Books on certain subjects, such as creationism, conspiracy theories and new-age archaeology, spawn torrents of argumentative comments.

ECONOMIST: Amateurs on Amazon

Not everybody is going to catch on in certain subjects as easily as others.

WHITEHOUSE: The President��s Back to School Speech

Last September the then Education Secretary Charles Clarke said he wanted a "national debate" on whether certain key subjects should be protected in the national interest.

BBC: NEWS | UK | Education | Big fall in university languages