Instapundit runs a lengthy excerpt on Matt Ridley's article on pessimists.
Rest the whole thing, of course, but what keeps the pessimists going? Like terrorists, they only have to be right once.
We can foil terrorists thousands of times, put many in jail, and they can still claim success with one bombing or other attack.
If you claim the world is going to fall apart, eventually you will be right. As long as we don't fight to keep it together.