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.
Given a corpus of bad writing, we could no doubt find many examples of distracting or confusing reference, comprising many types of referring expressions and many types of referents. In some of these cases, the writer will have used one of the many alternative ways of referrring to facts, situations, ideas, questions, etc., that were mentioned or evoked in the previous discourse, and we'll get the referent wrong, or be distracted by uncertainty about what the referent should have been.
Will we find that all the confusions and distractions of this type involve one of the proscribed forms of summative reference like which or this, while all the cases of (for example) abstract nouns used for the same purpose are perfectly clear and easy to understand? Surely not.
Will we even find a statistical tendency in that direction? I have no idea. It wouldn't be terribly hard to find out, but as far as I know, none of the people who feel so strongly about enforcing such prescriptions have ever tried to do any research to investigate this question. (Or indeed any other questions — but the curious lack of prescriptivist science or even scholarship is a topic for another post or two. I'll just note in passing that I'd be happy to endorse stylistic recommendations that were based on sound reasoning from valid evidence.)
Given the lack of systematic studies about reference problems in bad writing, the only real evidence we have comes from good writers. And there are two question that this evidence bears on: are summative pronouns ungrammatical in standard English? and given that they're grammatical, do good writers tend to avoid them for stylistic reasons?
The fact, as far as I can tell, is that good writers have always used a mixture of methods for summative reference, depending on their individual stylistic preferences; in the hands of a good writer, all of the methods work well; and the use of summative anaphors like which, this and that is a common ingredient in the mix. This establishes, as a matter of practical fact, that summative pronouns are not ungrammatical in standard English, and that there is no general stylistic reason to avoid them.
Evidence for this view can be found by examining the works of well-regarded writers over the centuries.
For example, if we search for the pattern "this is" in John Stuart Mill's Utilitarianism, we find many examples of summative this. In none of them, I submit, would his meaning be any clearer if "this fact" or some similar expression were substituted. Nor, I think, is any other editing needed — it's clear enough what Mill means. Here are a few examples among many:
Considerations may be presented capable of determining the intellect either to give or withhold its assent to the doctrine; and this is equivalent to proof. [this = presenting considerations that determine the intellect to assent or not]
To give a clear view of the moral standard set up by the theory, much more requires to be said; in particular, what things it includes in the ideas of pain and pleasure; and to what extent this is left an open question. [this = the question of what is included in the ideas of pain and pleasure]
It may be objected, that many who are capable of the higher pleasures, occasionally, under the influence of temptation, postpone them to the lower. But this is quite compatible with a full appreciation of the intrinsic superiority of the higher. [this = occasionally postponing the higher pleasures to the lower]
They say it is exacting too much to require that people shall always act from the inducement of promoting the general interests of society. But this is to mistake the very meaning of a standard of morals, and to confound the rule of action with the motive of it. [this = arguing that it's too much to ask people to always be motivated by the general interests of society]
Similarly in Bertrand Russell's Problems of Philosophy:
The painter wants to know what things seem to be, the practical man and the philosopher want to know what they are; but the philosopher's wish to know this is stronger than the practical man's, and is more troubled by knowledge as to the difficulties of answering the question. [this = what things are]
We are all in the habit of judging as to the 'real' shapes of things, and we do this so unreflectingly that we come to think we actually see the real shapes. [this = judging the 'real' shapes of things]
Other philosophers since Berkeley have also held that, although the table does not depend for its existence upon being seen by me, it does depend upon being seen (or otherwise apprehended in sensation) by some mind–not necessarily the mind of God, but more often the whole collective mind of the universe. This they hold, as Berkeley does, chiefly because they think there can be nothing real–or at any rate nothing known to be real except minds and their thoughts and feelings. [this = the belief that the table's existence depends on its being perceived]
Thus if we cannot be sure of the independent existence of objects, we shall be left alone in a desert–it may be that the whole outer world is nothing but a dream, and that we alone exist. This is an uncomfortable possibility; but although it cannot be strictly proved to be false, there is not the slightest reason to suppose that it is true. [this = the notion that we alone exist]
Of course, Mill and Russell are aware of alternatives like "this question", "this fact", "this conclusion", "this possibility", etc., and sometimes they use them. Here are some examples from the same Russell essay:
Is there any knowledge in the world which is so certain that no reasonable man could doubt it? This question, which at first sight might not seem difficult, is really one of the most difficult that can be asked.
So long as we are dealing with derivative knowledge, we have the test of intuitive knowledge to fall back upon. But in regard to intuitive beliefs, it is by no means easy to discover any criterion by which to distinguish some as true and others as erroneous. In this question it is scarcely possible to reach any very precise result: all our knowledge of truths is infected with some degree of doubt, and a theory which ignored this fact would be plainly wrong.
We may therefore admit–though with a slight doubt derived from dreams–that the external world does really exist, and is not wholly dependent for its existence upon our continuing to perceive it. The argument which has led us to this conclusion is doubtless less strong than we could wish, but it is typical of many philosophical arguments, and it is therefore worth while to consider briefly its general character and validity.
It might happen, if Kant is right, that to-morrow our nature would so change as to make two and two become five. This possibility seems never to have occurred to him, yet it is one which utterly destroys the certainty and universality which he is anxious to vindicate for arithmetical propositions.
Are these examples, which use "this N", systematically clearer than the earlier examples that used plain "this"? Plainly not, in my opinion. In some cases "this N" is better, and in some some cases "this" is better; and I believe that Mill and Russell have made the right choice in each case.
Clarity is good. But let's not clutter the minds of students — and editors — with groundless superstitions about how to achieve it.