"Who is you" – not "are"

Question

Why do we say "who are you" when talking to a single person?

---

^{Related question: "Who is speaking with each other?" Is this correct?}

Answer 1

In modern English "You" is both singular and plural but it always takes a verb form that originally marked the word as plural. This happens because of the way "to be" conjugates in modern English.

• You are for singular
• You are for plural

Examples: You are, you have, you weren't, and so on... They may all mean a single object or multiple objects.

In Early Modern English there was "thou" for the singular version of "you" and "ye" for the plural version of "you" but nowadays you will hear it mostly never.

If you wish to use "you" to speak about every single person of a group, use Each one of you, Every single one of you:

• Each one of you is going to take this exam!
• There shouldn't to be a single one of you to skip my lessons!

In English "you" can stand to refer to an unspecified person and is primarily used as a colloquial or less formal substitute for "one".

Answer 2

Because of how "to be" conjugates:

• I am - Who am I?
• You are - Who are you?
• He/She/It is - Who is he/she/it?
• We are - Who are we?
• You are - Who are you?
• They are - Who are they?

You can see that the "who" makes no difference whatsoever, "are" is simply the form of "to be" that goes with "you" (whether "you" is singular or plural).

Answer 3

Part of the reason for confusion, I think, is that English has almost, but not completely, eliminated some of the kinds of inflection that still exist in related languages such as German.

For example, the German word haben (to have) conjugates as follows:

• 1st person: ich habe (singular), wir haben (plural)
• 2nd person: du hast (singular), ihr habt (plural)
• 3rd person: er/sie/es hat (singular), sie/Sie haben (plural)

That's five different forms of the verb for just one tense. In English we have collapsed the forms down to just two:

• 1st person: I have (singular), we have (plural)
• 2nd person: you have (singular), you have (plural)
• 3rd person: he/she/it has (singular), they have (plural)

A similar pattern exists with most verbs in English: there are only two forms for the indicative present tense, two forms for the perfect tense, and for most other tenses there is only one form of the word for all six combinations of person and number.

If we count the combinations of person and number that use each form of the word to have (or almost any other verb) in the indicative present tense, the general pattern is that there is no distinction between singular and plural forms, except for the third person singular. That exception is a huge one, because practically every use of a verb that occurs with a noun (rather than a pronoun) is in the third person. But grammatically, there are not distinct "singular" and "plural" forms of verbs in English, but usually only distinct third person singular and third person plural forms in any given tense, if indeed there is any distinction at all.

The conjugation of the verb to be is a bit unusual, which may add to the confusion regarding its proper usage:

• 1st person: I am (singular), we are (plural)
• 2nd person: you are (singular), you are (plural)
• 3rd person: he/she/it is (singular), they are (plural)

Unlike the vast majority of English verbs, this one has retained a unique form for the first person singular indicative present tense. Since two of the three singular persons are exceptions here, it is even less clear than usual that they are the exceptions, rather than the second person singular.

Answer 4

I am afraid none of the answers has properly addressed OP's real confusion. How can he (or she) not know "you" conjugates with "are"??? I bet he knows. What he is not sure, is why an unknown object ("who") declines with plural "you".

The sentence "Who __ you?" is related to two different meaning. The first one is:

(A) You are X --> Who are you?
(Equivalently: What object is your nature? What identity do you possess?)

But also,

(B) X is you --> Who is you?
(C) X are you --> Who are you?
(Equivalently: What human being, thing, or whatever, is equated with your characteristic?)

(B) and (C), however, is rare. When we say (B), we usually say "Which one is you?" and there is no confusion. (C) is strange, since it is unthinkable that several person may be equated with a single person (you).

Consider a history instructor is displaying a rare photo of young George Washington, among several other boys, and asks the students:

Who is George Washington? Can you tell that in the picture?

The spirit is similar to "Who is you?" Indeed, we are asking which object, among others, equates with George Washington.

Consider the flying spaghetti monster, who can transform into everything in the world. One night, John dreams of the monster, and the monster says to him: "I visited your company today, just for fun. Among the 10 committee you met today, some were my incarnations." Shocked, John replies,

Who are you? Which ones among them are actually you?

This contrived example still seems awkward, because the situation is so strange.

Such correspondence of the subject, however, is legitimate. Compare also:

Alice: How many apples are left in the refrigerator?
Bruce: Only one. I will buy some later.

Alice supposes there are plural apples, despite not knowing that for sure, and she was wrong: there is only one.

And consider: Mary, a kid, watched a scary movie and was frightened. Now, in the dark lane she is walking with her mother, and sees a strange-shaped shadow cast long on the ground:

Mary: Mom, what is that in the shadow? Who is standing there?
[A dog barks]
Mom: Don't worry, that's just a dog.

Mary supposes there is a (single) human being in the shadow, but there, it turns out, is none.

We can say that the form "Who -- be -- X" or "What -- be -- X" may be ambiguous on which the subject is, but some can be ruled out by grammar, and some by context. I would say in daily life, "Who are you?" is safe.

That said, I am not native English either, so here is just my two cents.

Answer 5

When you supplanted thou, it was initially standard to use verb forms which matched the meaning of a sentence: you are addressed to a group, and you is addressed to a single person. This usage survives in some dialects, but has dropped out of formal usage. These days, the verb form used agrees with the word, not with the word’s meaning, so you always takes a plural verb, even when it has a singular referent. The same applies to the singular use of they.

singular                                        plural
I am                                            we are
thou art (obs.) / you is (obs.) / you are       you are
(s)he is / one is / they are                    they are