Montero on Russellian Physicalism

There is a lot of interesting material at the Consciousness Online conference currently underway. One paper I enjoyed reading was Barbara Montero’s entry on the Russellian theory of mind: “Russellian Physicalism”. In addition to Montero’s paper and powerpoint slides, there are links to responses by Emmett Holman and Daniel Stoljar, who have both also written on this topic in the past (see my old posts here and here).

Montero reminds us that the Russellian approach is a non-dualistic strategy for dissolving the conceivability argument against physicalism/materialism (most famously depicted as the “zombie” argument). David Chalmers' most recent paper updating the conceivability argument had as its conclusion: “materialism is false or Russellian monism is true.”

Russellian monism argues (roughly) that our knowledge of the physical world is only of its extrinsic or dispositional (causal) aspects. Physical entities also have intrinsic or categorical aspects. These hidden aspects are those responsible for consciousness. When we try to conceive of zombies, we fail because we are not conceiving of all relevant aspects of the physical world.

Montero’s paper focuses on the fact that while Russellian monism can be interpreted as a form of panpsychism (the intrinsic aspects are in some fashion mental or experiential in nature), it can also be cast as a variety of physicalism (where the intrinsic aspects are not to be seen as themselves mental).

I'll note parenthetically that both versions face further challenges. In the case of the physicalist version, it can be argued that the explanatory gap between the mental and the physical still isn’t bridged (even though the formal conceivability argument is defeated). In the panpsychist version, we arguably address the gap, but we are left with the “combination” problem: how do micro-phenomenal entities or properties combine to form macroscopic minds like ours?

The responses by Stoljar and Holman and further discussion in the comments mostly revolve around thorny issues of terminology. What do we mean by “physical”, “mental” etc. as it relates to these hidden intrinsic aspects of nature? I tend to like the approach Stoljar took in his book (finally out in paperback), where he threw out these terms and used experiential and non-experiential. Holman proposes using “subjective unity” as the key feature to distinguish things.

I enjoyed the discussion (which continues in the comments), and I hope that philosophers of mind continue to focus on this topic.

Postscript: I have a general quibble, which is that I think this all becomes clearer if you go back and read Bertrand Russell himself (Montero, taking Chalmers as her starting point, includes just one short quote from Russell). Russell’s approach, beginning in his Analysis of Matter, is distinctive for his careful critique of physical theorizing and for his use of a causal event ontology. Russell reminds us that physical theory consists of describing a causal structure connecting the experiential events which occur when we conduct empirical research. The physicists create mathematical models to allow them to generalize and extrapolate to describe events beyond our direct experience. He then argues that it is a philosophical mistake to ascribe reality to the mathematical models themselves (what Whitehead called the “fallacy of misplaced concreteness”). The causally connected events are the reality. We have no good reason to think the “physical” events which we infer have a different character from the events we experience directly. At a minimum we can be confident that an event is ontologically more than just a point in a mathematical model. Whether we think all events are experiential (leading to panpsychism) or not is something for further debate. Russell himself took the conservative option here, and was reluctant to posit panpsychism, while his former collaborator Whitehead went ahead and took the panpsychist step in formulating his process metaphysics (see also my post on Carey Carlson’s book on Russell and Whitehead).

I Heart Philpapers

David Chalmers announced here the creation of the philpapers.org site to aggregate and provide tools to explore philosophical works of all stripes. It looks stupendous. David Bourget has spearheaded this effort with Chalmers.

So, I was curious whether the site had any online papers or drafts by philosophers of science on the topic of emergent-spacetime approaches to quantum gravity research (I had not yet seen any to date). Voila, I found this nice paper by Jonathan Bain on the condensed-matter physics-based approaches.

There is no way someone outside a university setting like me could keep up with the work of philosophers without the internet. So, while I know I'm not the intended beneficiary of all this effort, I’m nonetheless extremely grateful to the individuals who have worked over the years to aggregate the online papers: including (in addition to Chalmers and Bourget) Brian Weatherson, Jonathan Ichikawa, and Wolfgang Schwarz.

