>Rosling’s “Factfulness” starts with a quiz of 12 questions—ranging from “How many children will there be in 2100?” to “In the last 20 years, the proportion of

>Rosling’s “Factfulness” starts with a quiz of 12 questions—ranging from “How many children will there be in 2100?” to “In the last 20 years, the proportion of the world population living in extreme poverty has almost doubled, stabilized or reduced by half?”—to which he then applies his “chimpanzee test”—the likelihood that a random choice is superior to that of humans. Humans always seem to fail the test: even CEOs at the World Economic Forum. That question about the number of children in 2100 really bothers me for some reason. Sure we can make some pretty reasonable projections, but they will be just that: projections. Even assuming no black swan events, the error bars 80 years from now have got to be enormous. The numbers could be wildly different depending on how bad climate change turns out, and what kinds of technologies we develop. If you're trying to prove that other people are overly pessimistic, it makes more sense to show that they are wrong about currently available data. Otherwise they can just say that your answer to the question is overly optimistic.