Can pronoun "which" be used to introduce an independent clause?

Question

As it turns out, the phrase “keeping up with the Joneses” derives from a cartoon strip of that name that launched in 1913 and ran for 26 years. In the strip, creator “Pop” Momand poked fun at our need to do things in order to impress other people. I’d love to say that need vanished when the last episode of that comic strip ran, but alas, it seems to have only gotten worse. These days we don’t care about the Joneses, we’re trying to keep up with the Kardashians. (Thank God I don’t have cable TV!)

Which really gets to the core of the matter? Who is telling us that we need to keep up with the Kardashians? The media. Until the late 1880s, magazines were not widely read...

Am I correct in thinking that the "which" in the first sentence of paragraph 2 is used to refer back to the preceding paragraph and thus the question mark should be period instead?

Answer 1

Yes, "which" is used like a relative pronoun that refers to the entire contents (or the main idea) of the first paragraph. And yes, that sentence probably should not end with a question mark. There might be some stylistic reason the author chose a question mark, but it was probably supposed to be a period. A colon would have fit nicely too.

According to Merriam Webster, "which" here is "used as a function word to introduce a relative clause". Relative clauses are dependent clauses. Which means (see what I did there?) it's neither an independent clause, nor a dependent clause as part of another sentence.

It's called a sentence fragment, or an incomplete sentence. Wikipedia describes it as:

a set of words that does not form a complete sentence, either because it does not express a complete thought or because it lacks some grammatical element, such as a subject or a verb. A dependent clause without an independent clause is an example of an incomplete sentence.

Answer 2

This appears to be an error.

As written it mean "Which (one of the options that you know are available) is about the essential facts of this matter?" As written it is a rhetorical question. But this makes no sense in context. No options have been mentioned in the text.

So it is almost certainly a mistake, and the author should have written it as a relative clause, with a comma before which, and no question mark.

I think this is a computer grammar checker fail. The parenthetical sentences made the grammar checker think that "Which" must start a new sentence, and since it forms a syntactically correct question, the grammar checker has added a question with a question mark, and the author hasn't noticed the mistake.

The author should have rephrased it. Instead of using a relative pronoun, they could have used a demonstrative: "This really gets...". (Discourse deixis)