Anathem Metaphysics

(“Metatheorics”, I should say)

Most Neal Stephenson fans probably read his book Anathem last fall, but I just finished. There are many reviews available, so I won’t add one here, but I got a big charge out of some of the philosophical ideas Stephenson put in the book.

In the course of the novel, Stephenson proposes an interesting relationship between platonic truths, the multiverse, and human rationality/consciousness, which I have enjoyed comparing to my own ideas (discussion below the fold).

The main idea is that the platonic realm is not a single transcendent world out there, but rather the source of platonic ideas is to be found in the multiverse (called the “polycosm” in the book; the overall theory is called “complex protism” where protism=Platonism and “simple protism” would be the positing of a single platonic realm).

The core of this idea is one I endorse here in the non-fictional realm, and it was very cool to see it in the novel. Modal judgments about what is possible and what is necessary play a crucial role in our reasoning. At the same time, both philosophers and theoretical physicists have proposed that our world is one member of a set of many possible worlds. If we propose that the logical possibilities we explore with our minds are identical with real possibilities present in the multiverse, then the multiverse can be seen as the source of our rationality, and of our knowledge of abstract truths. (The philosophical term for the match-up between logically possible worlds and metaphysically possible worlds is modal rationalism).

But how does a human mind access the multiverse? First, let me note that the type of multiverse being proposed in the book is inspired by the many-worlds interpretation (MWI) of quantum mechanics (QM). So the solution is to have the mind exploit the quantum realm. There’s a dialogue between the characters Orolo and Erasmus (pp. 543-548) where they discuss how the presence of the same person’s brain in multiple adjoining and interfering worlds gives the brain access to possibilities. Stephenson’s characters later make the point (which I liked) that it isn’t that the human brain is the only thing which is in contact with possibilities; one should assume everything in the world experiences some contact, but it is in our own brains that we can best see the evidence manifested (pp. 690-92).

I’ve come at this in similar spirit, with one apparent difference when it comes to interpreting QM. I believe that our world is comprised of quantum measurement “collapse” events, which each embody the actualization of one of many possibilities. The fact that we humans are ultimately grounded in quantum-level events gives us a kind of direct acquaintance with possibilia in everything we do. That makes our ability to have modal knowledge intelligible, even though we don’t yet know the manner in which our brain/body system leverages this presumably micro-level contact into macro-level knowledge.

It appears Stephenson’s idea is to try to preserve the MWI (which attempts to do away with measurement events), while allowing contact between parallel worlds to be exploited by the mind. MWI would not typically be seen as allowing any contact. Also, usually in MWI, worlds branch (what we think of as a measurement is a splitting of worlds), whereas Stephenson wants to keep worlds in parallel. Of course, positing contacts between parallel worlds is very helpful for the creating the exciting parts of the novel which involve characters and spaceships moving between worlds.

The other aspect of Stephenson’s multiverse which is interesting is that the informational contact between worlds has a flow, where some worlds are upstream or downstream from one’s own world. It seems he places a single purely platonic world at the source of the information flow (whereas I would follow the usual philosophical tradition of identifying logical and mathmatically necessary truths to be those things true in all worlds). I’m not sure this makes sense or was philosophically motivated, but it was a neat twist.

There are allusions to many other philosophical and scientific ideas in the book, and Stephenson discusses many of the sources which inspired these in this acknowledgments page on his website. There’s more to follow up on there – one philosopher he discusses who I have not read is Edward N. Zalta.

[I have a number of old posts on related topics, including
Making Abstract Truths Intelligible
Modal Realism, Modal Rationalism
Multiverses -- Physical and Metaphysical]

More on the Fundamental Status of Time

Here are two more links to arguments for why time is fundamental:

A very good talk by Lee Smolin at a Perimeter Institute conference last fall. I thought he did a very good job in explaining how physics got into the practice of viewing time in a geometric fashion (with no important role for the present moment) and why this will not work when formulating a theory of the universe as a whole.

