A correspondent writes to ask if linguistics has anything to offer in relation to the recent Facebook paedophile scandal and all the current discussion about panic buttons.

Of course it does. Indeed, the point has already come up on this blog, when I was talking about internet applications a few years ago (March 2007). In 2003 I developed an application called Chatsafe, using a technology I call a sense engine, which carried out a linguistic analysis of a conversation in order to identify dang...