This week we learned that parents who are unsure whether to have their children vaccinated against dangerous diseases are in the grip of “vaccine hesitancy”, a term that first appeared in print in 2008 but is becoming distressingly more common. It is not clear whether there is a symmetrically opposed group who are “vaccine curious”, but to call such waverers “hesitant” is at least gentler than calling them “deniers”.

The word “hesitant” itself is first recorded in 1647, when the Roman emperor Hadrian was said to be “hesitant, or halting”. It comes from the Latin haesito, meaning to stay in one place, and so to vacillate or remain undecided. But sometimes those who decide fastest are the stupidest, and hesitancy has been described as the sign of a fine mind.

In 1768, the philosopher Abraham Tucker described meeting a friend at the Inns of Court: this “man of gravity” spent a full quarter of an hour unable to decide which way he’d like to go for a walk. “Such hesitancies as these,” Tucker comments generously, “are weeds of the richest soils.” Rather than calling reluctant parents “anti-vaxxers”, it’s probably better to flatter them thus into doing the right thing.