Intelligent life may be inconceivably rare
The case was made that despite a vast number of planets, the fact that we only have one confirmed data point (Earth) suggests intelligent life could be 'inconceivably rare' rather than common.
Keep reading this one
You've read the thesis and who argued it. A free account opens the argument, what validates it, the risks the show raised, and the moment in the episode where it was said — 3 ideas in full a day, no card.