The Darkening Web: The War for Cyberspace by Alexander Klimburg Penguin, 420 pp., $30.00

The big Silicon Valley technology companies have long been viewed by much of the American public as astonishingly successful capitalist enterprises operated by maverick geniuses. The largest among them—Microsoft, Apple, Facebook, Amazon, and Google (the so-called Big Five)—were founded by youthful and charismatic male visionaries with signature casual wardrobes: the open-necked blue shirt, the black polo-neck, the marled gray T-shirt and hoodie. These founders have won immense public trust in their emergent technologies, from home computing to social media to the new frontier, artificial intelligence. Their companies have seemed to grow organically within the flourishing ecology of the open Internet.

Within the US government, the same Silicon Valley companies have been considered an essential national security asset. Government investment and policy over the last few decades have reflected an unequivocal confidence in them. In return, they have at times cooperated with intelligence agencies and the military. During these years there has been a constant, quiet hum of public debate about the need to maintain a balance between security and privacy in this alliance, but even after the Snowden leaks it didn’t become a great commotion.

The Big Five have at their disposal immense troves of personal data on their users, the most sophisticated tools of persuasion humans have ever devised, and few mechanisms for establishing the credibility of the information they distribute. The domestic use of their resources for political influence has received much attention from journalists but raised few concerns among policymakers and campaign officials. Both the Republicans and the Democrats have, in the last few election cycles, employed increasingly intricate data analytics to target voters.

Private organizations, too, have exploited these online resources to influence campaigns: the Koch brothers’ data firm, i360, whose funding rivals that of both parties, has spent years developing detailed portraits of 250 million Americans and refining its capacities for influence operations through “message testing” to determine what kinds of advertisements will have traction with a given audience. It employs “mobile ID matching,” which can link users to all of their devices—unlike cookies, which are restricted to one device—and it has conducted extensive demographic research over social media. Google’s DoubleClick and Facebook are listed as i360’s featured partners for digital marketing. The firm aims to have developed a comprehensive strategy for influencing voters by the time of the 2018 elections.

Only in recent months, with the news of the Russian hacks and trolls, have Americans begun to wonder whether the platforms they previously assumed to have facilitated free inquiry and communication are being used to manipulate them. The fact that Google, Facebook, and Twitter were successfully hijacked by Russian trolls and bots (fake accounts disguised as genuine users) to distribute disinformation intended to affect the US presidential election has finally raised questions in the public mind about whether…