That Wikipedia article (which is a pretty good one) puts the problem that Fermi perceived this way: “The apparent size and age of the universe suggest that many technologically advanced extraterrestrial civilizations ought to exist. However, this hypothesis seems inconsistent with the lack of observational evidence to support it.” But we have no telescopes powerful enough to see what might be happening on any of the small number of exoplanets that have been directly observed. So there’s no “observational evidence” one way or the other.
Unless, of course, we mean alien civilizations that might be observed right here on earth.
|From the movie Signs|
That’s where this way of formulating the problem comes in (again from the Wikipedia article): “Given intelligent life's ability to overcome scarcity, and its tendency to colonize new habitats, it seems likely that at least some civilizations would be technologically advanced, seek out new resources in space and then colonize first their own star system and subsequently the surrounding star systems.” Does “intelligent life” really have a “tendency to colonize new habitats”? Wouldn't it be more accurate to say simply that some human societies have this tendency?
The assumptions here are, it seems to me, pretty obvious and pretty crude: that the more intelligent “intelligent life” becomes, the more likely it will be to have an expansionary, colonizing impulse. In other words, superior alien civilizations will be to us as Victorian explorers were to the tribes of Darkest Africa. Higher intelligence is then identified with (if we’re inclined to be critical) the British Empire at its self-confident apogee or (if we’re inclined to be really critical) the Soviet Union or Nazi Germany in their pomp. (It’s all about the galactic Lebensraum, baby!)
But I see no reason whatsoever to grant this assumption. Why would the drive to become a “hegemonising swarm” — as Iain M. Banks refers to this kind of society in his Culture novels — be a mark of high intelligence? Though the Culture itself has strong hegemonizing tendencies, which it tries with partial success to keep under control, the most sophisticated societies in those books are the ones who have chosen to “sublime”, that is, opt out of ordinary space/time altogether.
Perhaps the impulse to colonize is, or could be, merely a stage in the development of intelligence — a stage to be gotten over. Maybe truly great intelligence manifests itself in a tendency towards contemplation and a calm acceptance of limits. Maybe there are countless societies in the universe far superior to our own who are invisible to us because they have learned the great blessings to be had when you just mind your own damned business.