"something which" or "something that"

Question

According to Korean English grammar books, nouns that ends with "thing", such as something, anything, generally take "that" as a relative pronoun.

But does that mean that "something which" is not preferred? If so, are there any rules?

It is not just the newness of contemporary literature that makes it different, but also the context in which it is written and received, something which gives it a very interesting edge over the literature of the past. (excerpt)

In the sentence, "something which" is used because "which" can be used as non-restrictive, but "that" cannot be used so?

Answer 1

It is traditionally accepted to use that for a restrictive clause and which for a non-restrictive clause.

In modern English usage, “that” always introduces a restrictive clause (due to which it is almost never set off by commas).

• The box that lies on the table is empty. (correct)

In British English, it is absolutely fine to use “which” in restrictive as well as non-restrictive clauses.

• The box which lies on the table is empty. (correct in British English)

This sentence above is usually perceived as incorrect in formal American English.

Extra information:

There are several issues with this rule. First of all, it is a prescriptive rule, and most Americans don’t strictly follow it in speech (many being unaware of its existence altogether). Secondly, when “which” is combined with a preposition, noun, or a pronoun, it cannot be replaced by “that”, even when it introduces a restrictive clause (this is considered to be an exception to the rule), as in:

• The principle in which he believes has been proved wrong. (correct)
• The principle in that he believes has been proved wrong. (incorrect)

Answer 2

"which" refers to the state of being (e.g. characteristics, specifications) of an indicated noun, almost as if one would afterwards want to add some comments (e.g. adjectives) to the noun for a broader view or perspective.

If this is not the intention and the context needs no further explanation, then the use of "that" is common rule.

Remark: when a preposition needs to be used to refer to the noun, always combine with "which".