There are two principal effects of the Internet on privacy. The first is to shrink personal expression to a dichotomy: public or private. Prior to the rise of digital social life, much of what we said and did was in a public environment — on the street, in a park, at a party — but was not actually public, in the sense of being widely broadcast or persistently available.This enormous swath of personal life, as we used to call it, existed on a spectrum between public and private, and the sheer inconvenience of collecting and collating theoretically observable but practically unobserved actions was enough to keep those actions out of the public sphere.That spectrum has now collapsed — data is either public or private, and the idea of personal utterances being observable but unobserved is becoming as quaint as an ice cream social.