Could Big Data have prevented 9/11? Perhaps—Dick Cheney, for one, seems to think so. But let's consider another, far more provocative question: What if 9/11 happened today, in the era of Big Data, making it all but inevitable that all the 19 hijackers had extensive digital histories?
It used to be that one's propensity for terrorism was measured in books or sermons. Today, it's measured in clicks. It's not that books or sermons no longer matter—they still do—it's just today they are consumed digitally, in a way that leaves a trail. And that trail allows us to establish patterns. Are the books you bought on Amazon today more radical than the books you bought last month? If so, you might be a person of interest.
The Tsarnaev brothers, who allegedly bombed the Boston Marathon earlier this year, are of this new breed of terrorists. The brothers felt at home in the world of Twitter and YouTube. And some of the videos reportedly favorited by Tamerlan, the older brother, are clearly of extremist nature. Had someone been analyzing the brothers' viewing habits in real time, a great tragedy might have been averted.
The good news—at least to Big Data proponents—is that we don't need to understand what any of these clicks or videos mean. We just need to establish some relationship between the unknown terrorists of tomorrow and the established terrorists of today. If the terrorists we do know have a penchant for, say, hummus, then we might want to apply extra scrutiny to anyone who's ever bought it—without ever developing a hypothesis as to why the hummus is so beloved. (In fact, for a brief period of time in 2005 and 2006, the FBI, hoping to find some underground Iranian terrorist cells, did just that: They went through customer data collected by grocery stores in the San Francisco area searching for sales records of Middle Eastern food.)
The great temptation of Big Data is that we can stop worrying about comprehension and focus on preventive action instead. Instead of wasting precious public resources on understanding the “why”—i.e., exploring the reasons as to why terrorists become terrorists—one can focus on predicting the “when” so that a timely intervention could be made. And once someone has been identified as a suspect, it's wise to get to know everyone in his social network: Catching just one Tsarnaev brother early on may not have stopped the Boston bombing. Thus, one is simply better off recording everything—you never know when it might be useful.
Gus Hunt, the chief technology officer of the CIA, said as much earlier this year. "The value of any piece of information is only known when you can connect it with something else that arrives at a future point in time,” he said at a Big Data conference. Thus, “since you can't connect dots you don't have … we fundamentally try to collect everything and hang on to it forever." The end of theory, which Chris Anderson predicted in Wired a few years ago, has reached the intelligence community: Just like Google doesn't need to know why some sites get more links from other sites—securing a better place on its search results as a result—the spies do not need to know why some people behave like terrorists. Acting like a terrorist is good enough.