I have shelves of books and papers by smart people who have brushed up against the edge of this question but who have seldom attacked it head on. I'm drawn to the question, and have been obsessed with it for years, because I think it's one of the big ones. It touches on everything humans do.
Fashions and fads are everywhere; in things as diverse as food, furnishings, clothes, flowers, children's names, haircuts, body image, even disease symptoms and surgical operations. Apparently, even the way we see Nature and frame questions about it is affected to some extent by fashion; at least according to those who would like to throw cold water on somebody else's theory. (In the current discussion, Paul Davies says, "Of late, it is fashionable among leading physicists and cosmologists to suppose that alongside the physical world we see lies a stupendous array of alternative realitiesŠ")
But the ubiquity of fads has not led to deep understanding, even though there are serious uses to which a working knowledge of fads could be put. A million children each year die of dehydration, often where rehydration remedies are available. What if rehydration became fashionable among those children's mothers? Public health officials have many times tried to make various behaviors fashionable. In promoting the use of condoms in the Philippines or encouraging girls in Africa to remain in school, they've reached for popular songs and comic books to deliver the message, hoping to achieve some kind of liftoff. Success has been real, but too often temporary or sporadic. Would a richer understanding of fads have helped them create better ones?
In trying to understand these phenomena, writers have been engaged in a conversation that has spanned more than a hundred years. In 1895 Gustave LeBon's speculations on "The Crowd" contained some cockeyed notions, and some that are still in use today. Ludwik Fleck, writing on "The Evolution of a Scientific Fact" in the thirties, in part inspired Thomas Kuhn's writings on the structure of scientific revolutions in the sixties. Everrett Rogers's books on the "Diffusion of Innovations" led to hundreds of other books on the subject and made terms like early adopters and agents of change part of the language. For several decades positive social change has been attempted through a practice called Social Marketing, derived in part from advertising techniques. Diffusion and social marketing models have been used extensively in philanthropy, often with success. But to my knowledge these techniques have not yet led to a description of the fad that's detailed and testable.
Malcom Gladwell was stimulating in identifying elements of the fad in The Tipping Point but we are still left with a recipe that calls for a pinch of this and a bit, but not too much, of that.
Richard Dawkins made a dazzling frontal assault on the question when he introduced the idea of memes in The Selfish Gene. The few pages he devoted to the idea have inspired a number of books and articles in which the meme is considered to be a basic building block of social change, including fads. But as far as I can tell, the meme is still a fascinating idea that urges us toward experiments that are yet to be done.
Whether memes or some other formulation turns out to be the engine of fads, the process seems to go like this: a signal of some kind produces a response that in turn acts as a signal to the next person, with the human propensity for imitation possibly playing a role. This process of signal-response-signal might then spread with growing momentum, looking something like biological contagion. But other factors may also apply, as in Steve Strogatz's examination of how things sync up with one another. Or Duncan Watt's exploration of how networks of all kinds follow certain rules of efficiency. Or the way crowds panic in a football stadium or a riot. Or possibly even the studies on the way traffic flows, including the backward generated waves that cause mysterious jams. The patterns of propagation may turn out to be more interesting than anything else.
Fads and fashions have not been taken very seriously, I think, for at least three reasons. They seem short-lived, they're often silly and they seem like a break with normal, rational behavior. But as for being short-lived, the history of fads gives plenty of examples of fads that died out only to come back again and again, eventually becoming customary, including the use of coffee, tomatoes and hot chocolate. As for silliness, some fashions are not as silly as they seem. Fashions having to do with the length of one's hair seem trivial; yet political and religious movements have often relied on the prominence or absence of hair as a rallying symbol. And fads are far from aberrational. There are probably very few people alive who, at any one time, are not under the sway of a fad or fashion, if not dozens of them. And this is not necessarily a vacation from rational behavior on our part. On the contrary, it might be essential to the way we maximize the effectiveness of our choices. Two economists in California have developed a mathematical model suggesting that in following the lead of others we may be making use of other people's experience in a way that gives us a slightly higher chance of success in adopting a new product. The economists say this may explain a burst of popularity in a new product and possibly throw light on fads themselves.
But another reason fads may not have been examined in more detail, and this could be the killer, is that at least for the moment they just seem too complicated. Trying to figure out how to track and explain change is one of the oldest and toughest of questions. Explaining change among people in groups is perhaps complex beyond measure, and may turn out to be undoable. It may forever be an art and not a science. But still, the humble fad is too tantalizing to ignore.
We take it for granted and dismiss it, even while we're in the rapture of it. This commonplace thing that sits there like the purloined letter may or may not turn out to contain a valuable message for us, but it is staring us in the face.