Guided by argumentation schema theory, we conducted five psychological studies in the United States and China on arguments about vaccination. Study 1 replicated research about arguments on several topics, finding that agreement judgments are weighted toward claims, whereas quality judgments are weighted toward reasons. However, consistent with recent research, when this paradigm was extended to arguments about vaccination (Study 2), claims received more weight than reasons in judgments about agreement and quality. Studies 3 and 4 were conducted in the United States and China on how people process counterarguments against anti-vaccination assertions. Rebuttals did not influence agreement but played a role in argument quality judgments. Both political position (in the United States) and medical education (in China) predicted differences in argument evaluation. Bad reasons lowered agreement (Study 5), especially among participants studying health care. Political polarization apparently heightens the impact of claim side in the argumentation schema, likely to the detriment of public discourse.

Argumentation schema theory guided four experiments on the processing of plausible and implausible reasons and warrant statements testing the hypothesis that most reasons produce greater agreement with claims than when claims are presented without support. Another hypothesis was that leaving warrants unstated often produces greater agreement than when the warrant is made explicit. In Study 1, American participants were more likely to agree with claims after they read arguments than beforehand—even those with implausible reasons and warrants. In Study 2, American history and environmental science majors read brief arguments and agreed more with implausible arguments than claims alone. Study 3, with Chinese participants, replicated some but not all earlier results. In Study 4, with Chinese participants, blatantly false claims supported by bogus reasons yielded marginally greater agreement than unsupported claims. These findings suggest that many people have uncritical argumentation schemata with low support thresholds, making them vulnerable to weak and bogus arguments.

Three studies examined the “myside bias” in reasoning, evaluating written arguments, and writing argumentative essays. Previous research suggests that some people possess a fact-based argumentation schema and some people have a balanced argumentation schema. I developed reliable Likert scale instruments (1-7 rating) for these constructs and conducted an evaluation of instrument validity and reliability. A myside bias in argumentative essays was predicted by the fact-based and balanced argumentation schema instruments using these individual-difference measures. Strength of opinion predicted the myside bias in generating reasons but not in writing argumentative essays. There was a weak but significant correlation between the myside bias in generating reasons and writing argumentative essays. In evaluating written arguments, the fact-based schema instrument predicted agreement and quality ratings for claims supported by factual but not nonfactual reasons. Ratings of the quality of rebutted arguments were predicted by the measures of individual differences in argumentation schemata.

This study explores how different kinds of arguments are situated in academic contexts and provides an analysis of undergraduate writing assignments. Assignments were collected from the schools of business, education, engineering, fine arts, and interdisciplinary studies as well as the humanities, natural sciences, and social sciences in the College of Arts and Science. A total of 265 undergraduate writing assignments from 71 courses were analyzed. Assignments were reliably categorized into these major categories of argumentative writing: explicitly thesis-driven assignments, text analysis, empirical arguments, decision-based arguments, proposals, short answer arguments, and compound arguments. A majority of writing assignments (59%) required argumentation. All engineering writing assignments required argumentation, as did 90% in fine arts, 80% of interdisciplinary assignments, 72% of social science assignments, 60% of education assignments, 53% in natural science, 47% in the humanities, and 46% in business. Argumentation is valued across the curriculum, yet different academic contexts require different forms of argumentation.

This article describes a cognitive argumentation schema for written arguments and presents three empirical studies on the “myside” bias—the tendency to ignore or exclude evidence against one's position. Study 1 examined the consequences of conceding, rebutting, and denying other-side information. Rebuttal led to higher ratings of agreement and quality and better impressions of the author than when the same arguments excluded other-side information (i.e., exhibited the myside bias). In Study 2, claims had a significantly greater impact on agreement ratings and reasons had a significantly greater impact on quality ratings. When participants were given myside reasons supporting other-side claims, they acknowledged argument strength while making relatively minor changes in agreement. In Study 3, the authors found that a brief, theoretically motivated written tutorial was effective in improving undergraduate students' written argumentative essays by significantly increasing the precision of claims, improving the elaboration of reasons, and reducing the myside bias.

The article explores the rhetorical dimensions of witnessing. We concentrate, in particular, on two groups: 1) university students at the University of San Carlos, Quetzaltenango, whose murals are dramatic reminders of the massacres that resulted in the deaths of over 200,000 indigenous people in the 1980s and early 90s and of the corrupt governmental leaders responsible for them, and 2) U.S. accompaniers sponsored by an organization within our own community, the Copper Country Guatemala Accompaniment Project (CCGAP).