Monday, February 18, 2008

A brief history and critic of complexity theory

This is a brief history synthesized by E. O. Wilson in Consilience of the accomplishments and promises of the science of complexity as well as its present drawbacks and its objectives needed to be fulfilled to convince a larger portion of the science community.

"Complexity theory was born in the 1970s, gathered momentum in the early 1980s, and was envelopped in controversy by the mid-1990s. The issues of contention are almost as tangled as the systems the theorists hoped to unravel. I think it possible to cut to the heart of the matter, as follows. The great majority of scientists, their minds focused narrowly on well-defined phenomena, do not care about complexity theory. Many have not yet heard of it. [...] Those who care can be divided into three camps. The first comprises a heterogeneous scattering of skeptics. They believe that brains and rain forests are too complicated ever to be reduced to elementary processes, let alone reconstituted in a manner that predicts the whole. Some of the skeptics doubt the existence of deep laws of complexity, at least any that can be grasped by the human mind.

In the second camp are the fervent advocates, a band of audacious complexity theorists, exemplified by Stuart Kauffman (author of the The origins of order) and Christopher Langton, who work at the Santa Fe Institute in New Mexico, unofficial headquarters of the complexity movement. They believe not only that deep laws exist but that their discovery is on the near horizon. Some of the essential elements of the laws, they say, are already emerging from mathematical theories that use exotic conceptions such as chaos, self-criticality, and adaptative landscapes.[...] Their grail is a set of hoped-for master algorithms that will speed passage from atom to brain and ecosystem, consistent with reality but requiring far less factual knowledge than would be needed without the algorithms.

The third group of scientists, of which I am a reluctant member, has settled along positions strung between the two extremes of rejection and unbridled support. I say reluctant, because I would like to be a true believer: I really am impressed by the sophistication and élan of the complexity theorists, and my heart is with them. But my mind is not, at least not yet. I believe with many other centrists that they are on the right track -but only more or less, maybe, and still far short of success. [...] The basic difficulty, to put the matter plainly, is an insufficiency of facts. [...] The postulates they start with clearly need more detail. Their conclusions thus far too vague and general to be more than rallying metaphors, and their abstract conclusions tell us very little that is really new.
[...]
None of the elements of complexity theory has anything like the generality and the fidelity to factual detail we wish from theory. None has triggered an equivalent cascade of theoretical innovations and practical applications. What does complexity theory need to be successful [...]?

Complexity theory needs more empirical information."
Edward O. Wilson, Consilience (Chapter 5)

Obviously, this discussion needs to be continued and I will keep posting critics and successes of complexity theory.

1 comment:

Cedric said...

And you, in which camp are you ?
For me, I would say that I am in the third camp, like the author: I learned about complexity theory a long time ago, when I was in the "classes préparatoires", but I did not become fascinated by it. Maybe because I did not really understand it...