Using で instead of に with いる


The example sentence in [Why is も used instead of が in the sentence
「日本ではクモを見ると良いことがあると言う人もいますよ」](https://japanese.stackexchange.com/questions/8214/why-
is-%e3%82%82-used-instead-of-%e3%81%8c-in-the-
sentence-%e3%80%8c%e6%97%a5%e6%9c%ac%e3%81%a7%e3%81%af%e3%82%af%e3%83%a2%e3%82%92%e8%a6%8b%e3%82%8b%e3%81%a8%e8%89%af%e3%81%84%e3%81%93%e3%81%a8%e3%81%8c%e3%81%82%e3%82%8b%e3%81%a8%e8%a8%80%e3%81%86%e4%ba%ba%e3%82%82%e3%81%84%e3%81%be%e3%81%99%e3%82%88%e3%80%8d),

> 日本ではクモを見ると良いことがあると言う人もいますよ

got me thinking "Why is it using で, not に?". I.e., why not

> 日本には、クモを見ると良いことがあると言う人もいますよ

It seems obvious that 日本では is intended to modify います. If it were modifying 言う,
the meaning would be roughly "There are people who - when in Japan - say that
...".

Although I would personally use に in this sentence, it doesn't sound
completely ungrammatical to me as it is. So why is that, given that いる usually
takes に, not で?




では is not modifying います or 言う. That is just one of the definitions of では:
`「...の場所で」`; for/at a place.

> 京都ではもう春だ。 → It's already spring in Kyoto.

`日本では` is just setting the stage for the rest of the sentence; "In Japan", and
then leave it at that. The rest of the sentence doesn't relate grammatically
to it at all. It's not indicating the location where people talk about the
spiders. And you don't indicate where someone exists with で (see my answer
[here](https://japanese.stackexchange.com/a/105/78) for details on that).

