If not who, which?

Mark asked (he knows I live for this kind of thing):

I have a grammar question: Is it correct to use the pronoun "which" to describe a person, as in "They were the people which were represented by stone pillars...." Or must it be "They were the people who were..."

According to Merriam-Webster's Concise Dictionary of English Usage and The New Fowler's Modern English Usage, it's neither grammatically incorrect nor unprecedented in usage to use which (or that) to refer to people or entities that consist of people. Examples abound.

For instance, older translations of The Bible have these versions of a well-known line:

Our Father which art in Heaven (1611)

and

Our Father that art in Heaven (1885)

before settling on:

Our Father who art in Heaven

That duly acknowledged, however, both MW and Fowler's agree that it is more common and more widely accepted to use who for references to people. This move also means that you don't have to worry about whether the relative pronoun is part of a restrictive clause. (Should the which be a that or vice-versa and does it matter? If you use who, it's the same pronoun either way.)

Anywho, this is all just a long-winded way of recommending that you use who. But know that if you decide against it, you're neither wrong nor in poor company.