conuly

I think one of Hermione's big problems is that she believes everything she reads in books, and thinks that anything outside her knowledge is poppycock. She has the capacity to use logic (as we saw in book #1), but over the years her head has gotten so big (constantly spoken of as 'top of her class'), that she thinks she knows everything.
I wouldn't be surprised if this egotism gets the best of her eventually.