From Everything Is Obvious: How Common Sense Fails Us:
So powerful is the appeal of a good story that even when we are trying to evaluate an explanation scientifically—that is, on the basis of how well it accounts for the data—we can’t help judging it in terms of its narrative attributes. In a range of experiments, for example, psychologists have found that simpler explanations are judged more likely to be true than complex explanations, not because simpler explanations actually explain more, but rather just because they are simpler. In one study, for example, when faced with a choice of explanations for a fictitious set of medical symptoms, a majority of respondents chose an explanation involving only one disease over an alternative explanation involving two diseases, even when the combination of the two diseases was statistically twice as likely as the single-disease explanation. Somewhat paradoxically, explanations are also judged to be more likely to be true when they have informative details added, even when the extra details are irrelevant or actually make the explanation less likely.