The rise of sound bite news is one of the best-established findings in political communication research. It is also one of the most widely deplored. Yet there is little empirical knowledge about the substantive costs actually associated with sound bite journalism. This study proposes that a particularly important and likely consequence of shrinking sound bites on television news is the emergence of incomplete argument, in which speakers presenting their opinion on a political issue are less likely to also justify it. Using multilevel analyses of data from probabilistic samples of television news in three types of formal democracies (Germany, Russia, and the United States) the study shows that (1) shrinking sound bites have a significant negative effect on the probability of opinion justification and that this effect is robust across national contexts; it shows that (2) this effect is generally more pronounced for non-journalist speakers than journalists speaking on the news, and illustrates (3) a substantial decline in the predicted marginal probabilities of opinion justification in German and U.S. television news during the last decades. Taken together, sound bite journalism emerges as antithetical to television news’ ability to produce public justification.
