ABSTRACT
In a story written by Rex Stout in 1949 called “Instead of Evidence”, a man is killed by an explosive hidden in a cigar he smokes. When the police examine the cigar box, they find that several of the cigars have been carefully and skilfully rewrapped with explosive hidden inside them. When all of the cigars are taken out of the box, they discover a few strands of long hair. Inspector Cramer suspects that the man’s wife, Martha, is the killer. He believes that if Martha’s hair is in the box then she’s the murderer. And he tells the heroes of the novel, Nero Wolfe and Archie Goodwin, that it is Martha’s hair. Inspector Cramer concludes that Martha is the murderer and he wants to arrest her. However, Martha is Nero Wolfe and Archie Goodwin’s client. They believe she is not the murderer. Such contradictions are common, not only in fiction but also in real life. A theory predicts a certain observation, but the data reveal otherwise; an economic policy dictates a certain course of action, but the politicians responsible for implementing it take a different course; your memory for where you left your keys indicates they should be in their usual place, but when you look for them, they’re not. One of Paolo Legrenzi’s most recent important contributions to our knowledge about human reasoning has been to show that people can detect some inconsistencies readily (Legrenzi, Girotto, & Johnson-Laird, 2003) and our interest in this chapter is in how people resolve such contradictions.
