Openness has become fashionable. Governments, software and even humans are furnished with the adjective 'open'. This is not a quiet and modest adjective, but entails a demanding cluster of requirements. To be open means to be transparent, responsible, accountable and inclusive. In other words: to be open is to be good. 1 What does this mean for science? If we understand openness as the commitment to make the tools and processes of science replicable and open to scrutiny, then science has had a particularly close relationship with openness from its earliest beginnings. It is true that science has been, and still is, to a large extent an elite activity. But the idea that people other than those involved in the creation of a scientific finding need to be able to scrutinise claims in order to find possible errors and to corroborate or falsify hypotheses and claims is intrinsic to the very concept of science. It is the requirement of transparency, intelligibility (if only to peers) and openness to scrutiny that distinguishes science from other instances of skilful practice or from an informed debate. Openness about how we arrive at conclusions on the basis of evidence is what enables the type of empirical self-corrective knowledge creation that science has (often rightly) claimed to be. Why is it, then, that openness-in science, but also in other domains of life-has become such a buzzword in the twenty-first century? There