"Those who have knowledge, don’t predict. Those who predict, don’t have knowledge.” Lao Tzu
This famous quote was uttered over 2500 years ago and may strike some people as odd that, as a 
professional futurist, I have chosen to highlight it.
My rationale is two-fold. First, as I have said many times before, the chief responsibility of a futurist is not to “predict” the future but rather outline a range of future possibilities. Second, and more important, I have highlighted the quote because it is true.
If you have not already read Nassim Taleb's outstanding book, The Black Swan: The Impact of the Highly Improbable, do so as soon as possible. On Page 177 of the book, Taleb has an illustration of the scattering effect which artfully explains why predicting the future—especially for longer time frames—is virtually impossible.
Because I can’t reprint the figure here, I am left with Taleb’s analogy for understanding the scattering effect: the prediction of a billiard ball.
Assuming one has knowledge of the location of every ball and the speed and accuracy of the cue ball, it is relatively easy to predict the movement of the ball after the first shot. A person might even expect that, due to the growing computational power of computers, the second, third and fourth degree movements can be estimated with great accuracy. The problem, however, grows increasingly complex with each subsequent movement and after the ninth movement the gravitational pull of a person standing at the next pool table exerts enough of an effect to alter the trajectory of the ball. And after 56 movements even the smallest particle on the outer edge of the universe will effect the trajectory!
The bottom line is this: There are simply too many factors to consider when contemplating the future 20, 30, 50 or 100 years out. (Even a small effect today can have outsized implications 50 years hence). The situation, of course, becomes even more complicated because of Taleb’s main thesis which is that “Black Swans”—described as “high impact, low probability” events—tend to shape the future more than “expected” trends.
Therefore, whether a future “Black Swan” takes the shape of a pandemic, an asteroid, an E-bomb, a rogue terrorist attack, a North Korean or Iranian nuclear attack, an unexpected breakthrough in quantum computing or synthetic biology, or, more likely, some “unknown unknown;” the future will be difficult too predict because we don’t have—and won’t ever have—enough knowledge about the future.
