TWTS: "Both" and "each" are interchangeable, except when they're not.
We love it when listeners share their grammar-related conversations with us, especially the casual conversations they have with family and friends.
Bruce Sagan recently shared this conversation he had with his wife:
“I was helping my wife set the table for lunch when she told me, ‘We will both need forks,’ which she immediately corrected to the more accurate, ‘We will each need a fork,’ although I understood exactly what she meant the first time.”
This got the couple thinking about when “both” and “each” are interchangeable and when they’re not. For instance, Sagan says, “I would only say, ‘Today it’s both windy and rainy,’ but never, ‘Today it’s each windy and rainy.”
It’s nice to know that we’re not the only ones who find this to be a reasonable way to pass the time during a meal. It’s also nice to know that listeners think of us when they find themselves in this situation.
Let’s start with parts of speech. “Each” and “both” can be determiners or pronouns. When they come right before a noun, they’re determiners. When they stand alone, they’re pronouns.
In the sentence, “Each goldfish is a dollar,” “each” is a determiner. Take out “goldfish” and “each” becomes a pronoun: “Each is a dollar. This works for “both” too: “Both my fish are goldfish,” or “Both are goldfish.”
When you’re only talking about two things, “both” and “each” can be interchangeable and often are. However, “both” can sometimes be ambiguous.
If you say, “Both goldfish are a dollar,” someone could assume that one dollar gets them one goldfish. Since “both” can be and often is distributive, this is a reasonable assumption to make. However, it wouldn’t be out of the realm of possibility for someone else to assume that for one dollar, they’re getting a pair of goldfish.
On the other hand, “each” is always distributive. “Each goldfish is a dollar” clearly means one dollar gets you one goldfish, two dollars gets you two goldfish, etc.
While there are some other grammatical distinctions between how “each” and “both” work in a sentence, let’s get back to the question Bruce Sagan ran into while setting the table with his wife.
“I would say that it isn’t necessarily that ‘We each need a fork’ is more correct than ‘We both need forks,’” says Professor Anne Curzan. “‘Both’ has some ambiguity to it but, as [our listener] Bruce notes, in most contexts, ‘We both need forks’ could be read in the distributive sense — that we need two forks.”