Which or what - when? Would one of you please clarify?

[yogabird]

Which book/dress/whatever would you like?
What colour? Which colour?
When should each of these be used, o wise ones?

[Janni]

I was thinking something along those lines too. 'Which' would be for a limited choice of items.

[yogabird]

Would that be 'What wine would you like, madam?' when offered an extensive wine list, do you think? Or does that sound wrong? I like your idea Janni/Jura but still not quite sure. Anyone want to add to this?

[yogabird]

'what books couldn't you put down?' Is it right or should it be which? Seems to me that 'which' sounds better.

[squeaver]

I think (and I'm sure Sheik or someone else will provide a definitive answer here) "which" is for a limited number. It may even be when the choice is between two items.

Quite interested in knowing the answer now.

[fridayschild]

I'm with Jura. "What wine, modom?" is just wrong, wrong, wrong.

[yogabird]

anyone else? at all?

[PortAndLemon]

BBC World Service dodges the question:

When there are only two or three possibilities to choose from, which is normally preferred.

When there are an unlimited number of choices, what is used.

Compare the following:

• Which biscuits do you want me to buy ? milk chocolate or plain chocolate?
  I?d like the milk chocolate ones, please.
  
  
• What kind of work do you do?
  I work as a lawyer for a firm in the city.
  
  ... all of which leaves undetermined the question of the correct word if there are four or five (or forty, fifty, four hundred or five hundred) choices.

[PortAndLemon]

If you're really keen...

Aarts, Bas (2002, with Evelien Keizer, Mariangela Spinillo and Sean Wallis) Which or what? A study of interrogative determiners in present-day English. In: Andrew Wilson, Paul Rayson and Anthony McEnery (eds.). Corpus Linguistics by the Lune. (Lodz Studies in Language series). Frankfurt am Main: Peter Lang.

[PortAndLemon]

This explanation seems better -- what if the possibilities are either unlimited or of unknown numer, and which if there is a specific, known, number of options (which will normally imply a fairly small number of options).

[PortAndLemon]

(In the case of the wine list, I think which is correct; brandishing the wine list equates to there being a specific, known, number of options even if you haven't actually counted them)

[yogabird]

interrogative determiners - wow! I had no idea i was opening such a can of worms. THanks Port & Lemon - very thorough. Oooh! Just thought, 'What Car' magazine. 'Which' the consumer magazine, does that inspire any further thoughts?