That/Which

[AAllan at AOL.COM]

There is the expected very full historical discussion in Merriam-Webster's
Dictionary of English Usage, s.v. "that." Just one little part of it reports
Virginia McDavid's study in _American Speech_ for Spring-Summer 1977, showing
"that about 75 percent of the instances of _which_ in edited prose introduce
restrictive clauses; about 25 percent, nonrestrictive ones."

I've had some editors conduct "which hunts" in my mss. and have been able to
point out smugly how many restrictive "which"s they've missed because those
sound so natural. - Allan Metcalf