When should I use "is" and when "are"?

Question

Which of these are correct?

1. All I see is iPhones.
2. All I see are iPhones.

I've seen Rihanna wrote: All I see is Signs. Some people use are like: All I see are Cliffs.

Could someone explain when to use "is" and when "are"?

Answer 1

http://www.grammarphobia.com/blog/2006/12/all-is-vs-all-are.html

According to the link above :

“All” is a two-faced word. It can be either singular (“is”) or plural (“are”). If a writer means “all of it,” she should use “is.” If she means “all of them,” she should go with “are.” So it depends on whether your contributor was thinking of the whole dish or the various things in it: “All [the soup] is returned to a simmer” or “All [the ingredients] are returned to a simmer.”

Also in this forum: https://www.englishforums.com/English/AllIsOrAllAre/zdngg/post.htm

there was an interesting comment:

Meanwhile, I'll add that "all" is sometimes used to mean "the only thing". For example:

• All I want is you.

However, even if the "only thing" actually consists of more than one thing, we frequently use the singular form of the verb . For example:

• All I want for Christmas is my two front teeth.

I would also say that don't really check songs lyrics for grammar mistakes, because they sometimes use broken English in writing the lyrics!

Hope it helps you

Answer 2

Short Answer: All I see ARE iPhones

Long Answer: The subject of your sentence is "all".

All I see is/are iPhones.

All is an indefinite pronoun, and can be both singular and plural.

For indefinite pronouns that can be singular or plural, it depends on what the indefinite pronoun refers to.

Correct: All of the people clapped their hands. (All refers to people, which is plural.)

Correct: All of the newspaper was soaked. (Here all refers to newspaper, which is singular.)

Source

However, in this case, it's clear that "All" refers to the multiple iPhones that Rihanna sees, so "All" should be used plurally.