Here's George Ellis in another entry from the FQXi essay contest explaining why it is a mistake to try to describe the universe without time asymmetry.

Review of Quantum Aspects of Life

Quantum Aspects of Life is a collection of papers edited by Derek Abbott, Paul Davies, and Arun K. Pati which was recently published by the Imperial College Press (this review refers to the paperback edition). The target topic of the book is the role played by quantum mechanics (QM) in living things. Actually, we need to be more specific than that, since it’s accepted that all biology is based on chemistry, and chemistry is inherently based on quantum physics. In the book, the key distinction is described in a couple of different ways: in the foreword, Sir Roger Penrose distinguishes between “strongly” and “weakly” quantum mechanical features utilized by living things; the editors’ preface says the intent is to address the question of “whether quantum mechanics plays a non-trivial role in biology” (p.xiii). In each case the phenomena in question are those which are distinctively quantum mechanical: superposition, entanglement, tunneling, etc.

The volume is very welcome, since the topic seems to demand more focus than it has received. Confirming a significant quantum role could have a huge impact – both on the practical pursuit of biology and the philosophical perspective we take on the nature of life and mind.

There has long been a good circumstantial case to be made that the remarkable nature of non-trivial QM effects may serve to help explain the remarkable capabilities of biological systems. The foreword, preface, and Davies’ opening chapter all invoke Schrödinger’s 1944 book What is Life? as the ur-text exploring this idea. However, experimental confirmation of QM’s role in life didn’t follow, and molecular biology experienced huge growth and success nonetheless. Again repeating themselves a bit, the editors, Penrose and Davies each lament that the science of the intervening decades has been dominated by the “ball-and-stick” model of chemistry. They seem to be implying that scientists (for institutional reasons perhaps) haven’t been bothering to look for quantum effects. Of course, a hurdle for the idea, not as explicitly evident in Schrödinger’s time, is the phenomena of environmental decoherence. An issue running through the book is the challenge posed by the fact that maintaining quantum coherence is very difficult even in carefully controlled experimental settings.

While experimental confirmation of non-trivial QM effects in biology has indeed been elusive, it has not been absent, and a recent result strikes me as not only important, but possibly seminal. I’m referring to the 2007 Engel, et.al. paper in Nature which showed the utilization of quantum coherence in photosynthesis (please see the post “Quantum Biology Goes Mainstream” for links). The timing of this result’s publication was such that it either barely pre-dated or else post-dated the submission of papers to Quantum Aspects of Life. As I read the book, I was often thinking about how this result might change the debate as we move forward: it not only showed the utilization of QM in one of the core processes in biology, it also showed the engineering challenge (and attendant resource demands) which are involved in confirming the presence of such a phenomenon. There are quite a number of papers out there which present theoretical models which postulate QM effects to answer outstanding questions in biology -- here’s a good example of this sort of paper I saw recently – but confirming a theoretical result is another story.

Quantum Aspects of Life begins with a nice foreword by Penrose, whose perspective will be familiar to those who have read his books. He thinks the human mind will demand a quantum-derived explanatory account (which he thinks will be linked to a future theory of quantum gravity). Now, environmental decoherence becomes an increasingly strong obstacle as distances lengthen, so quantum computing in the human brain seems unlikely to be a result of quantum coherence extending across neuronal assemblies. Penrose, and his collaborator Stuart Hameroff (who also contributes a paper to the volume), think, however, that quantum effects may be effected through intra-cellular structures (microtubules) thereby creating an avenue for large-scale computation. Penrose has the following thoughtful observation: “Indeed, there is no question that if the brain does make use of such “strongly” quantum-mechanical phenomena, it must do so through the agency of some very sophisticated organization. (p.viii)” Life and mind might combine small-scale quantum effects with (classically describable) organizational structure.

