Destructive or Deliberative? An Investigation of the Evolution, Determinants, and Effects of the Quality of Political Debate

In recent years, concerns have been raised repeatedly about the poor quality of the political debate. Particularly the uncivil and ill-justified ways in which politicians regularly seem to express their views and standpoints raise scholarly and public concern (e.g. Dryzek et al., 2019). Yet despite severe concerns, surprisingly often statements such as "we are currently living in an era of incivility" or "soundbite culture" are based on anecdotes and assumptions rather than systematically driven research. This dissertation contributes to filling this gap and specifically advances our knowledge of the evolution, the determinants, and the effects of politicians' use of uncivil (i.e. disrespectful) and ill-justified (i.e. poorly reasoned) arguments in mediated political debates. Accordingly, three research questions guide this dissertation: (1) Did politicians' use of incivility and ill-justified arguments increase over time (1985-2019)?; (2) Which determinants influence politicians' use of incivility and ill-justified arguments? For instance, how do populism, media characteristics and country-specific characteristics influence it?; and (3) How are citizens' attitudes, specifically their trust attitudes towards politics and towards the news media, affected by incivility and ill-justified arguments? By studying these questions in the western European context, novel insights are brought to the predominantly U.S.-focused literature on mediated debate quality. To address these three questions, I connect the field of political communication to the theory of deliberative democracy. Within deliberative democratic theory, civility and well-justified arguments are two of the key ideals that define a high-quality political debate (e.g. Bächtiger et al., 2018; Wessler, 2008). These normative ideals can therefore serve as conceptual and methodological benchmarks to investigate causes and consequences of deviations from it (Steiner et al., 2004). Hence, I innovatively use the deliberative benchmark as a systematic, empirical tool to study (1) to what degree politicians deviate from this benchmark over time; (2) which determinants influence deviations from this benchmark; (3) how deviations from this benchmark influence citizens' trust attitudes. Furthermore, I study these questions in the venue of political debates in the media (e.g. televised election debates). The deliberative quality of political debates is largely underexplored in mediated debate venues (as compared