The Fermi paradox is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilizations and the lack of evidence of contact with such civilizations. (That sentence was shamelessly borrowed from Wikipedia.) Of course there are many different theories trying to explain this paradox.
The paradox becomes most interesting when it is considered with reference to human nature. Is an intelligent species inherently self destructive, for example? Consider all the “scary” technology we are developing, with The Bomb probably the original “Weapon of Mass Destruction”. (Today is the first time I noticed that “mass destruction” is a pun, when dealing with nuclear weapons. )
A couple of days after I first looked at that Wikipedia page, Steve sent me a link to an article titled Why We Haven’t Met Any Aliens. The article considers “runaway consumerism and virtual-reality narcissism”.
I will be referring back to this post/article later, when I have time to discuss some ideas or thoughts that are related to it.