Chapter one, by Paul Davies, and Chapter three, by Jim Al-Khalili and Johnjoe McFadden both focus on the possible role QM may have played in the origin of life on earth (OOL). Life may have learned to exploit QM phenomena via natural selection after a classically explainable beginning, but it seems plausible that QM may have been key to life from the start. The complexity of the building blocks of life (as we know it) make it statistically very unlikely that the components randomly came together in a primordial soup as was once suspected. Davies explores a model of a quantum replicator as a precursor; both he and Al-Khalili/McFadden discuss the possibility of a quantum-coherent search algorithm which helped lead to an early replicator. These are interesting ideas, although probably a long way from being confirmed or falsified (I have prior posts on work by Davies and McFadden here and here, respectively).

Chapter 2 is from Seth Lloyd, who stays at 40,000 feet by discussing generally how complexity should be expected to arise in a universe which is inherently quantum-mechanical (see my several posts on Lloyd’s “universe as quantum computer” thesis here).

Models of how photosynthesis likely exploits coherence is the subject of Chapter 4 (with the Engel paper validating broadly the idea); the authors of Chapter 5 present models to help quantify the impact of environmental decoherence in biological contexts. This work seems to sharply delimit the potential for coherence; however other authors argue that dynamic systems can foster insulated sub-spaces larger than what would otherwise seem likely.

A quantum role in DNA mutation and replication is a topic which is discussed in several chapters (6,9,10). It seems accepted that tunneling is one avenue to DNA mutation; possibly QM has a more meaningful role to play. The capabilities of artificial quantum systems are explored in chapters 11-14. To the extent QM systems are good at mimicking features of living things, this offers more circumstantial evidence.

One of my favorite parts of the book is the inclusion (as chapters 15 and 16) of the transcripts of two staged debates which took place at conferences: one is on the future of quantum computing (from 2003), and one specifically on the topic of whether life utilizes non-trivial quantum effects (2004). Both debates featured good insights and a good deal of wit. At one point in the latter debate, one of the participants, Howard Wiseman, offered his definition of a non-trivial quantum effect as “something that will make a biologist want to go out and, you know, take a second year quantum mechanics course and learn about Hilbert spaces and operators, so that they understand what’s going on. (p.358)” Again, I thought about how something like the Engel, et.al. result would change the debate if it were held again today. Wiseman and Jens Eisert --another debate participant -- contributed a thoughtful paper (Ch. 17) explaining in a more organized format why they were on the skeptics’ side of the discussion.

Stuart Hameroff gets the last word in the book, offering his positive proposals for how it all might work (Ch.18). He sees in the structure of cells, both cytoskeleton and protoplasm, features which could lead to a larger scale participatory quantum biology. As a layperson, I’m not a good one to offer judgment; my feeling is that Hameroff presents a string of plausible ideas which nonetheless link together to form a very speculative edifice. On the other hand, as far as I know he could be right! Until we have more attention on the topic we will be slow to sort through and find out which quantum biological ideas are fanciful and which are on target.

So, I second the editors of this volume in their hope that its publication will provoke further debate and help motivate experimental research into this fascinating subject.

Markopoulou: Time is Fundamental, Space is Not

The Foundational Questions Institute has run an essay contest on "The Nature of Time" and received a wide variety of responses. These come from well known physicists, other academics, and amateurs alike. Because of time contraints I've only read a few, beginning with authors I recognized (there are likely some "diamonds in the rough" if one plows through all the contributions).

Fotini Markopoulou of the Perimeter Institute, whose work I mentioned in the last post (and several older ones), wrote: "Space does not exist, so time can." She has a talent for writing clearly about these deep concepts, and I find her arguments persuasive (even if her work toward a full theory of quantum gravity still has a long road ahead). So I highly recommend the essay.

