An excerpt from Duncan Watts, Everything Is Obvious: when you know the answer* (2012, chapter 3)
Although it is rarely presented as such, this kind of circular reasoning—X succeeded because X had the attributes of X—pervades commonsense explanations for why some things succeed and others fail. For example, an article on the success of the Harry Potter books explained it this way:
“A Cinderella plot set in a novel type of boarding school peopled by jolly pupils already has a lot going for it. Add in some easy stereotypes illustrating meanness, gluttony, envy, or black-hearted evil to raise the tension, round off with a sound, unchallenging moral statement about the value of courage, friendship, and the power of love, and there already are some of the important ingredients necessary for a match-winning formula.”
In other words, Harry Potter was successful because it had exactly the attributes of Harry Potter, and not something else.
Likewise, when Facebook first became popular, conventional wisdom held that its success lay in its exclusivity to college students. Yet by 2009, long after Facebook had opened itself to everyone, a report by Nielsen, the ratings company, attributed its success to its broad appeal, along with its “simple design” and “focus on connecting.” Facebook, in other words, was successful because it had exactly the attributes of Facebook, even as the attributes themselves changed completely. Or consider a news story reviewing 2009 movies that inferred from the success of The Hangover that “relatable, non-thinking comedies … are the perfect balm for the recession,” implying in effect that The Hangover succeeded because moviegoers wanted to see a movie like The Hangover, and not something else. In all these cases, we want to believe that X succeeded because it had just the right attributes, but the only attributes we know about are the attributes that X possesses; thus we conclude that these attributes must have been responsible for X’s success.
Even when we are not explaining success, we still rely on circular reasoning to make sense of why certain things happen. For example, in another recent news story about an apparent downshift in postrecession consumer behavior, one expert explained the change with the helpful observation that “It’s simply less fun pulling up to the stoplight in a Hummer than it used to be. It’s a change in norms.” People do X, in other words, because X is the norm, and it is normal to follow norms. OK, great, but how do we know that something is a norm? We know because people are following it. And this is no isolated example. Once you start to pay attention, it’s amazing how often explanations contain this circularity. Whether it is women getting the vote, gay and lesbian couples being allowed to marry, or a black man being elected president, we routinely explain social trends in terms of what society “is ready for.” But the only way we know society is ready for something is because it happened. Thus, in effect, all we are really saying is that “X happened because that’s what people wanted; and we know that X is what they wanted because X is what happened.”