If all I knew was that there were going to be a finite number of humans and I was one of them then I'd have to say that there's a 90% chance that I'm in the last 90%. But I have made other observations. As stated in the problem, I know that the population is increasing geometrically. With the possibility of truly vast numbers of new people being added, how is it possible for anyone to seriously think that he's now probably in the last 90%?

It would be different if the earth really had standing room only or a killer asteroid were already spotted. But as it is, the same geometric progression that suggests that most of the people who will ever live will be in the last few generations also suggests that we aren't in those generations.

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Life is like a box of chocolates. All of your choices are bad for you.