Which is grammatically correct: "if someone was starving" or "if someone were starving"?

Question

Which sentence is more grammatically correct:

• If someone was starving on an island
• If someone were starving on an island

Answer 1

"if someone was starving on an island"

This denotes the factual condition of whether someone was at an earlier time starving.

"if someone were starving on an island"

This denotes a hypothetical, as opposed to a factual statement about something already happened. Using "were" in this case is known as the subjunctive mood. If it's this use you're using then "were" is the correct one. This is much like saying:

"If someone happened to be starving on an island, would you help him?"

Subjunctive mood

Subjunctive forms of verbs are typically used to express various states of unreality such as wish, emotion, possibility, judgment, opinion, obligation, or action that have not yet occurred Link

Examples:
The past subjunctive
"If I were rich I would buy a Ferrari."
"I wish I were taller."
"If only he were here now!"
Collins Dictionary

Use of the past subjunctive:

"If I were your wife, I would put poison in your coffee."
Wikipedia article on English subjunctive

The subjunctive mood in other languages is more obligatory and its misuse is less acceptable. However in English using the simple past in place of where the subjunctive mood should be used is quite commonplace, especially informally. It's more strongly delineated in other languages using completely different inflections/conjugations, and in English I think it's harder to detect.

In Modern English, the subjunctive form of a verb often looks identical to the indicative form, and thus subjunctives are not a very visible grammatical feature of English.

English subjunctive