# Generalizing from One Trend

**Related:** [Reference Class of the Unclassreferenceable](/lw/1lx/reference_class_of_the_unclassreferenceable/ ), [Generalizing From One Example](/lw/dr/generalizing_from_one_example/)

Many people try to predict the future. Few succeed.

One common mistake made in predicting the future is to simply take a current trend and extrapolate it forward, as if it was the only thing that mattered-- think, for instance, of the future described by cyberpunk fiction, with sinister (and often Japanese) multinational corporations ruling the world. Where does this vision of the future stem from?

Bad or lazy predictions from the 1980s, when sinister multinational corporations (and often Japanese ones) looked to be taking over the world.^\[1\]^

Similar errors have been committed by writers throughout history. George Orwell thought _1984_ was an accurate prediction of the future, seeing World War II as inevitably bringing socialist revolution to the United Kingdom and predicting that the revolutionary ideals would then be betrayed in England as they were in Russia.  Aldous Huxley agreed with Orwell but thought that the advent of hypnosis and psychoconditioning would cause the dystopia portrayed in _1984_ to evolve into that he described in _Brave New World._ In today's high school English classes, these books are taught as literature, as well-written stories-- the fact that the authors [took their ideas seriously](/lw/2l6/taking_ideas_seriously/) would come as a surprise to many high school students, and their predictions would look laughably wrong.

Were such mistakes confined solely to the realm of fiction, they would perhaps be considered amusing errors at best, reflective of the sorts of mishaps that befall unstudied predictions. Unfortunately, they are not. Purported "experts" make just the same sort of error regularly, and failed predictions of this sort often have negative consequences in reality.

For instance, in 1999 two economists published the book _[Dow 36,000](http://en.wikipedia.org/wiki/Dow_36,000),_ predicting that stocks were about to reach record levels; the authors of the book were so wrapped up in recent gains to the stock market that they assumed that such gains were in fact the new normal state of affairs, that the market hadn't corrected for this yet, and that once stocks were correctly perceived as safe investments the market would skyrocket. This not only did not happen, but the dot-com bubble burst shortly after the book was published.^\[2\]^ Anyone following the market advice from this book lost big.  

In 1968, the biologist Paul R. Ehrlich, seeing disturbing trends in world population growth, wrote a book called _The Population Bomb,_ in which he forecast (among other things) that "The battle to feed all of humanity is over. In the 1970s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now." Later, Ehrlich doubled down on this prediction with claims such as  "By the year 2000 the United Kingdom will be simply a small group of impoverished islands, inhabited by some 70 million hungry people ... If I were a gambler, I would take even money that England will not exist in the year 2000."

Based on these predictions, Ehrlich advocated cutting off food aid to India and Egypt in favor of preserving food supplies for nations that were not "lost causes;" luckily, his policies were not adopted, as they would have resulted in mass starvation in the countries suddenly deprived of aid. Instead, food aid continued, and as population grew, food production did as well. Contrary to the increase in starvation and global death rates predicted by Ehrlich, global death rates decreased, the population increased by more than Ehrlich had predicted would lead to disaster, and the average amount of calories consumed per person increased as well.^\[3\]^

So what, then, is the weakness that causes these analysts to make such errors?

Well, just as you can [generalize from one example](/lw/dr/generalizing_from_one_example/) when evaluating others and hence fail to understand those around you, you can generalize from one trend or set of trends when making predictions and hence fail to understand the broader world. This is a special case of the classic problem where "to a man with a hammer, everything looks like a nail;" if you are very familiar with one trend, and that's all you take into account with your future forecasts, you're bound to be wrong if that trend ends up _not_ eating the world.

On the other hand, the trend sometimes _does_ eat the world. It's very easy to find long lists of buffoonish predictions where someone woefully understimated the impact of a new technology.^\[4\] ^Further, determining exactly when and where a trend is going to stop is quite difficult, and most people are incompetent at it, even at a professional level-- if this were easy, the stock market would look extraordinarily different!  

So my advice to those who would predict the future is simple. Don't generalize from one trend or even one group of trends. Especially beware of viewing evidence that seems to support your predictions as evidence that other people's predictions must be wrong-- [the notebook of rationality](/lw/h1/the_scales_of_justice_the_notebook_of_rationality) [cares not for what "side" things are on](/lw/gt/a_fable_of_science_and_politics/), but rather for [what is true](http://wiki.lesswrong.com/wiki/Truth). Even if the trend you're relying on does end up being the "next big thing," the rest of the world will have a voice as well.^\[5\]^

  

\[1\] I predict that the work of [Cory Doctorow](http://en.wikipedia.org/wiki/Cory_Doctorow) and those like him will seem similarly dated a decade down the line, as the trends they're riding die down. If you're reading this during or after December 2022, please let me know what you think of this prediction.

\[2\] The authors are, of course, still employed in cushy think-tank positions.

\[3\]  Ehrlich has doubled down on his statements, now claiming that he was "way too optimistic" in _The Population Bomb_ and that the world is obviously doomed.

\[4\] I personally enjoy the [Bad Opinion Generator](http://theweek.com/home/bad_opinions) (warning: potentially addictive)

\[5\] Technically, this [isn't always true](/). But you should assume it is unless you have _extremely_ good reasons to believe otherwise, and even still I would be very careful before assuming that your thing is _the_ thing.