Pragmatic Persuasion: How Communicative Processes Make Information Appear Persuasive
There are many ways to change attitudes, as this book attests, and many involve presenting arguments (e.g., Crano, this volume; Prislin, this volume). Consequently, the impact of arguments has gured prominently in the history of attitude research where the characteristics of persuasive messages (Hovland, Janis, & Kelley, 1953) and the processes by which they affect attitudes (Chen & Chaiken, 1999; Greenwald, 1968; Kruglanski, Thompson, & Spiegel, 1999; Petty & Wegener, 1999) have been investigated (for reviews, see Bohner & Wänke, 2002; Crano & Prislin, 2006). That a convincing argument comes in handy when attempting to change attitudes is, of course, common knowledge and is practiced widely in social interaction, education, politics, marketing, and other areas. But what is a convincing argument? In logic, an argument is a set of premises and a conclusion, with the characteristic that the truth of the conclusion is supported by the premises. “You should eat vegetables (conclusion) because they contain lots of vitamins (premise)” sounds like a reasonable argument to most people, whereas “you should eat vegetables because they are green” does not. The intake of vitamins is considered benecial by most people but the benet of eating green food is less obvious. But note, that it is not the information per se which is convincing or not, but-as always in social psychology-what receivers make of it. For information to change a person’s attitude in the desired direction, it is essential that the receiver draws the adequate inferences about its implications. The argument that vegetables contain vitamins will be lost on ignorant recipients who do not know what vitamins are. Thus, one may dene information as compelling if, given the recipient’s knowledge structure, this information leads the recipient to the conclusions desired by the persuader.