The Relative Pronouns "That" and "Which"

Note well that this debate does not directly concern conjunctions, pronouns, or determiners. In this debate, we are merely discussing the uses of "that" and "which" as relative pronouns. For those in the audience not familiar with what a "relative pronoun" is, I recommend this webpage: . http://englishplus.com... Formalities aside, we begin. I shall first set out to prove that there is no historical precedent for such a separation. Let us take for example the first few pages of Orwell's classic novel "1984": ---> "It was one of those pictures which are so contrived that the eyes follow you about when you move. " ---> "Inside the flat a fruity voice was reading out a list of figures which had something to do with the production of pig-iron. The voice came from an oblong metal plaque like a dulled mirror which formed part of the surface of the right-hand wall. " ---> "He moved over to the window: a smallish, frail figure, the meagreness of his body merely emphasized by the blue overalls which were the uniform of the party. " Or, for a more modern example, the first few pages of Ian McEwan's classic "Atonement," published in 2001: ---> "The play told a tale of the heart whose message, conveyed in a rhyming prologue, was that love which did build a foundation on good sense was doomed. " ---> "She took her daughter in her arms, onto her lap. .. and agreed instantly, murmuring into the tight whorl of the girl's ear, that this word could be quoted on the poster which was to be on an easel in the entrance hall by the ticket booth. " ---> "At the age of eleven she wrote her first story--a foolish affair, imitative of half a dozen folk tales and lacking, she realised later, that vital knowingness about the ways of the world which compels a reader's respect. " Or, if you want an American example, consider American journalist Roger Ebert's op-ed piece, entitled "How I believe in God," published in April 2009: ---> "Those words always introduced a hypothetical situation which led the unsuspecting Catholic perilously close to the fires of Hell. " ---> "My father in any event was a non-practicing Lutheran, until a death bed conversion which rather disappointed me. " I could list example after example--the ones I've listed are merely those which I've recently encountered--but I'll move on. Simply note that many professional English writers do not distinguish between the relative pronouns "that" and "which. " The following can be found on Washington State University's website, and is written by Paul Brians, a Professor of English there (. http://www.wsu.edu...): ---> "I must confess that I do not myself observe the distinction between 'that' and 'which. ' Furthermore, there is little evidence that this distinction is or has ever been regularly made in past centuries by careful writers of English. " This is from the American Heritage Book of English Usage: ---> "Some people extend the rule and insist that, just as 'that' should be used only in restrictive clauses, 'which' should be used only in nonrestrictive clauses. .. . This use of 'which' with restrictive clauses is very common, even in edited prose. If you fail to follow the rule in this point, you have plenty of company. Moreover, there are some situations in which 'which' is preferable to 'that'. .. " The following is from EnglishPlus. com (. http://englishplus.com...): ---> "Some teachers also tell you that 'that' should be used with restrictive modifiers and that 'which' should be used with nonrestrictive modifiers. Historically, there is little evidence that this 'rule' ever had a significant effect on English expression, but writers should be aware that some correspondents have been taught this practice. " Thus, it is my contention that the relative pronouns 'that' and 'which' are entirely interchangeable. I have presented my case, and await my opponent's response.