Which of these sentences is correct, and why?

  1. "What if the Moon was a Disco ball?" or

  2. "What if the Moon were a Disco ball?"

  • 2
    Just a thought, but you may want to give more people time to respond before accepting an answer. If there were others with thoughts, having an answer marked would discourage them from replying.
    – James King
    Apr 26, 2017 at 15:50
  • Similar question on EL&U When to use “If I was” vs. “If I were”
    – Mari-Lou A
    Apr 27, 2017 at 19:57

5 Answers 5


We use the preterite (past tense form) when expressing a counterfactuality.

  • If she loved me, I would change my job (but she doesn't love me).

But when it's a form of the verb to be, we can use "were" in place of it.

  • What if the Moon was/were a Disco ball (but it's not).

This form is known as irrealis were. It isn't used for marking tense; it's a mood form indicating that it conveys a degree of remoteness from factuality.

The choice between were and was is a matter of style: were is somewhat more formal than was.

Huddleston and Pullum, A Student's Introduction to English Grammar

  • 3
    This is absolutely wrong about formal and informal. "Was" is ungrammatical English. But unfortunately it's casually used by speakers so it's accepted in informal English. Apr 26, 2017 at 15:19
  • 6
    @SovereignSun I'm afraid NO! "The use of were after if he/she/it is now a matter of formality of style rather than grammar." - Pam Peter, Cambridge Guide to English Usage. Apr 26, 2017 at 15:25
  • 3
    @JamesKing Disagreed, it depends on the register, context and circumstance. Saying "If I were.." in a casual conversation is just odd and awkward. Apr 26, 2017 at 16:09
  • 7
    This is a case where modern usage has changed what is grammatical. No grammar checker and probably no English teacher in 2017 is going to mark "I wish I was" as ungrammatical, but 100 years ago it would have been more widely considered poor grammar. If it be true that "was" be ungrammatical in the conditional construction, then "is" would be ungrammatical also. The use of "is" and "was" for the subjunctive/conditional is so widespread in speech, literature, song, journalism, and everywhere else that either we call the whole English speaking world ungrammatical or we accept new usage. Apr 26, 2017 at 18:14
  • 2
    They've actually been in competition for hundreds of years. There are a few fixed phrases where were is either more likely (if I were) or strictly required, as with initial inversion, but for the most part was is a very well-established alternative with this meaning.
    – user230
    Apr 27, 2017 at 16:12

Use were (instead of was) in statements that are contrary to fact.

In your sentences it should definitely be:

  • "What if the Moon were a Disco ball" - It's not true, that's why we use the subjunctive, it's contrary to fact.

"If + were" expresses the subjunctive mood, which refers to wishes and desires and is known as a "non-factual" mood.

If you're mentioning a possibility or a probability, a chance that something could be, use "was". Also, if the condition is in line with the facts, use "was".

  • "What if it was raining yesterday in the morning?" - There's a possibility that it really was raining yesterday.

However, was has become so prevalent that it's worth considering that it may become officially accepted at some point. It's not incorrect to use "was" instead of "were" in casual English, however, strictly grammatically it is incorrect. It's one of those cases like "who to follow" instead of "whom to follow" where the former has become casually used and so common even though it's not grammatically correct.

  • 4
    I can't see any semantic difference between were and was here. I would say it's an issue of style. And if you say who is grammatically incorrect, I would argue the toss. There fair number of grammar books that says who is acceptable. It actually depends on the register and context. Apr 26, 2017 at 14:25
  • 1
    "Who" is considered to be grammatically incorrect, however, casually accepted and used. And "was" is definitely grammatically incorrect with the OP's sentence, however, casually accepted and used. Apr 26, 2017 at 14:33
  • 4
    "Was" is not merely casually accepted and used, it's near universally accepted and used. If modern novels, The New York Times, The Washington Post, NPR, countless popular songs, and virtually everyone in everyday speech are all using the same word in a particular construction, then we have little choice but to accept that word choice as common usage. I can't remember the last time I heard "were" used this way outside of myself and my immediate family members. Apr 26, 2017 at 18:18
  • 4
    In the USA, literally almost no one who is a native speaker says or writes "were" for this construction, whether casual or "formal" (sometimes it seems like there is no such thing as "formal" English in the USA). I notice that many of the people commenting and answering that "was" is only used in casual contexts may not be native speakers of American English, so they might have been taught that "were" is more correct. In many schools in the USA, we are not even taught English grammar. I was taught essentially no grammar in school and learned from my parents and Latin class. Apr 26, 2017 at 21:05
  • 1
    @ToddWilcox Therefore, I still disagree most wholeheartedly with your comment, and find it very strange that you cannot remember when you last encountered the mood's proper use, as you say, outside your own family. Because the last time I did was on Reddit, this afternoon. Do you read fiction, I wonder?
    – Kallaste
    Sep 12, 2019 at 5:11

"Was" is about the past. As in "What if the moon would have been a disco ball since forever?"

"Were" is about the future. As in "What if the moon would be a disco ball starting now?"

  • Everything you have stated here is blatantly incorrect. First, was and were are not about past and future in this case. Second, both your example sentences: "What if the moon would be a disco ball starting now?" and "What if the moon would have been a disco ball since forever?" are totally ungrammatical to the point where I can tell you are not a native speaker. In English, one cannot say "what if [something] would be" or "what if [something] would have been." Not Ever.
    – Kallaste
    Jul 6, 2019 at 2:39
  • Correct sentences in this case would be "what if the moon had been a disco ball since forever," and "what if the moon were/was(which is incorrect but still used)/could be a disco ball starting now." Not "would be." Not only is it wrong, but it doesn't even have any real meaning in this context, and is totally confusing in terms of what you are trying to say.
    – Kallaste
    Jul 6, 2019 at 2:54

If + subject + (be)..may be equally followed by the Simple Past "was" or "were". Only when you want to give advice, "were" is preferred. e.g. IF I WERE YOU, I WOULD TELL HER THE TRUTH.


You use "were". Conditional statements that are contrary to fact take the past subjunctive form in the protasis of the if-then clause. All past subjunctive forms in Modern English are equivalent to their past indicative forms except the verb "to be", which takes "were" in all persons, whether they be singular or plural (present subjunctive "they be"). It is true that in informal English, one will hear "was" said in situations like the one above wherein "were" is grammatically correct although it is often not spoken anymore. This is like the rule "It is I" versus "It's me". It's very formal bordering on humorous and thespian to say "It is I" when everyone says "It's me", but one should never write "It's me" in an English paper. It's a big no-no. So here are some examples of the subjunctive:

"What if the Moon were a disco ball?" ("were" is past subjunctive of "to be") "What if the Moon talked?" ("talked" is past subjunctive of "to talk") "What if I blew the Moon up?" ("blew" is the past subjunctive of "to blow") "If this be treason, make the most of it!" (Patrick Henry's "Treason Speech" to the House of Burgesses in Virginia, May 29, 1765; "be" is the present subjunctive of "to be" in this example.)

  • Were is sometimes not spoken anymore. Not "often." Many speakers of proper English--myself included--use were all the time in this manner. Since this is a forum discussing grammar, I would argue that we should encourage the correct usage and not overstate linguistic trends. In fact, I am sitting here reading an anthology of fiction at the moment and have literally counted the times I have seen were used for the subjunctive in the past hour: 15 times. Not one was. So yes, it is still used, and often.
    – Kallaste
    Jul 6, 2019 at 2:39

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .