Whenever we have two or more distinct nouns (or pronouns) in the same noun phrase – most frequently separated by the conjunction ‘and’ – we might need to pay a bit of attention to make sure the forms of the nouns work together.
- What’s the difference between “you and I” and “you and me”?
- What’s the difference between “Jack’s and Jill’s” and “Jack and Jill’s”?
- Why is “Bonnie and Clyde are …” correct when “Bonnie and Clyde is …” sounds better?
There are two key things to keep in mind: parallelism and grouping.
You can think of parallelism as the idea of keeping two (or more) items on the same playing field. You can substitute one for the other, and while the meaning will change, the grammar should remain the same.
For example, suppose you might say “Alan gave you a hug.” You could switch out the personal pronouns for a new sentence: “Alan gave me a hug.” To apply both pronouns to this situation, you’d say “Alan gave you and me a hug.” It would be incorrect to say “Alan gave you and I a hug” because it’s incorrect yo say “Alan gave I a hug.”
Another way to think about it is that all items in a list (even a list of two) should have the same specific part of speech. When ‘you’ is used as a subject, it can be accompanied by the subject ‘I’. But when ‘you’ is used as an object, it should be accompanied by the object ‘me’. The reason this particular example is often a source of confusion is that the 2nd-person subject pronoun ‘you’ is identical in form to the 2nd-person object pronoun ‘you’; it’s much easier to see parallelism in “she and he” vs. “her and him” (one would never say “she and him” or “her and he”).
Often, a list is treated as a single group within its sentence, rather than the multiple individual items that make up the list. At the top of this post, I used the example “Bonnie and Clyde are …” ‘Bonnie and Clyde’ could be replaced by ‘they’ or ‘the bandits’. Since you would say “they are” or “the bandits are“, you must then also say “Bonnie and Clyde are“.
Sometimes we’re inclined to use only the last noun in a list for the subject phrase to determine the form of the verb. Since “Clyde is” is correct, “Bonnie and Clyde is” might erroneously seem correct to some people.
Granted, most English speakers are not fooled by that example, but longer subject phrases can be more problematic. Consider “The woman I met last weekend at that conference and her husband like to go dancing”. That sentence is correct, even though “her husband like” sounds wrong (because it would be wrong on its own; but instead it’s “the woman … and her husband like”, or “they like”). As teachers, this is something we need to keep an eye out for when our students start making longer sentences.
Some groups are optional. There is a difference between “Jack and Jill‘s pails” and “Jack‘s and Jill‘s pails” (and yes, both are grammatically correct). The former refers to pails that the two of them own together. The later refers to their separate pails; it might be identical to “Jack’s pails and Jill’s pails”. It’s the difference between “their pails” and “his and her pails”.
The thing to keep in mind is that in the first phrase, the apostrophe s does not follow “Jill” solely, but “Jack and Jill”, two people treated as the same noun in the context of this sentence.
So in deciding whether to add the possessive to the end of the list or to each item of the list, you first need to understand whether the possession is shared by all the members of the list (the group) or belongs to the individuals that make up the list.
Alas, multiple nouns in a noun phrase is one of the areas for which “choosing whatever sounds right” doesn’t always work. It occasionally requires a bit of thought, especially for more formal English, but the good news is that the rules are pretty consistent here.