Open source, open government, open culture – as Nate Tkacz, PhD at the University of Melbourne points out in his talk at the Economies of the Commons Conference, the ubiquity of ‘openness’ as a master category of politics in network cultures turns into a multidimensional, and even more into a political term in the debate on the free and open. With referring to historical notions of openness, Tkacz makes some critical statements on the function of the open with particularly discussing it on the basis of Karl Popper’s work on ‘The Open Society and its Enemies”.