EXCERPT Aristotle, living during the fourth century BC, found himself philosophising during a time when material conditions did not discernibly change over the course of a human lifetime. So perhaps we can’t blame him for assuming that human civilisation would look the same in the future as it did in the past. His reasoning was as follows: if all possibilities are to be considered possible only in so far as they have previously been realised, then this also applies to technological discoveries and human knowledge. All discoverable things have already been discovered; all thinkable things previously thought; all forms of government already assessed; all workable feats of engineering tried and tested. In ‘the multitude of years […] almost everything has been found out’, he concluded: ‘each art and science has often been developed as far as possible and has again perished’. In a thought reminiscent of Plato’s innumerable prior civilisations, he added that these possibilities have been assayed ‘not once nor twice nor occasionally, but infinitely often’. Again, perhaps this was not entirely unreasonable to assume, given that we do not live amongst the ruins or the rubbish heaps of older civilisations with vastly more advanced technologies and capabilities. But if ‘things have been invented several times over in the course of ages, indeed infinitely many times’, this means that inquiry is essentially just the rediscovery of past knowledge. ‘We should therefore make the best of what has been already discovered, and try to supply defects’, Aristotle concludes. And there is a further consequence of such thinking: it also implies that all plausible risks and threats have already been encountered and experienced. By definition, this precludes and prevents thinking about X-risk since, by definition, no one lives to tell—or even to forget and then rediscover—that particular tale.…