Stenger has a good first effort to fill this gap, I thought. I will say a bit more about this section in a follow-up post. Below I will address Stenger’s criticism of new-agers and “quantum spirituality”, which I didn’t think was as effective.

Mind over Matter?

Let me quickly say that one of the reasons the chapters criticizing “quantum spirituality” aren’t as satisfying is not Stenger’s fault. Some of the ideas in books like those of Deepak Chopra and Gary Zukav, and movies like “What the Bleep Do We Know” just aren’t serious. Inspired by an apparent link between observation and the outcome of quantum measurements, a major claim of these folks is that quantum physics shows that human beings “create their own reality”: thus one can heal illnesses and become wealthy (or perhaps do some yogic flying) through the power of one’s mind. I personally think the details of QM could be implicated in the eventual scientific explanations of life, mind and freedom. However, to the extent that extrapolations from QM are used to portray humans as capable of paranormal powers, we cross into crackpot territory, and there’s not a lot more one can say (Stenger provides a section in Ch. 12 reviewing paranormal claims).

My main problem with Stenger’s discussion, though, is that his own opinion about the interpretation of quantum mechanics is highly idiosyncratic: he tries to hew as close as humanly possible to the worldview of classical materialism. As keen as he is to refute the quackery, he is as just as critical of the idea that the interpretation of QM might have any relevance to explaining the relation of mind to nature. He also is dismissive of the common notion that the ontology of QM or quantum field theory is suggestive of a more holistic cosmos than classical materialism. Here he is on less firm ground, in my opinion.

Saying No to Holism

With regard to holism, Stenger devotes a couple of sections discussing Fritjof Capra, one of the progenitors of the quantum new-age publishing genre with his book, The Tao of Physics (1975). In the book Capra stressed connections between QM and eastern philosophies, which he said both emphasize interconnectedness and process. Stenger points out that Capra was inspired by his work on a research program which was proposed as an alternative to quantum field theory called S-matrix/bootstrap theory. He points out that this program didn’t pan out, and this undercuts Capra. Stenger also has a brief discussion of quantum luminary David Bohm, who late in his career also espoused a holistic philosophy inspired by his work on the interpretation of QM (for instance in his book The Undivided Universe, written with Basil Hiley). Stenger notes the fact that Bohm’s “hidden variable” view is not widely embraced, and implies this undermines Bohm's philosophy.

It seems to me that most interpretations of QM and QFT, not just Capra's and Bohm's, can reasonably be taken to imply a more non-locally connected and hence holistic view of reality compared to the classical picture (what, if any, implications this has for the world beyond particle physics is a separate discussion). Prior to measurement, "particles" are spread out in space-time and systems demonstrate entanglement. The wave aspect of reality has a holistic element. However, it turns out Stenger doesn’t want to concede even something this modest.

Forget About Waves!

We learn more about Stenger’s own views in Chapters 12 and 13, where he discusses the interpretation of QM. He gives some brief sketches of Copenhagen, hidden-variables, and many-worlds interpretations. His own view, surprisingly, begins with a claim that there is no wave-particle duality; there are only particles. He has a section entitled “The Fictional Wave Function”. He says the description of the quantum state is an abstract mathematical entity. He spends a paragraph downplaying the Schrödinger representation of QM, preferring Heisenberg’s and Dirac’s formulations, which lack the wave function (he does remind the reader that they all give equivalent results).

So, if only particles exist, and no ontological status is given to the quantum state, how do we interpret experimental results? Discussing a single-electron double-slit experiment, Stenger’s idea, inspired by Feynman’s diagrams, is that the single particle, traveling backward and forward in time, can produce the interference pattern. I ask: how can it do this with no guidance from a wave? (Also interesting to me is that Stenger throughout the book is quick to dismiss anything that might imply violation of special relativity, but he’s OK with time-reversal). That’s the end of the discussion, so I can only infer that Stenger thinks QM can be successfully interpreted as a particle-only ontology with time-reversal. I’d never heard this view before and it isn’t defended at any length (it may be given more discussion in a previous book).

Can QM Explain Consciousness?

What about mind? Stenger does mention in passing that Von Neumann and Wigner suspected mind was involved in the phenomenon of quantum measurement. Beyond that he mentions the Penrose/Hameroff proposal for microtubule-based quantum coherence in the brain. He dismisses this with the standard reference to Max Tegmark’s 1999 paper calculating decoherence scales. I personally think Hameroff’s speculations are unlikely to be true, but recently it has been established that quantum coherence can be maintained and exploited by biological systems (see also here). While it still seems unlikely that anything as large as neuronal assemblies can maintain coherence, the science of tracing the role of quantum effects throughout biology is only getting started. I think it is quite plausible that distinctive features of life and mind may yet have at least a partial (non-trivial) quantum-mechanically-based explanation.

So, my main question for Stenger is this: why throw out the baby with the bathwater? We don’t live in a classical world, and we should continue to probe the implications of living in a quantum world wherever it takes us. Let’s not let the fact that New-age folks are making unsupported claims close our minds to the possibilities.

