The Search for Extraterrestrial Intelligence, or SETI, made assumptions quite different from Stephen Hawking's dire warnings about aggressive alien life. Should we keep looking? David Kaiser at the London Review of Books finds that the West's most passionate search for alien life, SETI, assumes that alien life would be much like human life and alien reasoning like human reasoning. But is that too big a leap? SETI uses scientific standards in its search, but "who is to say that other advanced civilisations – even if they pursue something like scientific investigation – would carve up the confusion of nature in the same way as we do?," asks Kaiser.