Kudos also to cosmologist and blogger Sean Carroll for his nice essay: "What if Time Really Exists" (here is the Cosmic Variance post introducing it). While I don't like some of his specific suggestions (associating time's arrow with macroscopic entropy considerations), I liked the stance he takes in the essay.

For countervailing views you can read the contributions of Carlo Rovelli and Julian Barbour.

UPDATE (7 January 2009): I just found this interesting post by Scott Aaronson - "Time: Different from space" which includes his computer science-derived insight on why time (causal structure)is fundamental.

Aether Makes a Comeback

The nineteenth century version of the ancient concept of the aether (or ether) was killed by the Michelson-Morley experiment and the success of Einstein’s theory of special relativity. Electro-magnetic radiation needed no substance to support wave propagation. Of course we did not revert to a view of space as an void sprinkled with a few solid objects. In modern particle theory, space-time is pictured as filled with matter fields. And in general relativity, space-time is revealed as a dynamic actor, not just a backdrop. Still, space-time remains distinct from matter/energy, and is geometric, rather than substantive. It thus retains a bit of the conceptual flavor of an empty container (a related discussion on the blog is here).

I was surprised to see the number of physics papers on arxiv which invoke the concept of aether (or ether) in the context of theoretical proposals to solving outstanding problems (e.g. dark energy). For me, aether was brought to mind by certain quantum gravity research programs.These propose that the space-time of general relativity is not fundamental: it emerges (along with the matter fields of the standard model) from something more basic – an underlying network of elementary quantum systems. This underlying network is not itself defined against a spatial backdrop and lacks the usual notions of distance or locality. Both space-time geometry and matter as we know them are constituted by the quantum systems: they arise from the aether.

For an example of this kind of work, here’s the second “quantum graphity” paper from Fotini Markopoulou and colleagues (the authors do not invoke the term aether, so don’t blame them!*). The introduction does a good job of discussing the stance they are taking toward the space-time of general relativity, and places this in the context of how other quantum gravity research programs approach the issue.

* Although they do link their work to the model described in this paper: “Quantum ether: photons and electrons from a rotor model” by Levin and Wen.

{UPDATED 19 November, 2008: Minor edits; 8 December 2008: Sean Carroll at Cosmic Variance just posted about his collaboration on aether field models.}

Ruminating on Theism and Personhood

As I’ve discussed in previous posts (see list below), one can try to put a theistic spin on my concept of the necessarily existing metaphysical “megaverse”: one can identify the megaverse with “God”. To be sure, it would be a non-traditional concept of God compared with that of our Western religious traditions – it would be a variety of panentheism (or perhaps panendeism). But perhaps this is simply stretching things too far, and using the label “God” is simply incongruous. Certainly there may be less room for confusion in communicating the ideas if one leaves “God” out of it (I think the historical reception given to Whitehead’s process metaphysics is a cautionary tale in this respect). While there are several considerations here, I think this decision of labeling should be driven in part by the question of personhood, which seems to be an important component of most conceptions of God.

I have a longstanding skepticism about the attribution of personhood to God -- if personhood means something similar to what it means in the human context. In the context of traditional religions, I always suspected anthropomorphism was at the root of this attribution. In outlining my version of the cosmological argument for a necessarily existing entity, I disliked even using the term “necessary being”, because it has the flavor of “human being”, and thus too readily invokes personhood.

Despite this skepticism, the panentheistic version of my view would say that human characteristics arise from the same raw materials which also constitute God, so there must be some essential affinity. Given my specific opinion that first-person experience is rooted in the most fundamental level of reality, I suspect that God might well be a subject of experience – a key aspect of human personhood.

On the other hand, when discussing Timothy O’Connor’s book (here and here), I disagreed with him on whether the necessary being (NB) needed to be considered an agent (and agency seems to be another key aspect of personhood). It seemed sufficient for the NB to be an impersonal font of creation without need of intentions, purposes, or discrete top-down decision-making. My thought here is that a human being moves within a sea of other beings or systems, and his/her agency arises in this context. The NB is the source and sum of all being, and does not operate in a larger context. This seems to me to be an important difference. To use an analogy: if a human being is an actor, then God is the theater, not another actor.

