That With Which I Will Put Up
In the one camp are people who think that and which should be used in different circumstances, exclusively. They feel those differences are vital.
In this camp, that is a word that restricts meaning; which does not. Which adds information but is not necessary to understanding the main clause. Satellites will fall from the sky if the spec docs use which where that applies.
The other camp contains what Editing Canadian English calls “language authorities [who] increasingly concede that which can introduce either type of clause.” ECE is a publication of the Editor's Association of Canada.
Camps like these are where grammar gang wars start.
According to Mark Pilgrim, hold-outs in the first camp are ignoring some pretty old and respected evidence: Dickens, Carroll, Stoker, Conrad, Melville, and Bronte all used which the “wrong” way.
“The copy editors are enforcing a rule which has no support at all in the literature that defines what counts as good use of the English language.” That’s what Mark said in a post on the U of Penn Language Log. And Mark is a technical writer who just may be concerned with satellites falling from the sky.
Having this non-rule imposed on his own writing created a hostile environment for poor Mark. He just about pops a vein in his Language Log post. This reminds me that the first rule of editing is “do no harm,” and that harm can be done to authors as well as to prose. How much time is spent “correcting” according to “rules” that are disputable? I hope it’s not why Mark quit the internet.