The Elephant in the Brain: Hidden Motives in Everyday Life

by Kevin Simler

Puzzle 3: The Criterion of Relevance According to the reciprocal-exchange theory, conversations should be free to bounce around willy-nilly, as speakers take turns sharing new, unrelated information with each other. A typical conversation might go something like this: A: FYI, Alex and Jennifer are finally engaged. B: Thanks. Have you heard that the President is trying to pass a new healthcare bill? A: Yeah, I already knew that. B: Oh. In that case, um . . . a new Greek restaurant just opened on University Avenue. A: That’s new information to me. Thanks. Either listener might ask follow-up questions, of course. But as soon as their curiosity had been satisfied, they might be expected to turn around and share some new information of their own, regardless of whether it pertained to the previous discussion. But this is not what human conversation looks like. Instead we find that speakers are tightly constrained by the criterion of relevance.19 In general, whatever we say needs to relate to the topic or task at hand. Conversations can meander, of course, but the ideal is to meander gracefully. Speakers who change the topic too frequently or too abruptly are considered rude, even if they’re providing useful information.