Social Network Sites such as Facebook have the capacity to revolutionize public discussion as they encourage citizens to participate in politics and to engage with politicians. However, simply the fact that there is public discussion on policy issues, about political actors, on election campaigns etc., says yet nothing about its specific quality. From the viewpoint of Habermas’ concept of deliberative democracy (1987) we define that only political discussion, which is oriented towards communicative principles of understanding, can promote the development of a deliberative public sphere. Along a “quality index of understanding” we examine political parties and candidates’ Facebook communication (N = 9428 posts and comments) during the most recent Austrian elections in Vienna in October 2010. The political discussion is following the principles of a “quality of understanding” if political actors do not only state their positions, but also give statements of reasons. If, in the case of debatable questions, they present specific proposals for solutions, they deal with others in a more or less respectful way and they express relevant doubts concerning positions and other participants.
