CAN THE COMPLEXITY GURUS EXPLAIN IT ALL?
By John H. Holland
Addison-Wesley 185pp $24
AT HOME IN THE UNIVERSE
By Stuart Kauffman
Oxford 321pp $25
For all its accomplishments and vaunted brainpower, the human species still faces myriad mysteries--and problems. No one has yet managed to figure out how life began, how to keep ecosystems healthy, why new diseases such as AIDS emerge, how the economy really works, or how to cure the ills of America's inner cities. But since the late 1980s, in a display of courage, or perhaps of hubris, a group mf scientists at the Santa Fe Institute in New Mexico has tried to tackle these questions from a fresh perspective: the science of complexity. Part of their story has already been chronicled in an entertaining--if breathless--1992 book by science writer M. Mitchell Waldrop. Now, two of the scientists themselves are providing the latest word on the search for deeper meaning.
Their basic idea: All of these questions arise in what might be called "complex" systems, such as ecosystems or the economy. Instead of trying to puzzle out the workings of one system, why not find general laws that underlie all these systems? Understanding what makes all of them tick "would, in turn, provide us with guidelines for effective approaches to...problems such as immune diseases, inner-city decay, industrial innovation, and the like," explains University of Michigan computer scientist and MacArthur fellow John H. Holland in his slim, dense Hidden Order.
The idea of general laws capable of explaining systems as disparate as a sprawling city or the delicate development of an embryo is seductive--and controversial. Yet the claims by the complexity gurus don't stop there. In his exuberant new book, At Home in the Universe, University of Pennsylvania biologist and fellow MacArthur "genius" Stuart A. Kauffman argues that these fundamental laws create a "spontaneous order [that] is enormously greater than we have supposed." Just as the known laws of physics dictate a snowflake's exquisite six-pointed symmetry, he suggests, this natural order explains everything from the superiority of democracy and the path of technological development to the existence of life itself.
To Kauffman, whose tome careens back and forth between mathematical treatises and bull-session-like musings, the notion is tantamount to a religious conversion. No longer must we believe that life--or humankind--is a mere accident of evolution. The new science, he asserts, "may help us find anew our place in the universe...recover our sense of worth, our sense of the sacred..."
At the heart of such bold pronouncements is the conviction that computers offer a new and unique window into the real world. If simple mathematical rules can give rise to complex behavior in computer simulations, the reasoning goes, then similar rules may also apply to systems such as the economy.
Holland expands on this idea by first presenting an analysis of the characteristics shared by all complex systems. For example, nerve cells and companies alike might well be thought of as independent "agents." Each agent operates in groups as well as individually, participating in flows of information or goods. Each agent also has internal "goals" but can adapt to new surroundings. Holland then shows how agents' properties can be described by computer algorithms.
Kauffman casts a wider net. In sections that are tough going, he describes mathematical simulations of collections of chemicals, networks of genes, and systems that evolve in a way that boost the "fitness" of both individuals and the overall system.
Much of this work is on the cutting edge of computer science. Some of the results are tantalizing. Holland describes a stock-market simulation that he says mimics crashes and speculative bubbles better than classic models. Other simulations successfully model biological races to develop defenses and show that cooperation, with occasional bluffs, is the most effective strategy in a group.
But what most excites Kauffman is the notion that life is the inevitable result of nature's hidden order. His analyses of networks of interacting genes, for instance, show that the systems spontaneously organize themselves into just a few configurations. More evidence comes from simulated soups of chemicals, in which each substance is given the ability to catalyze other reactions. Almost magically, the soups create clumps of chemicals capable of replicating themselves--eerily reminiscent of real life. When he discovered these phenomena, "I knew that God had revealed to me a part of how His universe works," Kauffman gushes in Waldrop's book, Complexity, still the most readable account of the new science and its personalities.
These computer simulations are siliconic tours de force. But are they really uncovering general laws or new insights into humanity's problems? Neither book quite delivers on these grandiose claims. Holland's explanation for the lack of results: "We are only at the beginning of the search for general principles." Kauffman formulates a few general laws, but they're disappointingly trite. For instance, he says, models that resemble a company interacting with customers reveal that "you should not try to please all of the people all of the time, but you should pay attention to everyone some of the time!"
Not surprisingly, such examples are fueling skepticism about the central premise of computer-based complexity studies. Just because a simulation looks like a real phenomenon doesn't mean the mathematical rules that generate the simulation also underlie--and explain--real life. For instance, Kauffman's assertion that the striped patterns arising in broths of organic chemicals "may foretell the stripes of the zebra" is about as logical as saying that a lamp tells us something important about the sun, since they both produce light. Sadly, rules that apply to all complex systems are probably so general that they're useless in explaining how any one particular system works.
What's more, Kauffman's grandest claim--that life is the inevitable consequence of fundamental laws--remains unsupported. If "a metabolism will crystallize from the broth...whenever a collection of chemicals contains enough different kinds of molecules," as he asserts, then why did life apparently emerge only once in the earth's long history? And if these laws provide "order for free," as Kauffman repeatedly says, why did it take 3 billion years for single-celled creatures to evolve into more complex organisms? Kauffman remains unfazed by these uncomfortable facts, predicting that proof for his theory could be only a few years away. "We are hunting big game, seeking laws of complexity," he trumpets. The quarry may be more elusive than Kauffman believes, but it's still a provocative quest.BY JOHN CAREY