I need help understanding 'restrictive' phrases.
It's well known that non-restrictive phrases are inessential to the meaning of the sentence because they
do not limit the reference of a word or phrase.
But does that mean that all non-restrictive phrases say something that is nonarbitrary? That seems, superficially, to be the exact opposite?
I don't mean to suggest these examples are grammatically correct. I am just trying to show what I mean by 'non-arbitrary'. Neither that all of them are strictly speaking "nonrestrictive phrases", only that they are phrases that are not restrictive.
A simple example:
My sister, Susan, likes shopping.
'Susan' does not limit the meaning of 'sister' in the rest of the sentence, so 'Susan' likewise already has its referent fixed by the rest of the sentence, as well as I suppose context. What it says about my sister is nonarbitrary.
The first sentence, which I quoted, is from the dictionary.
This non-restrictive phrase does not limit meaning. What it says about the first sentence is nonarbitrary, because the first sentence already has its referent, and the phrase just adds that it was a quote.
In effect I'm asking whether non-restrictive phrases have a non-arbitrary meaning due to the rest of the sentence, despite themselves being inessential to the sentence.