Re: The Relevance of Complex Systems

From: Tennessee Leeuwenburg (
Date: Thu Sep 08 2005 - 20:03:07 MDT

Hash: SHA1
Joel Peter William Pitt wrote:

> On 9/8/05, *Eliezer S. Yudkowsky* <
> <>> wrote:
> My car, alas, is not a Carnot Engine. There are all these
> practical complications in the real world, doncha know, which makes
> thermodynamics irrelevant if you're trying to build *efficient*
> systems. My car is a Complex System, too: I looked under the hood
> and there were all these interacting doohickeys whose local
> behavior was completely different from the globally emergent car.
> That carburetor thingy doesn't even have wheels, much less an
> engine! As a result I find myself completely unable to predict my
> car's behavior. Why, one time I floored the gas pedal, and my car
> moved fifty miles backward and refilled its own gas tank!
> If you observe the states of the individual components they will be
> changing in a semi cyclic manner, the system will be expending
> energy (fuel) to maintain these state changes. The states will not
> be completely stable or nothing interesting would happen, the
> states are not completely chaotic either or the desired behaviour
> of the car wouldn't be acheived.
> When one tunes a car you adjust timing and other variables in order
> to get the emergent behaviour of a working car, too far from the
> right values and the car/system doesn't work (A untuned car can
> sound like chaos too :P)
> Joel

I don't think that's a proper description of what chaotic is. Chaos
doesn't mean "without rules", but rather it means that the behaviour
of the system is obviously derivable from the rules. The states are
chaotic in that it would be exceedingly difficult to predict from
knowledge of the initial conditions of the system what the precise
state of the system would be sometimes in the future. The
predictability of a car comes not from a bottom-up understanding of
all interacting components, but rather from grokking what the stable
patterns are.

Chaos theory, insofar as I qualitatively understand it, is all about
that kind of behaviour. It is not just a blanket claim that "you can't
understand complex things", but rather that the right way of thinking
about complex systems is in terms of stable and unstable patterns, etc.

Whether a car really is a complex system or not, I agree, is a pretty
flimsy kind of claim, because its' components are too predicable. But
certainly thinking about a car's details -- such as which piston will
fire at time X, what the oil level will be etc etc is the kind of
specific claim that chaos theory says is impossible. Saying that the
pistons fire to drive the main shaft is the kind of "pattern"
behaviour that chaos theory talks about. It's difficult to address the
fine details, and easy to analyse the super-behaviour of the systems.

- -T
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