An Improved Supervenience Base?

Brian Weatherson (home page, blog) has authored an SEP article on David Lewis. In it he ably takes on the difficult task of summarizing in a few dozen pages the work of one of the most prominent and productive philosophers of the latter part of the twentieth century.

One section addressed something I had idly wondered about Lewis. As Weatherson discusses in his section 5, entitled “Humean Supervenience”, much of Lewis work involved reduction: whether the subject was the mind, language, laws of nature, or causation (modality was a rather spectacular exception), he presented arguments that all the truths about a world ultimately supervene on a set of (perfectly natural) properties and relations in that world. He then argued that these, in turn, are intrinsic properties of point-sized objects and spatiotemporal relations. (The “Humean” aspect of this is that he follows the spirit of Hume’s “dictum” that there are no necessary relations between distinct entities.)

What I had wondered was: did Lewis ever acknowledge that his picture of locally distributed point-sized objects in a space-time container was a classical view, inconsistent with modern physics?

Those who challenged this aspect of Lewis’ work over the years argued that his supervenience base is incapable of supporting some of the truths about the world, and so his attempts at reduction fail. However, most critics haven’t quibbled with the assumptions about physics, rather they argue that some additional higher-level properties and/or relations need to be added to explain the world. Even many materialist philosophers think additional brute metaphysical structure beyond the basic physical entities is required (this debate was the subject of this old post); some philosophers think necessary connections are needed to explain causation; dualists will see a need for fundamental mental properties and perhaps psycho-physical laws.

But, Weatherson notes that a second way to argue against Lewis’ project is indeed to point out that modern physics is inconsistent with Lewis’ notions. At a minimum, he says, quantum physics seems to need non-spatiotemporal relations to explain Bell’s theorem.

Weatherson explains that Lewis was indeed aware that his picture was inconsistent with quantum physics, but still thought it was extremely valuable to defend the thesis regardless of that fact. Weatherson explains the idea as follows: to the extent his picture of physics is wrong, it is because physics has more content in it (e.g. entanglement relations) rather than less. So, if Lewis can successfully defend reduction of various folk theories on his terms, it will remain a valuable accomplishment.

That makes sense, but I still wonder if explicitly reckoning with quantum physics and its interpretation couldn’t helpfully reframe these philosophical debates. There is more to the shift from classical physics to quantum physics than just adding some non-local connections. There is the quantum measurement event itself, which I see as an ineliminable new addition to the basic constituents of nature. I think that mind and causation might be the targets of successful reduction given an improved supervenience base which featured a network of measurement events in its basic ontology. (Also, one neat thing about taking this approach is that we could hold on to Hume’s dictum. He may not have known about QM, but I think the indeterminism involved in measurement events is consistent with his insight.)

Kriegel on Animal Rights, Part Two

(Note: part one of this post is here)

In section 5 of his paper, Uriah Kriegel outlines a proposal for a different, non-consequentialist, ethical framework for animal rights. He starts by saying he admires the part of Kantian (deontological) moral philosophy known as the “humanity formula”: one should treat another’s humanity (or one’s own) as an end in itself, not as a means to an end. To extend this approach, he suggests substituting “conscious creatures” for “humanity”.

With some alterations (including what he calls a “virtue-ethical” twist), the formula becomes:

“One should have the stable, dominating disposition to treat conscious creatures as ends in themselves and not merely as means to other ends.”

The “stable, dominating disposition” phraseology allows us to avoid absolutism in the formula. Including “merely” allows for cases where an animal might be treated in some fashion as a means as well as an end in itself. Kriegel notes that much more could be said about all of the nuances here, but he moves on to give examples of how this kind of formula would result in different results compared to a consequentialist formula. Importantly, they differ on whether it is right to kill or exploit an animal if could be done painlessly. By assigning conscious animals intrinsic moral worth, one expands the animal rights case (for those animals considered conscious).

I liked this proposal very much, since I have long been attracted to the idea of assigning intrinsic moral status on the basis of consciousness (although I came to the idea from a different direction – see an old post on this here and other posts with the Morals tag). And while I certainly don’t read a lot of philosophical papers on this topic, I hadn’t seen this proposed before in the literature.

In the last section of the paper, Kriegel returns to the risk that we err in our empirical assessment of the presence of consciousness in various animals. Here he proposes that, given the uncertainty involved, we should assign probabilities to the presence of consciousness. Further we should use a function which maps this probability to an even more generous probability that a given animal should be afforded rights. While all of the numbers we might assign are going to be imprecise, by being cautious about what we know and building in a cushion in our formulas, we can reduce mistakes while pressing the circle of moral generosity outward.

My own view is that in our judgments we should explicitly consider that consciousness comes in degrees, rather than being an all-or-nothing phenomenon. But working with Kriegel’s probabilistic formulas, one could easily get to the same answers in most cases.