So, at this point I have a mixed verdict – our human essence is derived from the NB, but our status as a finite subset of the NB’s totality makes our nature very different. Whether the concept of personhood can be stretched to cover both situations is unclear, and I think the better option is to decline to consider the NB to be a person. And this may be a good reason to resist using the label God for what I have in mind.

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Note: I’m even less well-read in relevant literature in this area than in other subjects I discuss: any reading suggestions in philosophy of religion are welcome.
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Post Series (in chronological order): A Philosophical Path to Theism?

Modal Realism and the Cosmological Argument
Exploring the Borderlands
Panentheism
Whitehead's Philosophical Theism
Logos vs. Chaos, Part One
Logos vs. Chaos, Part Two
A Necessary Being or Just a Collection?
Why the Megaverse is a Unified Entity
Is the Megaverse a Subject of Experience?

Finally! (off-topic post)

28 years since the last Phillies championship and 25 years since the last city title in a major sport.

And what a great team. They are a well rounded, solid group of players, with stars we've seen develop over the years as well as clutch role players added recently. Great personalities who've given us wonderful entertainment and now the most satisfaction a fan can get.

Ryan Howard's victory lap -- picture by elisbrown -- flickr under creative commons license.

What Lies Beyond the Big Bounce

We don’t have a fully developed theory of quantum gravity yet, but there is one consequence of the theory we already know: it will banish general relativity’s space-time singularities from our conception of the universe. In particular, the idea of the big bang needs to be retired after decades of dominating professional and popular views of cosmology: the observed universe did not begin as a singularity but rather grew out of a pre-existing reality – a “big bounce”.

Martin Bojowald had a nice article in SciAm recently ("Follow the Bouncing Universe" in the print edition). Bojowald is a loop quantum gravity theorist: while loop theory has not produced an adequate theory for quantum gravity (and I think it probably won’t), it has produced formalisms that may be useful for constructing models which offer insight into the question of what will replace singularities in QG. This work goes under the rubric “loop quantum cosmology (LQC)”. I also noticed that Bojowald’s senior colleague Abhay Ashtekar has a paper out summarizing the results of work in LQC.

What intrigues me is their exploration of what the region on the other side of the big bounce might be like.

In his article, Bojowald first outlines the idea that space-time in QG is not a continuum, but rather has a fine-scale fundamental structure. These space-time “atoms” follow the rules of quantum mechanics and therefore the physics that prevails at high energies/short distances will differ from general relativity (GR). Specifically, in the loop model, a repulsive force comes into play at high energy densities, preventing singularities. In the case of the big bang, one scenario is that the initial high density state arose when a pre-existing universe collapsed (hence – a “bounce”). Bojowald describes an early, simplified, model which seemed to imply that the pre-existing universe was similar to our own. However, Bojowald says his own subsequent work found that quantum effects would have dominated the immediately pre-existing world:

“So the bounce was not a brief push by a repulsive force, like the collision of billiard balls. Instead, it may have represented the emergence of our universe from an almost unfathomable quantum state – a world in highly fluctuating turmoil.”

Bojowald finishes by discussing how we might learn more about the pre-existing universe from astronomical clues.

Ashtekar’s paper discusses the same research more formally; in addition he also deals with LGC models for black holes, where again singularities are replaced by quantum regions (somewhat surprisingly to me, black holes are somewhat more difficult to model than the big bang itself). He concludes his discussion of the big bang/bounce this way: “Big bang is not the Beginning nor the big crunch the End. Quantum space-time appears to be vastly larger than what general relativity had us believe!”

My takeaway is that a realm of quantum possibilia extends beyond and surrounds us our island of observable cosmos. The old idea of the universe as a relatively straightforward, neatly bounded space-time container must be discarded.