Friday, May 1, 2009


“Most of all, we need to preserve the absolute unpredictably and total improbability of our connected minds. That way we can keep open all the options, as we have in the past.”
Lewis Thomas, 1973

This book by Steven Johnson is a good book to read if you’re just getting started on the topic of complexity science or interested in how to build emergent systems.

Reading on complexity is difficult. Words like complexity, and especially chaos, take on different meanings when you are talking about the science of complexity. Authors in the field don’t always agree on what the words mean. This book is on emergence that is a property of complex systems, another complication.

The author identifies Warren Weaver as the originator of the science of complexity in 1948. Weaver wrote an article for the American Scientist that identified the three regions of science that we’re still having difficultly naming. He called the three simplicity, disorganized complexity and organized complexity.

“…Weaver divided the last few centuries of scientific inquiry into three broad camps. First, the study of simple systems: two or three variable problems, such as the rotation of planets, or the connection between an electric current and its voltage and resistance. Second, problems of "disorganized complexity": problems characterized by millions or billions of variables that can only be approached by the methods of statistical mechanics and probability theory. These tools helped explain not only the behavior of molecules in a gas, or the patterns of heredity in a gene pool, but also helped life insurance companies turn a profit despite their limited knowledge about any individual human's future health. Thanks to Claude Shannon's work, the statistical approach also helped phone companies deliver more reliable and intelligible long distance service.

But there was a third phase to this progression, and we were only beginning to understand. ‘This statistical method of dealing with disorganized complexity, so powerful an advance over the earlier two-variable methods, leaves a great field untouched,’ Weaver wrote. There was a middle region between two-variable equations and problems that involved billions of variables. Conventionally, this region involved a "moderate" number of variables, but the size of the system was in fact a secondary characteristic:

Much more important than the mere number of variables is the fact that these variables are all interrelated.... These problems, as contrasted with the disorganized situations with which statistics can cope, show the essential feature of organization. We will therefore refer to this group of problems as those of organized complexity.”

The author describes the five fundamental principles of a system that will learn from the ground up, from local knowledge, and have the likely hood of exhibiting emergence:

• More is different - a critical mass must exist and individuals don’t “know” that they are organizing
• Ignorance is useful – simplicity of rules and language
• Random encounters – decentralized systems rely on random encounters
• Pattern detection – individuals have to be able to recognize patterns
• Interaction with neighbors – local information can lead to global wisdom

Emergence is a phenomena that is easily observable from thermal convection in liquids to the movement of slime mold to ant colonies to the growth of cities to even life itself.

One of the most difficult parts of the emergence paradigm to grasp by humans is that structures emerge without a leader, they are all decentralized, no one is in charge. But the real lesson of this book is that not all large systems of entities will exhibit emergent behavior. They must follow these principles.

Emergence: The Connected Lives of Ants, Brains, Cities and Software
Steven Johnson
Scribner, 2001, 288p

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