But they are wrong. Because of technological advances and the sheer amount of data now available about billions of other people, discretion no longer suffices to protect your privacy. Computer algorithms and network analyses can now infer, with a sufficiently high degree of accuracy, a wide range of things about you that you may have never disclosed, including your moods, your political beliefs, your sexual orientation and your health.
There is no longer such a thing as individually “opting out” of our privacy-compromised world.
The basic idea of data inference is not new. Magazine subscriber lists have long been purchased by retailers, charities and politicians because they provide useful hints about people’s views. A subscriber to The Wall Street Journal is more likely to be a Republican voter than is a subscriber to The Nation, and so on.”