Following is an excerpt from 「涼宮ハルヒの憂鬱」. My questions concern the last sentence.
There are two points of confusion, marked in bold.
I realize that it is not used in a mathematical sense (right?), and according to this 知恵袋 post, it seems it can also mean something like "looking at the points of similarity or compromise between multiple opinions or opposing parties," but I am not sure how this definition applies here. Perhaps it just means "rational" here?
I haven't seen this construct before, but I assume it can be interpreted as "at least to the point that ..."?
I am wondering what に is doing here though. I haven't seen くらい・ぐらい used with any following particles. Is it optional?
In fact, would it be okay to replace this with just まで?
I would appreciate help understanding this phrase as well.