An Observational Analysis of Argument Structures: The Case of Nightline BRENT G. BROSSMANN AND DANIEL J. CANARY Department of Speech Communication California State University, Fullerton Fullerton, CA 92634 U.S.A. ABSTRACT: An observational analysis of selected Nightline program transcripts was undertaken to advance understanding of conversational arguments used in the service of public policy debate. Results indicate that Nightline discussions involved more compound structural variations, but fewer simple, convergent and eroded argument structures than had been found in previous research. In contrast to previous efforts, the development of prompter and delimitor argument structures was also identified. In addition, the program's moderator, Ted Koppel, used challenge structures as his primary method of proposing issues for debate. Discussion focuses on features of Nightline argument complexity and proposes directions for future research. KEY WORDS: Simple arguments, compound arguments, convergent arguments, eroded arguments, convergence markers, arguables, prompters, delimitors, non-arguables. Initial attempts to examine arguments beyond traditional public speaking contexts are now more than a decade old. Brockriede's (1975) search for argument and O'Keefe's (1977, 1982) distinction between making and having arguments pointed to "new" argumentation research, research that quickly focused on everyday interaction. The inclusion of ordinary discourse research has linked argumentation "more closely to the broader speech communication discipline" (Cox & Willard, 1982). Evidence of the embrace of argumentation research to everyday interaction contexts is witnessed in dozens of recent studies (see Meyers & Seibold, 1987; Trapp, Hoff, & Chandler, 1987; for reviews) and over fifty articles on conversational argument published in the Alta conference summer pro- ceedings (Cox, Sillars, & Walker, 1985; Wenzel, 1987; Zarefsky, Sillars, & Rhodes, 1983; Ziegelmueller & Rhodes, 1981). However, surprisingly little research has examined the nature of conversational arguments used to guide public awareness of social issues and policies. Of particular interest here is how conversational arguments are used on television programs. Although many television programs lend themselves to observational analyses of message exchanges, the ABC late night news show Nightline is Argumentation 4: 199-212, 1990. C 1990 KluwerAcademic Publishers. Printed in the Netherlands.