Where Are The Aliens?

Alex Steffen links to Geoffrey Miller's explanation for the Fermi Paradox: if there are aliens out there, why haven't any of them contacted us? Miller's argument, in a nutshell, is that any civilization advanced enough to build an interstellar spaceship is also advanced enough to build an interstellar space ship video game, and the latter is easier and more fun. So the aliens haven't contacted us because they're all playing Xbox (or because they spent so much time playing Xbox that they forgot to have sex and died out).

The Xbox hypothesis (which actually rests on some interesting ideas about fitness versus crude proxies for fitness) may well explain the fate of some alien civilizations. But both the original hypothesis and Miller's resolution make a huge assumption: that exploring the universe is an obviously good and rational thing for a civilization to do, if it can. But while wanderlust may be an important feature of modern Western culture, I see no reason to assume it as an interplanetary universal.

What we really need to ask is: why would a species start exploring the universe? Particularly at the early stages, space travel is likely to be a hugely expensive and difficult undertaking -- so a small shift in alien psychology or social organization could nip it in the bud. Why wouldn't they be happy staying at home? And if they're playing Xbox at home, what of it? Evolution is an explanation of a factual process, not a moral imperative (although it's certainly tempting to blur that line, in order to give the imprimatur of scientific proof to one's moral convictions). Going out in a bang of Halo-induced extasy is no more irrational than an individual dying peacefully after a good life.

But even if the long-term perpetuation of the species is of value, it's not necessarily irrational for a species to eschew space travel. Going to other planets could invite conflict with other civilizations (perhaps ending in nuclear annhialation of one side), or dangerous invasive species or diseases being brought back to the home planet. Or there could be major domestic consequences -- perhaps space travel diverts precious resources from more pressing problems, or requires an oppressive hierarchical social structure that the aliens find intolerable. This is not to say that these are conclusive arguments against space exploration by humans. But they are plausible enough that only a small difference in the aliens' psychology (their attitude to risk, their facility for certain types of social organization, etc) would make them conclusive for the aliens. Evolution is a shortsighted satisficing, not farsighted optimizing, process. So we have no reason to think that human psychology is average for what an intelligent species would evolve, as opposed to being an outlier (and this is assuming that humans will eventually explore space -- a prospect I find a bit dubious).