I was surprised to find Jay Livingston, an intelligent and sensible person, subscribing to the prejudice that words like which and this, when understood as referring to some situation or proposition alluded to in the preceding discourse, should be shunned as "non-reference pronouns".
On the contrary, it seems clear that (what Arnold Zwicky calls) "summative" expressions normally do have referents, that summative reference helps makes discourse coherent, and that summative use of which and this is generally no harder to understand than the alternative ways of accomplishing the same goal.
In my post this morning, I gave a few examples of well-regarded writers using summative which. I started with Shakespeare, and most of the other examples were from poetry as well; but some people (like Jay's high-school English teacher, Miss Elliott) discount such examples as poetic license, so I thought I'd add some evidence from expository writing.
But first, let's consider the argument that such evidence is intended to support.