It is uncanny how many books will insist that neither 'many' nor 'much' can be used in positive sentences.
- Have you got many pens? / Have you got much money? –> correct
- I haven't got many pens. / I haven't got much money. –> correct
- I have got many pens. / I have got much money. –> INCORRECT
And yet, those same books will invariably have a text where – lo and behold – 'many' is used in a positive sentence!
I can only guess that proper grammar rules are as dictated, but every day use has drifted considerably from the said rule.
So I ask you: what is the real usage of 'many'. Has it become common in any type of sentence? Or are there situations when 'many' can be used in positive sentences and situations when it can't? Because I really don't know what to say when the students point at a text and say it isn't following the rule they are supposed to follow.
Best Answer
There are some senses of "much" and "many" that are restricted to non-affirmative contexts, and when "much" and "many" are used in that way then they are negatively-oriented polarity-sensitive items (NPIs).
There are some senses of "much" and "many" that can be used in positive affirmative environments, but then those instances of "much" and "many" are not NPIs.
And then, to make things even more confusing, some words (such as "much" and "many") may be an NPI in some styles or registers and not in others.
This issue with "much" and "many" is discussed in the 2002 CGEL, pages 823, 826-7. There might be some related info about NPIs on the internet, such as in wikipedia or on linguistics sites, but you've gotta be careful of info found on the internet.
If you want more info here in this post, then leave me a comment and I'll try to come back later tonight. (The reason why this post is now so brief is that many topics are involved and I'll have to discuss them as a foundation for this topic that you are asking about.)
Note that CGEL is the 20002 reference grammar by Huddleston and Pullum et al., The Cambridge Grammar of the English Language.