Interestingly from the population statistics alone it is possible to make an argument about the total likely future number of humans that will live. There is debate about whether the reasoning is correct, but it is at least suggestive. See http://en.wikipedia.org/wiki/Doomsday_argument for more.
I don't think the Doomsday Argument is that interesting. It may be trivially true, but it doesn't tell us anything interesting or predictive. All it says is that the chronology of human existence is too complicated for us to calculate. That being the case, our working assumption can only be that we're at the midpoint of our species population line. But, keep in mind that this estimate is really, really horrible, it's only virtue being that it's better than all the others.
If someone gave you a trick coin, and you didn't know which side was favored, you'd have to assume 50/50, even knowing that you were certainly wrong. Knowing that one side is weighted doesn't give you any interesting information for one toss.
If you follow the arguments for and against the DA, it's clear this isn't about a well-defined statistical argument, but immediately devolves into qualitative arguments about our survivability. The optimists say, well, based on the average extinction rate it's extremely unlikely we'll die in <100 million years. The pessimists counter that we're creating technologies with extinction level capacities very rapidly. Either way, we don't have a way of gauging the predictive power of these claims. We can't run a controlled study of 100 human species spans.
And that's fine, because we need to argue about and introspect on the longevity of species, but brainteasers like the DA don't further it in any meaningful way.
I don't think the Doomsday Argument is that interesting. It may be trivially true, but it doesn't tell us anything interesting or predictive.
If it is true, it can let us put probabilistic upper bounds on the future of the human race. For instance with 99.99999% likelihood I can tell you that the human race will fail to succeed in expanding colonization of other stars. As much as we may dream of the stars, we will never reach them.
Similarly the odds of our maintaining our current population levels for the next thousand years is something like 40%. That is both interesting and predictive. Its meaning, however, is highly debatable.
I am familiar with the arguments suggesting that population growth is self-limiting. I am also aware that the spread of birth control is breeding people whose will fail to use it. They may be a small portion of the overall population, but any portion that is on an exponential curve when the rest are not is bound to eventually dominate the population.
Malthus has been postponed for centuries. And may well be postponed for more centuries. But unless resources grow exponentially, Malthus eventually will have the last laugh.
Scared? I remember distinctly the book ended with a "cautious optimism".
Yes, it points out a lot of potential problems, and makes it obvious that societies _do_ fail, and that we're not yet above that rule, but I wouldn't call it scary.
Interestingly from the population statistics alone it is possible to make an argument about the total likely future number of humans that will live. There is debate about whether the reasoning is correct, but it is at least suggestive. See http://en.wikipedia.org/wiki/Doomsday_argument for more.