[Matthew Battles is one of my favorite thinkers about how we read, consume, and learn. He’s reading and reacting to Clay Shirky’s Cognitive Surplus and Nicholas Carr’s The Shallows. Over the next several weeks, we’ll be running Matthew’s ongoing twin review; here are parts one, two, three, four, and five. — Josh]

It’s a common belief that the average human uses a mere 10 percent of her total brain power. Of course, it’s a myth. “Brain power,” after all, is an impossible quality to define. Are we talking about the kinds of things Mensa tests for, such as computational ability, spatial intelligence, and logical acuity? Do we mean artistic genius, emotional intelligence? And how do we separate these things from the social expression of thinking, the emergence of powerful new ideas and cultural forms, the rebooting of beliefs and ethical norms? Even (and perhaps especially) in brain science, the terms are constantly shifting — as in recent research suggesting that the ratio of glial and neuronal cells is roughly equal, and that glial cells aid intervene in cognition to a previously unknown extent. Most authorities agree that while a small percentage of neurons are firing at any given moment, over the course of a day the brain is active throughout its entire cellular complement. We use the whole brain — even if not always to our own satisfaction.

While Shirky never mentions it, the 10-percent meme haunts the notion of the cognitive surplus — the linchpin of Shirky’s argument, which remains murky throughout the book. In fact Shirky is not talking about free cognitive power or brain cycles per se, but free time — time we may choose to spend on cognitive or creative work, but which may be spent in other ways as well. Eighteenth-century Britons, in Shirky’s telling, spent newfound funds of time getting pissed on gin. (It’s worth pointing out that this is a very selective view of the 1700’s, and the passages in which Shirky discusses gin are unsourced.) If the tools to make use of spare time — not only gin but religion, books, and newspapers, to name a few — seem crude by our lights, so too were the machinations that princes and politicians could undertake to bend spare cycles to their own ends. As our tools for sharing and creating grow more sophisticated, it becomes crucial that we understand whose purposes they truly serve.

Surpluses are complicated things. In a post dark with foreboding, Quiet Babylon’s Tim Maly quotes Ira Basen of the CBC’s Media Watch column on the effects of a surplus of quasi-journalistic documentation at the G20 protests in Toronto: “Perhaps the best way of understanding police behaviour,” Basen writes, “is to recognize that almost everyone in that crowd had some sort of camera-equipped mobile device, which meant that, in the minds of the police, almost everyone was a potential journalist. That meant they could either give special treatment to everyone or to no one. They chose no one.” Maly follows Basen’s logic to its scary ends:

In a network of cheap ubiquitous sensors, any given node becomes disposable. At highly documented events, the rate at which recordings are made far outstrips the rate at which we can view them. Any given photo or video can be lost but the loss is not that great. Any given observer can be beaten, arrested, even killed, and the loss is not that great. At least not that much greater than if it was any other participant.

This is the terrifying endpoint that Basen does not reach. When everyone is a journalist, not only do their fates no longer warrant special attention by the people being covered, their fates no longer warrant special attention by the people consuming their work.

There’s much to be celebrated in the technological changes that have driven the costs of recording, broadcasting, and publishing towards zero. But we do well to remember that with surplus comes expendability. Basen’s concerns notwithstanding, the danger is less to professional journalism than the nature of the public sphere: the prospect that, faced with the potential marginal costs of spending our cognitive surpluses on oversight, witness, and commentary, we nodes in the network will choose to stick to LOLcats and fanfiction.