I am not sure if my understanding is correct about how commas must be used in case of a pronoun "you" and an appositive.
The wikipedia page on apposition says:
And The Blue Book of Grammar says:
So, from these two sources I gather that if the scope of possible meanings of the following appositive is narrower than that of the preceding identifier, then commas are not needed:
My teacher Jim McAlister was here yesterday.
Here the scope of possible meanings of Jim McAlister is definitely narrower than the scope of my teacher; therefore, there are no commas.
But what if the preceding identifier is simply pronoun "you"?
Naturally, I would think that "you" would always imply the number of people the speaker is addressing, but the following example made me think otherwise:
Here Rameses is speaking only to Moses, but his point is that all of Hebrews have been a big trouble, not just Moses.
This example shows that "you" may not mean exactly those people who are being addressed or spoken to.
If so, then whatever identifier would be placed as an appositive right after "you" will always be narrower in scope of its possible meanings (than the scope of meanings of "you") because it will always be specifying which one of the possible meanings of "you" is exactly meant. Therefore, as far as I understand, in case of "you" and an appositive following right after it, commas are never needed.
However, I keep seeing again and again such sentences like:
You, the teachers, should bear a bigger responsibility.
You, Mr. Robertson, have failed to report to the captain.
I see such sentences in many authoritative sources and, as can be seen in the examples, commas are always used around the appositives in them. Why is it so? How does it go along with the rules of using commas in such cases, as described in Wikipedia and in Blue Book of Grammar?
Best Answer
"You X" - without commas - evidently does not follow the traditional rules of restrictive/non-restrictive apposition set forth in your question. The construction is used, as far as I can come up with, in three different ways:
This is your given example - "You Hebrews have been nothing but trouble." "Hebrews" is the group to which the statement applies - i.e., presumably Rameses is referring to all Hebrews. "You" simply adds that the person or people being directly addressed by the speaker are understood by all to be members of this group. As mentioned by others, referring to an ethnic group in this manner today will typically be taken with offense.
Take, for example, "You geniuses have finally solved the problem that I thought was impossible to solve!" Someone might say this to a person on a team that solved a really hard problem. The person is not referring to all geniuses - he's only referring to the people on the team that solved the problem. Further (unlike usage 1, above) it need not be understood beforehand that the people to whom the statement is addressed actually are geniuses - the speaker may well be using this utterance as a way to state his view that the team members are geniuses (which may be more of a compliment than something intended to be taken as literal truth).
"You guys", "you people", etc., to some extent fall into this category. Obviously the statement is not intended to refer to all "guys" or "people" - it is rather intended to refer to some smaller group, which is implied from context.
This identifies the person as an X. "You filthy liar!" is an example. However, unlike the plural versions, the singular version can't be a subject of a sentence. "You saint are always thinking of others" isn't possible. Instead, say: "You saint - you're always thinking of others."
Note that in all of the above examples, articles aren't used. "You the Hebrews are nothing but trouble" would sound completely wrong. However, if commas are involved, the typical rules of non-restrictive apposition appear to apply and you'd expect an article: "You, the Hebrews, have been nothing but trouble." This would be more appropriate if Rameses were addressing a crowd of all of the Hebrews, or possibly a single person, if Rameses viewed that person as a representative of the Hebrews. Like Moses.