Social concerns PERSON@1 believed that the PERSON@2 equation , on substitution of reasonable guesstimates , suggested that a large number of extraterrestrial civilizations would form , but that the lack of evidence of such civilizations highlighted by the Fermi paradox suggests technological civilizations tend to destroy themselves rather quickly .

Social concerns PERSON@1 also believed that the PERSON@2 equation suggested that many kinds of intelligent life could form , but that the lack of evidence -LRB- the Fermi paradox -RRB- suggests that intelligent beings destroy themselves rather quickly .
