An important rule in English grammar is "subject-verb agreement". It basically states that a verb must conform to the form of the noun (i.e. Singular/Plural). My question is:

What is the purpose of this rule?

It doesn't seem to play a huge role in semantics at all. "He drinks coffee" and "He drink coffee" both make sense and the -s at the end doesn't seem to add to the meaning of the sentence at all

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    It's generally pretty futile to ask for "purpose", as if languages were designed. This particular usage is the historical remnant of a time when there were distinct English verbforms for sg1, sg2, sg3 and pl; most of these slipped away gradually. Commented Dec 23, 2016 at 16:16
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    "The sheep drink(s) coffee."
    – Greg Lee
    Commented Dec 23, 2016 at 16:18
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    as others have noted, grammatical forms do not have a "purpose" in the sense of a teleology. but they do have a function, and it's reasonable to ask about the function (purpose) of 's' in "he drinks coffee". it seems we could get along fine without it, but we have retained it. why?
    – mobileink
    Commented Dec 28, 2016 at 22:04
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    iow, just because something is convention does not mean it is arbitrary or capricious. it became a convention for a reason - it served some purpose. think evolution. it's blind - no "purposes" there - but that does not mean there is no reason. quite the opposite, features survive for a reason, they satisfy some need.
    – mobileink
    Commented Dec 28, 2016 at 22:08
  • Not the reason though but an interesting aftereffect in Sanskrit is that you can arrange the words in any order in a sentence and iti wil still mean the same. 'We love XMas' 'Love XMas We' "XMas we Love'
    – ARi
    Commented Jan 5, 2017 at 16:38

3 Answers 3


Grammatical facts aren't volitional and purposive, they are conventional: you say "He runs", "I run" because that's how your colleagues and your ancestors talk(ed). If you go far enough back in time you would also say "you runst" and "we runneth". You can be understood if you say "He run", and some people do that and we don't even notice. Eventually we might all end up saying "he run".

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    That makes sense. Now that I think about it, assuming that grammatical rules need to have a purpose is strange because we didn't intentionally design them to convey perfect meaning(Credits to you and StoneyB for making me realize this) Commented Dec 23, 2016 at 16:29
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    Thou run'st, he runneth, and we/ye/they runnen (if you go back say 600 years) - otherwise +1 Commented Dec 23, 2016 at 17:29
  • @StoneyBonhiatus actually, that depends on dialect, in some, the third person singular ending was 's' and the plural was 'eth' or 'ath'. Commented May 28, 2021 at 11:08

That is for historical reasons, and it dates back millenia to those times when the ancient Indo-European languages were pro-drop, that is they tended not to use personal pronouns as subjects, many are still like that, for example Polish.

Some examples from Latin: te amo means "I love you" (lit. "you I-love"), but te amamus means "we love you" (lit. "you we-love"). As you can see, there are no subject pronouns in those sentences, still the verb form clearly shows what is meant.

All the modern Indo-European languages, including English, stem from a pro-drop ancient ancestor language, the use of personal pronouns as subjects is a later innovation, and some modern IE languages lost the subject-verb agreement completely, like Swedish or Afrikaans.


I disagree with "StoneyB on hiatus". Everything has a reason. It so happens that the reason is no longer relevant, but the rule is preserved according to tradition. However, still, the reason originally was.

In the past, there were grammatical cases in English, but now they have almost completely disappeared. In languages ​​that have cases, they show what function a word performs in a sentence. For example, you can understand who is acting towards whom. Thanks to the cases, the word order can be free, unlike in English. But if you ask a native speaker, what is the purpose of the cases, he may also say that this is just such a rule, because he has never thought about the reasons.

English cases are no longer used because they are no longer needed. Everything that has survived is probably used for something.

"mobileink" made a good comparison with evolution. If we consider the human body as a result of evolution, it was not specially designed. However, there is nothing superfluous in it. In the past, it was believed that some parts or organs were no longer needed and, for example, could be cut out. And then it turned out that they did have a function.

If an agreement exists, it most likely serves some function. The function of such things is usually to provide information that is necessary for a correct understanding of a sentence.

