“A Few Bad Apples”

Geoff Nunberg traces how the proverb shifted meanings:

In 19th century America, it was a staple of Sunday morning sermons: "As one bad apple spoils the others, so you must show no quarter to sin or sinners." Or it could suggest that finding one malefactor in a group should make you suspicious of everybody else. "A bad apple spoils the bin," one journalist wrote in 1898 of the Dreyfus Affair; if one officer is capable of forgery then why wouldn't others be as well?

Back then, nobody ever talked about "just a few bad apples" or "only a few rotten apples" — the whole point was that even one was enough to taint the group. These days, those are the phrases people use to imply that some misdeeds were an isolated incident — a couple of rogue cops, a handful of unprincipled loan officers, two or three sociopathic soldiers. That's a counsel of moral realism: as in, there's evil in the world; get over it.