All people are a mystery.

Since the subject is plural, should the the predicate nominative mystery be also plural? And would the meaning still be the same? As in All people are mysteries.

How about the following?

All people are a phenomenon.

All people are phenomena.

  • 2
    If you would use the plural "mysteries" you'd say that every single man is multiple mysteries. Somewhat weird, isn't it?
    – Em1
    Commented Sep 6, 2013 at 8:03
  • 3
    But in These dogs are heroes, it surely doesn't mean that every single dog is multiple heroes. This is why I'm confused. Why can't I apply the same pattern to the sentence All people are mysteries to mean that every single person is a mystery?
    – Sherlock
    Commented Sep 6, 2013 at 8:31
  • 1
    I see. I try to make it clear this way: Compare: One dog but many dogs. One person but many people. So you need the plural verb form. "All people" however is a way of referring to any individual. You can replace "All people" with "everyone" or "everybody". Then again it's obvious that you'd say "Everyone is a mystery". Ouhh - wait. "All people are heroes" is fine again, I guess this is due mystery and phenomena being more abstract than hero.
    – Em1
    Commented Sep 6, 2013 at 8:45
  • @Em1 But "Everyone's a critic" makes perfect sense, and neither critic nor hero abstract! Interesting, interesting....
    – WendiKidd
    Commented Sep 6, 2013 at 14:16
  • Won't it suit better if we say everybody is a mystery?
    – aarbee
    Commented Sep 8, 2013 at 19:40

3 Answers 3


Predicate nominative is a noun or pronoun that follows a linking verb and refers to the same person or thing as the subject of the verb.

Here, mystery is a noun that links the subject people with the verb "are".

As , verb is in agreement with the subject i.e. Subject : people, Verb: are.

So, to link the verb and subject , singular form of the predicate nominative mystery ( which is a noun form) is used.

Because ,if we use plural form then the verb and subject cannot be agreed with each other.

Basically, here noun "mystery" works as an adjective as it shows the quality of the people.

So, it's apt to use the adjective form of the word "mystery" to make it a perfect sentence.

We can write like this : All people are mysterious, All people are heroic. This sounds much better as here the nouns perform the role of the adjective.


While it may appear at first glance that the sentence is unbalanced (All -pl. are - pl. a mystery), the "mystery" is resolved when one understands that "mystery" (and even people. for that matter) can act as a collective noun.

In such a situation, what appears to be a singular noun is, in fact, acting as a plural.

To write "All people are mysteries" removes the ambiguity, and may perhaps be "more correct," but the meaning of "All people are a mystery" is not grossly ungrammatical to the native ear.


"All people are a mystery" is ungrammatical because you have a plural subject and a singular complement. One should say "people are a mystery" or "all people are mysteries" or even "every person is a mystery."

Notice the differences between these three. "People are a mystery" means that people as a whole are one big mystery. "All people are mysteries" means that the set of all people is a set of mysteries. "Every person is a mystery" means each individual person is a mystery. For the verb "to be," the last two have equivalent meaning of course.

Compare: "At this school, all boys love girls" with "At this school, every boy loves a girl." The first claims the boys are all heterosexual, but the second claims they're monogamous too.

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