Both, either and neither in English: the two-of-something words, agreement traps, and Me neither

English keeps a special set of words for talking about exactly two things: both, either and neither. Learners tend to meet them one at a time, spread across months, and never see that they are a single system: the two together, one of the two, none of the two. This page puts the system in one place, then deals with the two areas where it actually causes trouble - verb agreement, and the short answers So do I and Neither do I.

One warning before the details. All three words stop working the moment a third item arrives. With three or more things, English switches to all, any and none: all of the answers, any of the roads, none of my sisters. If you remember nothing else from this page, remember that both, either and neither mean two, and only two.

The three words

Notice the nouns. Both takes a plural noun (both roads), while either and neither take a singular noun (either road, neither road). Learners who write neither roads have translated from a language where the logic runs differently; in English the noun after either and neither is always singular.

Either has a second meaning worth knowing: each of the two. There were trees on either side of the river means trees on both sides, not a choice between them. Context makes it clear, and both sides is always available if you want to be safe.

both of, either of, neither of

Before the, these, my, your or a pronoun, the three words take of:

• both of my brothers / both of them
• either of the answers / either of you
• neither of these chairs / neither of us

With both, the of is optional before a noun (both my brothers and both of my brothers are both fine) but required before a pronoun: both of them, never both them. With either and neither, the of is required in both cases.

Both also moves around the sentence in a way the other two do not:

• Both my sisters work in London.
• My sisters both work in London.
• My sisters are both doctors.
• They both called me on Sunday.

The rule for position is the same as for all: after the subject, but after be and after the first auxiliary if there is one. We have both finished, not We both have finished.

The pairs: both...and, either...or, neither...nor

Each word has a partner that joins two items inside a sentence:

• She speaks both French and Spanish.
• You can either call me or send an email.
• He neither called nor wrote.

Two things matter here. First, the two halves should match grammatically: both in the morning and in the evening, not both in the morning and the evening. English speakers break this rule all the time, but when the halves match, the sentence reads cleaner, and examiners notice.

Second, neither...nor is already negative, so the verb stays positive: He neither called nor wrote, not He didn't neither call nor wrote. One negative per idea is the English budget, and neither has already spent it.

Nor has a life of its own at the start of a follow-up negative: She can't drive. Nor can I. Note the flipped word order after it - nor can I, not nor I can. The same flip appears after neither used the same way, and it belongs to the same family as the inversions covered in inversion and word order.

The agreement trap

Here is the part that costs marks. Neither and either are singular, even when a plural noun sits right next to the verb:

• Neither of them is coming.
• Either of these answers is acceptable.
• Neither of my parents speaks German.

The temptation is enormous, because them, answers and parents are plural and they are the last thing you say before the verb. Resist it in writing. In relaxed speech, neither of them are coming is common and no native speaker will blink, but the singular is the form that is never wrong.

Both is comfortably plural everywhere: Both of them are coming. No trap.

With either...or and neither...nor joining two different subjects, the verb agrees with the nearer one:

• Neither the manager nor the players were happy.
• Neither the players nor the manager was happy.

Both sentences are correct. If the second one sounds strange to you, you are in good company - the practical fix is to put the plural subject second, so the plural verb follows naturally.

So do I, Neither do I, Me neither

Agreeing with somebody is the everyday job these words do, and it runs on the same auxiliary machinery as question tags: take the auxiliary from the other person's sentence and flip the word order.

Agreeing with a positive sentence uses so:

• I love this place. So do I.
• I'm tired. So am I.
• We've been here before. So have we.

Agreeing with a negative sentence uses neither:

• I don't like mornings. Neither do I.
• I can't swim. Neither can I.
• I wasn't ready. Neither was I.

The auxiliary must match: do answers do, can answers can, was answers was. And the order is flipped - Neither do I, never Neither I do.

In speech, there are two short forms: Me too for positive sentences and Me neither for negative ones. They are informal, universal, and they save you the auxiliary arithmetic. The one thing you cannot do is cross the wires: Me too after a negative sentence (I don't like it. Me too.) is a clear learner error. If in doubt, listen for a not, an n't, a never or a nothing in what the other person said. Any of them means your answer is neither, not too.

not...either

There is a third way to say a negative also, and it sits at the end of the sentence: I don't like it either.

• She didn't call, and he didn't call either.
• I haven't seen it. I haven't read the book either.

The pattern is: negative verb, then either at the end. It means the same as Neither did he, just without the inversion. What it replaces is too - English does not say I don't like it too. Positive sentences end in too, negative sentences end in either, and the choice is mechanical once you check the verb.

Common mistakes

Ranked by how often learners actually make them.

1. Me too after a negative. I don't eat meat. Me too. The negative answer is Me neither or Neither do I.
2. A plural verb after neither of. Neither of them are here passes in conversation but not in writing. Neither of them is here.
3. A plural noun after either or neither. Neither answers is right should be neither answer. The noun is always singular.
4. Double negative with neither...nor. He didn't neither call nor write has one negative too many. He neither called nor wrote.
5. too instead of either at the end of a negative. I don't like it too should be I don't like it either.
6. both for three or more. Both of my three sisters is impossible. Two takes both; three or more takes all.

Practice

Complete each answer or sentence. Answers are below.

1. I can't come on Friday. ___ can I.
2. ___ of my parents has ever been on a plane.
3. You can sit on ___ side of the table.
4. I loved the ending. So ___ I.
5. He doesn't smoke, and she doesn't smoke ___.

Answers: 1. Neither (matching can) 2. Neither (singular verb has) 3. either (one of the two, or each of the two) 4. did (the auxiliary matches loved) 5. either (negative sentence, so either at the end, not too)

Both, either and neither are quantity words at heart, and the rest of the family - some, any, all, none, most - is covered in quantifiers. And if the flipped word order in Neither do I interests you, the full pattern lives in inversion and word order.