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Mathematician Cathy O’Neil’s book shows how numbers can be used to oppress, divide classes

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"I'm trained as a mathematician, and I love math," said Cathy O'Neil, whose new book, "Weapons of Math Destruction: How Big Data Increases Inequality and Threatens Democracy," is an urgent critique of what she describes as the rampant misuse of math in nearly every aspect of our lives. From job applications that rise or fall on an candidate's credit score, to algorithms that determine what ads you see when you go online, math is increasingly used, O'Neil said, as a weapon that too often goes unquestioned, even unnoticed, by most of us.

After receiving her PhD from Harvard, O'Neil said, "I made the mistake — made the decision, I should say — of going into finance in 2007." She soon found herself disillusioned by, among other things, the triple-A ratings that allowed mortgage-backed securities to proliferate, leading to the financial crisis from which we're still recovering. "I thought mathematics was something beautiful, something that provided clarity," she said. "But these ratings were obfuscating, rather than clarifying. They were mathematical lies."


O'Neil began to take note of "arbitrary and statistically unsound" algorithms that were used in high-stakes decisions in education, employment, and the criminal justice system.

"It hit me," O'Neil said, "that the goal was to segregate people by class, to give opportunities to some, and to prey on the most vulnerable. What I've tried to do with this book is explain that there's absolutely nothing inherently fair or morally neutral or objective about algorithms. These algorithms are used to wield real power, through intimidating, mathematically authenticated, pseudo-scientific objectivity."

O'Neil, who recently launched a Columbia University program on data journalism, said she hopes her book will make the general public aware of the role data plays in our lives. Fellow data scientists, she added, must "acknowledge their own ethical obligations" in a world where one wrong number can mean all the difference.


O'Neil will read 7 p.m. Monday at Harvard Book Store.

Kate Tuttle, a writer and editor, can be reached at kate.tuttle@gmail.com.