Economists are often lambasted for making predictions. Or at the very least, they are often lambasted for making predictions that history singled out as being particularly wrong. The most infamous was provided by British economist John Maynard Keynes in Economic Possibilities for our Grandchildrenwhere he opined that, by 2030, the average work week would be around 15 hours (3 hours per work day). Essentially, this was a prediction about how much productivity growth there would be and how it would allow us to consume a great deal with very little effort. We are far away from that prediction: the average British worker worked 45 hours a week circa 1930 as opposed to 32 hours today. Thus, it is easy to see how we could lambast Keynes for being spectacularly wrong.
However, Keynes was right and those who have lambasted him are wrong because they fail to appreciate the role of gains in life expectancy.