HE IMPOSING TORRE del Mangia is a 289-foot tower rising over Siena's city hall. Below, the Piazza del Campo serves as the Tuscan town's market square, civic meeting place, and entertainment venue. Together they form the metaphor in the title of The Square and the Tower, the British historian Niall Ferguson's new book about networks, hierarchies, and how they have interacted throughout history.
How hierarchies operate is not a conceptual mystery. The emperors of Rome, the caliphs of Islam, the autocrats of the Kremlin, the armies of Napoleon and Eisenhower, the corporate managers of General Motors, the bosses of the Teamsters Union: In each case we see a Mr. Big at the top of the tower directing lieutenants, satraps, prefects, and legates, all the way down to the grunts at the bottom. Hierarchies arose at the beginning of human civilization, but the "zenith of hierarchically organized power," Ferguson writes, "was in fact the mid-20th century--the era of totalitarian regimes and total war."
Yet hierarchies do not rule perpetually without challenge. Ferguson argues that since 1446, three disruptive changes have made it increasingly easy for large numbers of people to interact and collaborate over time and space--that is, to network. The first was the printing press, whose output swept across 15th century Europe and then beyond. The next was the 19th century telegraph cable, which allowed messages to flow from London to Bombay in four minutes. (The telephone, the fiber optic cable, and the satellite download dramatically accelerated this revolution.) The third change is the instantaneous communication of the internet.
Networks are obscure, ephemeral, clandestine, acephalous, and potentially subversive, built around nodes connected by "edges" to other nodes in a manner that produces activity without centralized control. As in Ferguson's "square" metaphor, they are flat, dispersed, and operate beneath or apart from a tower-like superstructure. Moreover, networks can be part of other networks--and they can be created, manipulated, captured, and annihilated by hierarchies. The Russiagate scandal, for example, hinges on the idea that the leaders of the Russian hierarchy have supported and manipulated a network of largely autonomous cyber-trolls.
Ferguson produces several examples of hierarchies defeating challenges from networks. Take Lenin and Stalin's relentless crackdowns after the Bolshevik Revolution. Their regime shrilly denounced any...