Learn about the importance of this elite category of modifiers.
Not all modifiers are created equal!
All noun modifiers, by definition, give additional information about the noun they modify. BUT, the importance of that additional information can vary significantly. Consider the following two sentences, both with modifiers underlined.
1) Last year, I visited the Chartres Cathedral, which is considered the principal exemplar of Gothic architecture.
2) The man who lives next door to me has three large dogs.
Both have a relative clause modifier, and both provide information about the noun they modify. Now, consider these sentences, with those modifiers removed.
1) Last year, I visited the Chartres Cathedral.
2) The man has three large dogs.
The first sentence is still perfectly clear: it leaves absolutely no doubt where I went last year (because there is only one Chartres Cathedral in the entire world!). In contrast, the second sentence leaves us in the dark. The natural question evoked by that sentence is “What man? About whom are we talking?” There is something essential now missing from this second sentence.
These two exemplify the difference between an ordinary modifier and a “vital modifier.” A vital modifier is essential to establish the identity of the noun in question, and omitting it leaves an important question unanswered. A non-vital, ordinary modifier may add interesting information, but it is not necessary to establish the identity of the noun.
The post on restrictive clauses already explored an aspect of this topic. A restrictive clause is always a vital modifier. A non-restrictive clause is always a non-vital modifier. That post also made another important distinction: non-vital modifiers should be set off from the rest of the sentence with commas, but vital modifiers should not have commas (notice that #1 above has a comma, and #2 doesn’t).
Exception to the Modifier Touch Rule!
This is a biggie! In general, a modifier should touch the noun it modifies. For example, this sentence would be considered faulty on GMAT SC.
3) I am going to the show with my friend Kevin, who likes Elvis, the nicest person I know.
This sentence is a train wreck! The appositive phrase modifier “the nicest person I know” is currently next to Elvis, so it implies (a) somehow I know Elvis (who has been dead for 35 years!), and that (b) Elvis is the nicest person I know, contrary to at least some appraisals of the man. Clearly, the modifier “the nicest person I know” is supposed to modify Kevin, but because its placement violates the Modifier Touch Rule, it creates a grammatically unacceptable sentence that would always be wrong on GMAT SC.
By contrast, consider this sentence:
4) The workers at the envelope factory, having been on strike for seven weeks, were finally close to a settlement with management.
The participial phrase “having been on strike for seven weeks” is a modifier. It can’t modify “envelope factory” — the building itself can’t go on strike. It must modify “workers”, so naively one might assume this construction also violates the Modifier Touch Rule. Nevertheless, this sentence is 100% grammatically correct. The prepositional phrase “at the envelope factory” is also a modifier, and it is a vital noun modifier: without that phrase, we would have no idea which “workers” were being discussed. A vital noun modifier can come between a noun and another non-vital modifier. This is the big exception to the Modifier Touch Rule. By the way, notice that the vital modifier “at the envelope factory” has no commas separating it from “the workers”, but the non-vital modifier “having been on strike for seven weeks” is set off by commas from the rest of the sentence.
If you understand the important distinction of vital vs. non-vital modifiers, you will master one of the subtlest categories on GMAT Sentence Correction.