The most pressing threat to civilization is us -- and paradoxically, we’re also the solution. When Paul Ehrlich published “The Population Bomb” in 1968, he ushered in an era of doomsday predictions that we’re still in. There are more than twice as many people in the world now than when his book came out, and Ehrlich insists that the population bomb just hasn’t gone off yet. But optimists like Julian Simon see something else happening. They acknowledge that man-made threats of destruction are not only challenges we can solve -- and that we’re in a better position every day to eliminate our problems -- but that we’re also better off for it.