1. Which is your most favourite subject in school ?
  2. What is your most favourite subject in school ?

Which one is acceptable? If both are acceptable, do they have any difference in meaning?

marked as duplicate by Andrew Leach, mplungjan, coleopterist, RegDwigнt Mar 6 '13 at 10:41

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In short, when the interrogative pronoun which is used, it is asking about something among a group of things.

Note: which can also be used as a determiner.

  • @Stanley You are welcome. If there is someone who thinks that "what" should be used all the time (since you've told me about that in the comment just now), you can tell him/her that there are scenarios when what shouldn't be used: "which of the suspects murdered him?" – Archy Will He Mar 6 '13 at 9:09
  • Thanks for your comment and insight. Sometimes it is good to have an argument. It makes us to look into things in more detail. – Stanley Mar 6 '13 at 9:11

They aren't exactly equivalent. "Which" should be used when the choice is to be made from within a defined, finite set of options, as in, "Which of these is your favourite: Math, English, or Social Studies?" "What" should be used when the answer to the question could be almost anything, and is not presupposed to come from a limited subset of all possible answers.

By the way, "most favourite" is incorrect. "Favourite" is the top (preferred) choice from within a group; there can be no comparative form of this, hence "most favourite" is simply impossible, and hence wrong. (If something is the top choice, it can't be "more" top or "most" top; it's the top choice or it isn't, and no degree of being the top is possible.)

  • 2
    I would argue that some people have more than a single favorite in some groups: they aren't willing to commit to only one because they're egalitarian, eclectic, or indecisive. Therefore, they can have gradable favorites, assuming that their cognitive category labeled "favorite" contains at least two items. We do recognize that some women are "more pregnant" than others & that some people are "deader than a door nail" & that the US Constitution's preamble says: "We the People of the United States, in Order to form a more perfect Union,..." Native speakers often utter the impossible! – user21497 Mar 6 '13 at 9:16
  • @BillFranke If one of a group of favored items is more favored, it is the favorite. "Favorite" means "most favored." And nothing can be MORE or MOST "most favored." Something is either most favored or it isn't. "Pregnant" doesn't mean "most" of anything, so it's not analogous. "Deader" is merely colorful. There are no degrees of death, so there's no "most dead," which would be the only version analogous to "favorite." "More perfect" is not analogous, either. The meaning is almost poetic; the phrase implies an attempt to achieve perfection, not an improvement upon something already perfect. – John M. Landsberg Mar 6 '13 at 9:43
  • Yes, yes, all your rebuttals are the standard dogma, all predictable & none unexpected. People say what they say & think it means what they want it to mean. Who are we to tell them that they're wrong? All one can do to rectify the abuse of language is to ensure that one uses it "properly" oneself without regard to the slapdash sputterings of the solecistic. Sigh. A world without logic is sad indeed, but a world without solecisms is impossible. – user21497 Mar 6 '13 at 10:11
  • Awfully dismissive, Bill. I thought it out; I didn't merely repeat dogma. Is it dogma to state a definition? Is it dogma to say "automobile" means "personal transportation vehicle"? It's not "dogma" to say "favorite" means "most favored;" it's simply what it means. Can you tell me it doesn't mean that? If it doesn't, what does it mean? Meanings change, and are subject to interpretation, but if we don't have shared concepts of meaning, we have no language at all. Your prior examples are all very interesting, and exhibit how we can play with meaning when we agree on the "real" meaning. – John M. Landsberg Mar 6 '13 at 10:23
  • Need to thank John who pointed out that "favourite" should not normally be used with "most". But I agree with Bill that people can be indecisive in what they like most. Just checked that on an iPhone phone book, users can enter a list of "favourite" phone entries. So, at least on a certain popular mobile phone, favourite can have more than one item – Stanley Mar 6 '13 at 19:44

Well, Chris Dwyer's answer link is sufficient for you since it states that

"Which" is more formal when asking a question that requires a choice between a number of items. You can use "What" if you want, though.

Generally speaking, you can replace the usage of "which" with "what" and be OK grammatically. It doesn't always work the other way around, however. There needs to be a context of choice.

You can use both which and what for your question since it has a context of choice.

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