I don't know about that. Even if we're talking about a large sample size, can we really say "that probability is vanishingly small"? It's kind of like saying, "

I don't know about that. Even if we're talking about a large sample size, can we really say "that probability is vanishingly small"? It's kind of like saying, "Sure, I don't see any reason why someone would build an underwater city, but with a couple hundred countries in the world, and 7 billion people, the probability that no one is going to do that is tiny." But are we even dealing with a large sample size? Maybe there's "only" been several dozen large interstellar civilizations out there, and a few hundred small ones that never really got far beyond a handful of planets. Or maybe there were a couple of attempts, but they failed horribly. The problem with the "paradox" is that there seems to be a huge number of possible answers. It ends up being "how come this one scenario I'm thinking about hasn't happened."