This. I have never found the 'paradox' convincing for exactly this reason. The presumptive extrapolation in its formalization is breathtaking. It is primarily

This. I have never found the 'paradox' convincing for exactly this reason. The presumptive extrapolation in its formalization is breathtaking. It is primarily useful IMO for posing an estimate to answer a different question from the one people believe it does, which is simply, 'what is the incidence of life, much as we know it...?' ...where 'as we know it' is extremely narrow and rests upon the equally narrow 'physics as we know it.' We are smart monkeys, but while we have learned a breathtaking amount in the last couple centuries, our overconfidence in what we think we know remains constant. You can hold most of the assumptions constant and still come up with many reasons for the 'silence' of the skies, none of which reflect upon the incidence of intelligent life or advanced civilization... :P