Freedom under the gaze of Big Brother: Preparing the grounds for a liberal defence of privacy in the era of Big Data

'Big Brother is watching you!' the posters in Orwell's Oceania told all its inhabitants. We have no such posters, but we live in the era of Big Data, and someone is watching us. Here, I discuss how Big Data is an omniscient and ubiquitous presence in our society. I then examine to what degree Big Data threatens liberty in both the negative and positive conception of the term. I arrive at three propositions: a) Big Data threatens privacy and enables surveillance, b) the lack of alternatives to lifestyles that involve feeding into Big Data leads to something akin to forced participation in the surveillance of Big Brother, and c) surveillance and lack of privacy are a threat to freedom, because i) the information gathered can be abused, ii) people have a right not to be observed (even if the surveillance is completely benign), and iii) being observed is an intervention that can affect those who are observed. Together, these propositions lead to the conclusion that Big Data threatens liberty. I argue that the positive conception of liberty provides the strongest argument against how we currently employ Big Data, but that the negative conception can also provide a sufficiently strong argument. On this basis, a liberal defence of privacy, and thus also of liberty, against this new form of surveillance can be established.