Is it "Whose fault is that?" OR "Who's fault is that?"?

Question

I wrote:

I read nearly all the contents of the websites about the war between the Nazi and Russian armies. I don't know who's fault was that! Hitler or Stalin?

• Was it whose fault or who's fault?
• What is the construction and grammar of each?

Answer 1

I don't know who's/whose fault was that! Hitler or Stalin?

First off, you need the possessive pronoun of who in front of the noun fault; that's whose, not who's. Who's is the contraction of who is or who has.

Second, the sentence is not in the interrogative. So there should be no sign of interrogation (?). The sentence should be rewritten as follows:

I don't know whose fault that was, Hitler's or Stalin's.

Answer 2

The primary thing to know here is that:

1. Who's is a contraction for "who is" or "who has" (mostly followed by "got")
2. Whose is a possessive pronoun.

So, to understand, that's what you get with each:

1. Who's fault? - Who is fault?
2. Whose fault? - Fault of which person?

Answer 3

I believe it should be whose fault that was, and also Hitler's or Stalin's?

Answer 4

Where did the OP read this comment? Users should always cite their sources.

These type of spelling mistakes are very very common, especially in social media. I call this example a spelling error rather than a grammatical one because "whose" and "who's" are pronounced identically.

The unknown author of the unverified sentence should have spelt (spelled if you're an American speaker) it whose. By the way, the punctuation is also a bit off, but let's presume the author says "Hitler or Stalin?" with the intonation rising as if he were asking the full question, "Was it Hitler's or Stalin's [fault]?".

If we write the full form we get the following

1. I don't know who has fault was that! Hitler or Stalin? (NO)
2. I don't know who is [who's] fault was that! Hitler or Stalin? (NO)

Both are very ungrammatical. No.1 makes no sense whatsoever. The auxiliary have should be in the simple past or past perfect, e.g. "I don't know who had (had) the most fault. Hitler or Stalin?

No.2 is also grammatical, the first auxiliary should not be in the present tense as if the dictators were still leading their countries today. Note the second auxiliary that follows (was) is in the past tense, so in the same sentence we have an "is" and a "was". The only way to make that sentence grammatical would be to add the preposition at between the auxiliary verb and the noun fault and modify the predicate

I don't know who was at fault there. Hitler or Stalin? (YES)

In brief, the correct spelling is the determiner whose, that means “of whom or which (used to indicate that the following noun belongs to or is associated with the person or thing mentioned in the previous clause).” adding the possessive apostrophe to the proper nouns: Hitler and Stalin would be advisable in my opinion, but not strictly necessary.

I don't know whose fault that was. {Was it} Hitler's or Stalin's? (YES)