Worlds Hidden in Plain Sight: The Evolving Idea of Complexity at the Santa Fe Institute, 1984–2019 (Compass)

some form of complexity theory is required if we are to understand many of the intimate, and patently uncertain, interactions found in modern society.

This “prey-switching” behavior is common to generalist predators and turns out to be ecologically stabilizing for the whole food web. As generalists turn their attention to different prey species, the species that were getting depleted get a chance to recover, reducing the risk of extinction.

Prices arise from the countless acts of many individuals attempting to trade in various goods. They are an emergent phenomenon.

Another, more intuitive way to understand urban scaling is the speed of life in cities. Life in larger cities is generally faster, meaning one can do more, both good and bad, by having more social exchanges over the same amount of time. This speed of social life is intimately connected to the spatial density of many activities, creating spaces and

Clausewitz himself proposed that war could best be compared with commerce, since both are social conflicts of human interests and activities.

In this sense, cities are an outstanding example of complex adaptive systems: collections of individual constituents (people, in this case) that interact in myriad ways, usually mediated by some sort of network.

This paradox of comprehension was articulated explicitly by a great physicist of an earlier age: “Sir Isaac Newton, when asked what he thought of the infatuations of the people, answered that he could calculate the motions of erratic bodies, but not the madness of a multitude” (quoted from The Church of England Quarterly Review, 1850).

But markets have become highly connected and computerized, so what happens in one market doesn’t stay in one market. Information now flows quickly through the system, and computerized trading algorithms can be programmed to execute trades in the blink of an eye. (Actually, eye blinks take a poky 350 milliseconds, which is slow compared to today’s a

Traditionally, science seeks order by understanding the simplest parts of a system. How does a single gas particle behave given a certain temperature? Which gene in our DNA determines eye color? Scientists then try to develop theories that explain more general observations based on their detailed understanding of the individual parts.