Monday, April 30, 2007

Physical Systems Process Information: So What?

Seth Lloyd’s book (see prior post) has a nice passage in a chapter subsection entitled “So What?” (p. 168). If the universe can indeed be viewed as a quantum computer, why should we care? He poses this further question: “Do we really need a whole new paradigm for thinking about how the universe operates?” Lloyd says (and it would seem difficult to disagree) that the dominant paradigm of the age of science has been that of universe as mechanism. He proposes a new paradigm: “I suggest thinking about the world not simply as a machine, but as a machine that processes information (p.169 – emphasis original).” In my opinion, however, Lloyd’s discussion, while often suggestive, doesn't really answer the "so what" question. Actually, he underplays how radical and interesting a notion this new paradigm really could be.

Unfortunately, in the section quoted from above, Lloyd doesn’t follow through in offering a philosophically compelling interpretation of this new paradigm. He goes on to discuss how the view might better (technically) account for complexity and how it could help on the quest for a theory of quantum gravity – both topics of subsequent sections. Other statements of this sort sprinkled throughout the book are neutral in tone and vague in terms of what they really mean. Here’s the typical quote: “All physical systems register information, and when they evolve dynamically in time, they transform and process that information. (Prologue, p. xi.)”.

I became frustrated at this: What does it really mean to say physical systems process information? In my own (perhaps uninformed) view of classical computing, the only true information processors are the human beings who provide input, program, and interpret the output. The semantics of information processing are provided by humans exclusively, the rest is syntax. This issue is discussed in one subsection of Lloyds’ book, entitled “Meaning” (p.24), where Lloyd relates being asked by a student: “’But doesn’t information have to mean something?’” The response: “’You’re right that when we think of information we normally associate it with meaning,’ I answered. ‘But the meaning of ‘meaning’ is not clear.’” In the rest of the section (written presumably after some reflection on this), he fails to improve on this answer. He discusses how bits can represent information, and then says “the interpreter must provide the meaning.” Note there is nothing innovative or even quantum mechanical about this discussion.

Here’s the unstated radical interpretation of Lloyd’s theory: If physical interactions ubiquitously can be described in terms of information processing, this implies that something we think belongs uniquely to human (and some animal) agents is also a feature of more elementary physical systems: that is, possession of semantic properties, or intentionality. If one is unwilling to take this step, that’s fine, but then there is no important difference between the new and the old paradigm when it comes to interpreting how human life and mind can fit into the picture of an otherwise lifeless mechanistic universe.

It’s not a coincidence that Lloyd’s approach to the measurement problem of QM is conservative. He believes the decoherent-histories approach is practical and useful enough to de-emphasize worries about foundational interpretation.


corvo said...

Somewhat offhandedly, but pointedly, you wrote: “The semantics of information processing are provided by humans exclusively, the rest is syntax.” Ah, yes – semantics, meaning, and all that, particularly as they inform your “radical interpretation of Lloyd’s theory”, in which you conclude: “...this implies that something we think belongs uniquely to human (and some animal) agents is also a feature of more elementary physical systems: that is, possession of semantic properties, or intentionality”. Well....

Much as Einstein trumped Newton’s “hypotheses non fingo” with his demonstration that “gravitation” does not require “gravity”, I would first like to suggest that “meaningfulness” qua observed phenomenon does not require “meanings” qua real (albeit abstract) entities. More pithily perhaps: semantics is an illusion.

Of course, like “the mind” and other obdurate superventions, semantics is a useful illusion, but an illusion nonetheless, in that all the real work is actually done by something else, viz. syntax. As conventional theory and practice both would prefer, it is difficult to see how this can be so, but critically, it is not impossible to see this (as my work in natural language processing clearly shows – I’m not merely being cranky) just as it is possible to comprehend how bacterial chemotaxis is a qualitatively (but certainly not quantitatively) sufficient model of all biologically hosted behavior – human included. Indeed, just as playing the God card is an illegal move in any intellectually honest attempt to understand reality, so too it will become realized, after much diligent toil, that appealing to semantics, or souls, or abstract entities of any kind, is cheating. Even worse, however convenient or well-intentioned it may be, such conceptual pandering is fundamentally misleading, providing one is really concerned with understanding how things are and how they work. Not why, but how.

Since time immemorial, people (including such intellectual heroes as Aristotle) have been misled by sheer observation into believing all sorts of nonsense, such as the sun orbiting the earth, because it seems “natural”; but as Wittgenstein was fond of pointing out: How would it appear if the earth orbited the sun? Similarly, it appears that semantics is required for language processing and the like, but how would it appear if syntax actually suffices? Our brains allow us to imagine minds, but that doesn’t mean that we need them for anything but conversational convenience.

As Turing opined, intelligent is as intelligent does. Since comment demands brevity, I can only posit without sufficient reason that it is simply not possible for any mechanism which is “materially indistinguishable” from an intelligent/conscious/possible/etc. replica to be distinguishable from its putatively endowed other in any manner. Zombies aren’t possible critters simply because there is nothing for a zombie to lack once all the material gizmos are in place. Synthetic biology, artificial life and the like will merely confirm what natural selection has already and amply demonstrated: strict materialism works. Just give it (another) chance ... but this time, let’s pay attention so that we don’t get fooled again.

Disclosure: I was (in a previous incarnation) a (not particularly orthodox) student of David Lewis.

Steve said...

Thanks for your thoughts, Corvo.

I still disagree. Whitehead called this problem “the fallacy of misplaced concreteness”. We take the third-person mathematical and symbolic descriptions of nature and start to believe that that they are somehow all that is real. Therefore the parts of reality associated with first-person experience must be an illusion.

This is a mistake. And it doesn’t mean that we need to appeal to the supernatural. It just means that nature is a bit richer than the descriptions. As nature gives rise to living things, such as animals and humans, they derive their first-person intentionality and subjective awareness from the fact that the fabric of the world already possesses the ingredients to make this happen when things are put together in the right way.

Note this doesn't change the course of science in figuring out how things work - we're not talking about intelligent design here. It's just that the most primitive irreducible part of science, which is the quantum measurement event, contains the seeds of experience and semantics.

cuanalo said...

Meaning has a very simple principle and it pertains in general to life and moreover to self-conscious living creatures such as ourselves. From the advances in Arsology we see that life is a will-of-form or the will to preserve a form, in any living creature chemical processes vary and the constituent matter vary in time, the only constant is the form (not the figure) of being which is also the object of reproduction.

Thus meaning can be defined by the potential outcome of any given configuration of information (phenomenon) as related to the preservation of this form. In biological terms then meaning is basically of only three types: conducive, threatening or indifferent,

In humans, through the migration from the biological to the artificial (culture) meaning seems to become more complex, but in the end it is just an extension of the biological principle of preservation of biological form to the artificial principle of the preservation of cultural form.

Steve said...

Thank you. The idea of meaning being based on will to preserve form is an interesting one. Perhaps it can be applied to non-living physical systems as well.