Concerns about privacy pervade human life, especially with the enormous growth of information and communication technologies over the past few decades. Unsurprisingly, the notion of privacy is being studied by a variety of disciplines, ranging from sociology and anthropology, to law and philosophy. Yet, despite all this attention on ‘privacy’, what exactly privacy amounts to remains less than clear. A similar story can be told for the notion of ‘secrecy’. We probably all have our secrets – smaller ones or bigger ones – but how exactly we should understand the notion of a secret remains, again, less than clear.

Apart from the question what privacy is and what secrecy is, we might also ask why one might want to protect one's privacy and why one might want to have secrets. Intuitively, one main reason why one might want to protect one's privacy is that one doesn't want certain others to acquire knowledge of certain private facts about oneself. And one main reason why one might want to keep certain things secret is that by allowing others to acquire knowledge of this particular fact, we might come to harm of some sort. We don't want just anyone to know just anything about us: we want to be able to control which persons obtain knowledge of which private or secret facts about ourselves in which contexts. Put differently: we don't want to be known to the same degree by just anyone in any old situation.

Despite the intuitive connection between ‘privacy’, ‘secrecy’ and ‘knowledge’, it is interesting to note that in the literature on privacy and secrecy, scholars have thus far not taken advantage of the perspective of the philosophical discipline that studies knowledge (epistemology), and that epistemologists have likewise paid virtually no attention to privacy. An ‘epistemology of privacy’ and ‘an epistemology of secrecy’ are non-existent. There thus seems to be a mismatch between the sort of phenomena privacy and secrecy are, namely epistemic phenomena, and the research on privacy and secrecy that does not frame privacy in those specifically epistemic terms.

The papers in this special issue of Episteme aim to rectify this omission. They all deal with various aspects of privacy and secrecy from the point of view of epistemology. They thus try to connect epistemology to very important topics in our digitalized age. The papers collected in this issue were all presented at the 2012 Episteme conference at Delft University of Technology (the Netherlands). I am grateful to all who presented their research on this occasion and who helped made this conference a very exciting event. I am especially grateful to the referees who carefully read and commented on submitted papers and to the editor of Episteme, Alvin Goldman, for encouragement throughout.