Biases and fallacies

This paper focuses on the effects of motivational biases on the way people reason and debate in everyday life. Unlike heuristics and cognitive biases, motivational biases are typically caused by the influence of a desire or an emotion on the cognitive processes involved in judgmental and inferential reasoning. In line with the ‘motivational’ account of irrationality, I argue that these biases are the cause of a number of fallacies that ordinary arguers commit unintentionally, particularly when the commitment to a given viewpoint is very strong. Drawing on recent work in argumentation theory and psychology, I show that there are privileged links between specific types of biases and specific types of fallacies. This analysis provides further support to the idea that people’s tendency to arrive at desired conclusions hinges on their ability to construct plausible justifications for those conclusions. I suggest that this effort to rationalize biased views is the reason why unintentional fallacies tend to be persuasive.