What if there are no extraterrestrial civilizations? Or at least, what if they exist, but have no desire or intention of communicating with us, or exploring other stars, or contacting anyone else?

The classical model for SETI teeters precariously on a very unstable pyramid of provincial assumptions. Sure, there is a lot of circumstantial evidence that life is probably very common in the cosmos, but even if we concede that, look at all the other hurdles that have to be jumped and needles that have to be threaded before we pick up a signal, or encounter a probe, or they do the same for us.

First, we have to assume that they are not only intelligent, but that their intelligence is keen on physics, astronomy and other sciences necessary for space travel and communications. We have to further assume they have the planetary resources and social organization to do this–and the psychological motivation to want to.

Even assuming that, why should they want to? Surely if they got that far they would realize that fixing their own planet for sustainable long-term existence is a lot easier than terraforming new ones. They might fully industrialize their entire solar system, and perhaps do the same with some neighboring stars, just to give themselves some backup if their world ever became uninhabitable, but why should they spread across the galaxy? Our own space groupies fantasize about playing the space conquest game, but thatr’s how space groupies think. For ET, perhaps one lump of frozen slag and ice is pretty much the same as another. The asteroid belts and gas giant satellites of nearby stars would probably differ little from their own. Why bother? Once they had a few under their belt, there would be little reason to add any others.

Species immortality? It might be safer in the long run to keep a low profile, not spread around until you ran into some nasty neighbors who could follow you home. It might make more sense to find a quite, inconspicuous, long-lived red dwarf with a lot of orbiting rocks that could be tunneled into safely. Surely, any species with the ability and desire for interstellar travel would soon realize that most habitable or transformable systems are pretty much alike, and the really interesting ones are violent, unstable and best studied from a safe distance. A sparefaring species would have excellent astronomical equipment to satisfy their scientific curiosity–and make sure no other civilizations were around that might want to visit.

Do we really know any of this? Obviously not, and in an infinite universe there probably is one of every type out there, “What is not forbidden is mandatory!”

But that’s my whole point. Most of our speculation about ETI assumes they are a lot like us, or at least, a lot like those of us who enjoy speculating on these issues.