A brilliant, revelatory account of the Cold War origins of the data-mad, algorithmic twenty-first century, from the acclaimed and internationally bestselling author. 'Back in the 1960s, long before the denizens of Silicon Valley were infiltrating every facet of our lives, the smart men and women of The Simulmatics Corporation were creating algorithms to predict and even influence human behaviour. Jill Lepore reveals how this forgotten company invented the data-weapons of the future. If Then is simultaneously gripping and absolutely terrifying' Amanda Foreman 'An authoritative account of the origins of data science, a compelling political narrative of America in the Sixties, a poignant collective biography of a generation of flawed men - Jill Lepore's If, Then represents not only a stunning achievement in itself, but a stirring defence of the humanities in our techno-reductive age' David Kynaston 'A person can't help but feel inspired by the riveting intelligence and joyful curiosity of Jill Lepore. Knowing that there is a mind like hers in the world is a hope-inducing thing' George Saunders, Man Booker Prize winning author of Lincoln in the Bardo 'Jill Lepore is the pre-eminent historian of forgotten tales from America's past that throw startling light on the present. This brilliant book illuminates the future too. The story of the original data science hucksters of the 1960s is hilarious, scathing and sobering - what you might get if you crossed Mad Men with Theranos. It's a reminder, in the age of Cambridge Analytica and whatever comes next, that we have been here before and should know better.' David Runciman