Big data is poised to transform society, from how we diagnose illness to how we educate children, even making it possible for a car to drive itself. Information is emerging as a new economic input, a vital resource. Companies, governments, and even individuals will be measuring and optimizing everything possible.

But there is a dark side. Big data erodes privacy. And when it is used to make predictions about what we are likely to do but haven’t yet done, it threatens freedom as well. Yet big data also exacerbates a very old problem: relying on the numbers when they are far more fallible than we think. Nothing underscores the consequences of data analysis gone awry more than the story of Robert McNamara.

But, God, he could be a dick. Those who knew Jobs best and worked with him most closely – and I have talked to hundreds of them over the years – were always struck by his abrasive personality, his unapologetic brutality. He screamed, he cried, he stomped his feet. He had a cruelly casual way of driving employees to the breaking point and tossing them aside; few people ever wanted to work for him twice. When he fathered a daughter with his longtime girlfriend Chrisann Brennan at age 23, he not only denied his paternity, he famously trashed Brennan in public, telling Time in 1983 that “28 percent of the male population of the United States could be the father.” His kinder side would only emerge years later, after he had been kicked around, beaten up, humbled by life. He grew up poor, an adopted kid who felt cast aside by his birth parents, feeling scrawny and teased and out of place, and he remained deeply insecure for most of his life, certain that it would not last long.