The Brexit referendum will probably be the defining political event in the UK over the next few decades. But to know whether leaving or remaining is actually a good idea requires tremendous social scientific knowledge–knowledge that most Britons lack. The day after the referendum, in the UK, there was a sharp spike in Google searches asking exactly what the EU is and what leaving it will do. This suggests many Britons voted first and did their homework second. Already, many UK voters express regret.