Yellow Sky gave a good answer.

StoneyB on hiatus said:

Thou run'st, he runneth, and we/ye/they runnen (if you go back say 600 years)

There are no longer so many agreements. But since some remained, perhaps they are necessary for something and have some purpose. What is not needed is gone, what is needed is left.

Interestingly, English is still partly a pro-drop language.

English is not a pro-drop language. Nonetheless, subject pronouns are almost always dropped in imperative sentences (e.g., Come here), with the subject "you" understood or communicated non-verbally. Wikipedia

For example, the imperative sentences have no subject pronoun:

Marry me.
Pass the salt.
Move out of my way!
Shut the front door.
Find my leather jacket.
Be there at five.
Clean your room.
Use oil in the pan. (Instruction)
Stop feeding the dog from the table. (Request or demand)
The examples are taken from yourdictionary.com

"You" are implied, but not said.

Could it be that since the verb does not change, but looks like in the present simple tense with "you", it is clear that there is an appeal to the second person?

I cannot understand if imperative sentences have any tense. But if we consider "Pass the salt" in the present simple tense it will be:

I pass the salt.
You pass the salt.
He passes the salt.

It is possible that the verb's change in the third person still exists so that there is no confusion whom imperative sentences are addressed to?

There can be no confusion with the first person because a person cannot address himself. There can only be confusion with a third person.

Thus, it is unambiguously clear that when an imperative sentence without a subject pronoun is used, the appeal is to "you", and not to someone else. That it is "you" who should pass the salt, and not someone else. Misunderstandings are ruled out since there is no "-es".

This is not all.

In informal speech, the pronominal subject is sometimes dropped. This ellipsis has been called "conversational deletion" and "left-edge deletion",[12][13][14] and is common in informal spoken English as well as certain registers of written English, notably diaries.[15] Most commonly, it is the first person singular subject which is dropped.[16]

Let's take a look at examples of the conversational deletion from learnenglishwithdemi.wordpress.com:

Gotta go now. (I gotta go now.)
See you later. (I’ll see you later.)
Got a minute? (Have you got a minute?)
Mind if I sit here? (Do you mind if I sit here?)
See what I mean? (Do you see what I mean?)
Wanna ride? (Do you want a ride?)
Hope this lesson … (I hope this lesson …)
Got any questions? (Have you got any questions?)

A little more of Wikipedia:

In speech, when pronouns are not dropped, they are more often reduced than other words in an utterance.

Relative pronouns, provided they are not the subject, are often dropped in short restrictive clauses: That's the man [whom] I saw.

As a conclusion from all that has been said:

In my opinion, the remaining Subject-Verb agreement in English can serve for avoiding confusion/misunderstanding and restoring the subject in the addressee's mind, if the subject has been omitted. It's like backing up the subject data in a verb.

  • @Yellow Sky Please read my answer.
    – Eagle
    Commented May 28, 2021 at 0:23
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    The trouble with this answer is that nearly all the examples you provide as arguments work just as well – and almost identically – in closely languages that have completely lost agreement and don’t have it at all, like Danish and Swedish. They also, of course, work just fine in those varieties of English that have lost agreement entirely. Lects like AAVE, which has no agreement in the third person singular, do just fine without it. Survival of a feature does not mean that the feature is used for anything – nor does being used for something guarantee survival (cf. the subjunctive). Commented May 28, 2021 at 13:18
  • @Janus Bahs Jacquet "Lects like AAVE" What does it mean? Please decipher.
    – Eagle
    Commented May 28, 2021 at 13:34
  • A lect is an umbrella term for a dialect, ethnolect, sociolect, regiolect, etc. – anything that ends in -lect. AAVE is African-American Vernacular English. Commented May 28, 2021 at 13:36
  • @Janus Bahs Jacquet "(cf. the subjunctive)" Could you tell about this in more detail and with an example? Or could you give a link where I can read about it, it's interesting to me? Regarding other languages, I do not know as many languages as you, so it is difficult for me to compare.
    – Eagle
    Commented May 28, 2021 at 13:44

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