Thucydides on Donald Trump
‘America’s journey into the great unknown’, screamed a headline greeting Donald Trump’s election as next President of the United States. Most of us call it the future, which has a long and distinguished tradition of being unknown. In the ancient world there was quite an industry in attempting to foretell the future: oracles, auguries, dream interpreters and so on. But to rely on the supernatural was to put one’s trust in something equally unknowable, and the great Greek historian Thucydides (5th century BC) proposed a better way: as doctors’ evidence-based analysis of the course of an illness enabled them to generalise about the course of any future example, so human