‘I don’t think that word means what you think it means,’ says the Spaniard Inigo Montoya in the film The Princess Bride, when Vizzini keeps saying it is ‘inconceivable’ that the Dread Pirate Roberts is still on their tail. I muttered those words to myself during a parliamentary debate just before the start of the latest lockdown, when the minister twice said that the wave of infections was increasing ‘exponentially’.