The Guardian view on internet privacy: it’s the psychology, stupid | Editorial

The ease with which giant databases can be queried and cross-referenced makes privacy vanish on the internet

Privacy is necessary for human society to function. The problem is not that the information exists but that it reaches the wrong people. Information on the internet could bring great benefits to society, and to individuals, when huge datasets can be refined to yield information otherwise unavailable. But once the information is gathered, a precautionary principle has to apply. It is too much of a stretch to agree with John Perry Barlow, the internet rights pioneer who died this week, when he quipped that "relying on the government to protect your privacy is like asking a peeping tom to install your window blinds"; but it does not help when it appears that everything the public sector does with the huge datasets it has will be overseen by the minister for fun.

Governments need to keep our trust; but technology erodes privacy in two ways. The first is simply smartphones. Most Britons - 70% - now carry around with them devices which record and report their location, their friends and their interests all the time. The second is the ease with which two (or more) datasets can be combined to bring out secrets that are apparent in neither set on its own, and to identify individuals from data that appears to be entirely anonymised. By the beginning of this century researchers had established that nearly 90% of the US population could be uniquely identified simply by combining their gender, their date of birth and their postal code. All kinds of things can be reliably inferred from freely available data: four likes on Facebook are usually enough to reveal a person's sexual orientation.