One thing I like to bring to these debates is the idea that people, in general, are really bad at understanding probabilities at the scale that is required here

One thing I like to bring to these debates is the idea that people, in general, are really bad at understanding probabilities at the scale that is required here. And I'm not talking about probabilities that deal with how large the universe is. We know that it is unfathomably huge, with countless galaxies, stars, and planets. But in "Fermi's Pair o' Decks" there is an illustration of just how few things need to align "just so" to make it almost certain that we are the only life in the universe: https://shaungallagher.pressbin.com/blog/aliens.html https://shaungallagher.pressbin.com/blog/aliens.html In fact, all you need are two decks of playing cards to understand how combinatorics can very quickly overwhelm our intuitions.