Where's Darth Vader?
Smith countered with The Fermi Paradox. If alien civilizations all around us some would be smart enough to travel faster than light and they'd be here by now. So, if aliens exist at all, they are not that clever. Nor have they been able to come and conquer us, which would have a statistical probability in a universe teeming infinite worlds. There's gotta be at least one Darth Vader out there somewhere.
The esteemed Harvard science historian, Owen Gingerich, dismissed this debate by simply saying, "We cannot extrapolate from just one example of intelligent life."
Nevertheless, this dialogue leaves me as optimistic as ever of finding E.T. In fact I would say it is a 50/50 bet that SETI tells us that "we are not alone" before the great space observatories needed for conclusively finding Earth II are ever built. That is, assuming aliens uses radio or optical transmissions for saying "hi."
But what would happen next?