Kriegel’s “Animal Rights and Conscious Experience”

(Note: this is half of what will be a two-part post. UPDATE 20 July 2009: the second part is here)

Uriah Kriegel, assistant professor of philosophy at the University of Arizona, has posted this draft paper which seeks to advance the discussion on animal rights in light of progress in the study of consciousness. The most important part of the paper, in my view, is his formulation of how to explicitly make the (likely) presence of conscious experience the key component of a framework for assigning moral status to animals.

Before getting to his own proposal, Kriegel considers how the most influential consequentialist approach to animal rights (prominently associated with Peter Singer) suffers from a lack of an up-to-date analysis of the science of consciousness. This consequentialist framework, which emphasizes maximizing pleasure and minimizing pain, typically doesn’t incorporate a sophisticated understanding of exactly which animals might have conscious experience of pleasure and pain, as opposed to an unconscious functional analogue of these feelings. The former are presumably the intended recipient of moral consideration, not the latter.

Kriegel uses his own work on (human) consciousness to show how the view of animal rights would be influenced by a more detailed account of consciousness. Kriegel starts with his own proposal for locating the neural correlate of consciousness (NCC) in humans. This proposal, which he calls the cross-order integration hypothesis (COI), is detailed in a paper published in the journal Consciousness and Cognition. Then he argues that a comparison of brain structures between animals and humans should inform a view of whether animals share the NCC, and hence are conscious.

Without getting into all the details here, Kriegel’s COI theory implicates activity in cortical structures, presumed to be involved in higher order monitoring work, as a necessary part of the NCC. Because our mammal cousins share these structures while non-mammals lack it, this would provide evidence that the former are conscious, but the latter are not. In considering the consequentialist approach to animal rights sketched above this analysis would serve to help define the circle of moral consideration: in this case, mammals are on the inside, other animals are on the outside (“looking in”).

While Kriegel has some confidence in his approach, he clearly notes in the paper that his moral stance will be tempered by the uncertainty around the empirical conclusions underlying such a moral calculus (his preference is to couch any moral formulas incorporating the empirical claims in terms of probability). And I should stress that the general point on methodology has value even if one’s theory of the NCC differs: just plug in your own preferred NCC and try to judge how far it extends into the animal kingdom. For myself, while I like Kriegels’s “top-down” approach to the question of locating the NCC (i.e. beginning with a theory before you look at the experimental data – see an old post on Kriegel’s philosophy of mind here), I don’t have a high level of confidence in his (or any other) specific NCC proposal yet. The field is still in its early stages.

Still, even if one gains confidence in identifying the NCC in humans, there is a very big step to cross when considering the consciousness of animals, which Kriegel may underestimate. Because brains and bodies have demonstrated a robust ability to adaptively implement analogous functions using distinct structures, I would be very cautious in assuming that the work performed by our late (evolutionary) vintage neural structures couldn’t be implemented differently in animals. Even cephalopods, whose nervous systems have little in common with ours, show behaviors very suggestive of consciousness. Reinforcing this concern is my own philosophical bias to see consciousness as something which comes in degrees. An animal without a cortex could have an attenuated version of consciousness, as opposed to a lack of consciousness.

After the lengthy discussion of the how his kind of empirical analysis can help in evaluating the consequentialist ethical approach, Kriegel shifts gears and discusses a different non-consequentialist framework for the problem.

(To be continued.)

Contemplating the Deeply Strange

I watched this bloggingheads.tv dialogue between Robert Wright, whose latest book (The Evolution of God) I reviewed in the prior post, and Tyler Cowen, economics professor and prolific blogger at Marginal Revolution. They discussed Wright’s book but also expanded somewhat on each of their own views. One thing both men have in common is that they are non-believers, but take the challenge of responding to religious impulses seriously. I wanted to highlight here a good point made by Cowen. (The relevant parts of the dialogue span a couple of minutes beginning at 38 minutes in, then a few more starting at the 47 minute mark.)

Paraphrasing, Cowen says most non-believers should think more about religion and should specifically take the design/fine-tuning argument seriously: contemplation of this often leads to the concept of a complicated multiverse. He says we need to consider that our common-sense view of the world is wrong, and that there is room for a “deep strangeness” in reality. He mentions quantum mechanics and says one has to come to terms with a reality that seems absurd. He says his alternative to believing in God turns out to be believing something strange as well.

I would add that the multiverse concept in particular, is not only strange, but, if embraced, commits one to acknowledge something transcendent (a reality far beyond our observable universe). Investigations of our world have led to several ways to motivate the multiverse: in addition to the fine-tuning argument and the interpretation of QM, there are extensions of specific cosmological theories (eternal inflation, the string theory “landscape”), and there is the modal realism of philosophers. If a non-believer is motivated to explore deeper explanations of reality, he or she will almost surely end up somewhere well beyond a common-sense starting point.

Once you rule out the supernatural entities and interventions of traditional theism, there’s still a lot of hard work to do to explain what’s given to us: and the journey may lead to places one didn’t intend to go.