Yesterday I made a snarky post about people who think that "who" refers only to human beings and that "that" can only refer to animals and inanimate objects. Today I get a wait, wait!: How are we supposed to teach this?
Let's go together down this well-traveled road.
First, we have to dispose of a venerable superstition. Many people think that to use "that" referring to a person is dehumanizing, reducing that person to an inanimate object or animal. But Bryan Garner points out that speakers of English have been using "that" to refer to people for thirteen centuries (we're about to see how and when). If using "that" to refer to people is not to your taste, don't use it. But you do not get to impose your personal preference on the rest of the language.
"Who's" on first. "Who" refers to people (and yes, Associated Press Stylebook, named animals). But its possessive form "whose" can refer to people, to objects ("a tree whose leaves turn red in autumn"), and to abstractions ("an idea whose time has come").
Now take "that": In contemporary usage, Garner points out, "that" refers to things in 90 percent of uses, but to persons in the remaining 10 percent. "That" is perfectly acceptable in standard English in contexts that refer to a group of people or to a person whose identity is unknown.
"The people that walked in darkness have seen a great light" you may have sung in Handel's Messiah. For a more recent example than the KJV, there are Irving Berlin's "The Girl That I Marry," Mark Twain's "The Man That Corrupted Hadleyburg," Ira Gershwin's "The Man That Got Away."
The teachers and usage authorities that endorse the superstition, unfortunately, outnumber the editors that attempt to uphold informed usage.
