Dear Ms. G:
You wrote:
> Just for your information, I saw a spot in the Run-on Sentences section that
> misused which/that. In the second sentence: “Sometimes even sentences which
> are technically correct …”, the “which” should be a “that.” On a grammar
> web site, that may be something you’d like to correct. Thank you!
>
May I ask why? It seems that either is OK here. Either word can refer to
things.
You wrote:
> Hello James!
>
> “That” is technically correct in the given sentence. It’s a matter of
> nonrestricive clauses vs. restrictive clauses, also known as nonessential
> and essential clauses.
>
> Restrictive/essential clauses follow and limit the words they modify. They
> are essential to the meaning of the main clause and are not set off by
> commas. Nonrestrictive/nonessential clauses are not essential to the meaning
> of the main clause and may be omitted. These clauses ARE set off by commas.
>
> The clause in the given sentence is important to its meaning: “Sometimes
> even sentences that are technically correct …” It is an essential clause
> because it determines the meaning of what comes next in the sentence.
> Therefore, the word “that” should be used, and the clause should not be set
> off by commas.
>
> If the clause is nonessential, and is thus not important to the sentence but
> just mentioned as an aside, it would use “which” and be set off by commas.
> In that case, you’d be talking about all sentences, and interjecting “which
> are technically correct.” However, in the sentence we’re talking about, the
> whole point is that a sentence can be technically correct and still
> [whatever the next part of the sentence is].
>
> The following links provide good explanations. Let me know if you think I’m
> incorrect on this. Thanks!
> http://www.grammarbook.com/grammar/whoVwhVt.html
> http://www.odyssey.net/subscribers/english/engcons4.html
>
Yes, the comma is helpful to distinguish restrictive from nonrestrictive modifiers, but using “that” for one and “which” for the other does not appear to be a pattern that is followed regularly by anyone. It’s like the
“no adverb in the middle of an infinitive” pattern; it might serve a purpose in understanding grammar, but it is not anything that serves a useful purpose in communication and is often honored in the breach. And frankly, it can be an annoyance when it pops up on certain grammar checkers because the checker cannot make the subtle distinction you make here.