Every year the Edge Foundation asks a question
of a selection of eminent intellectuals. In 2005 the question was 'What do you believe is true even though you cannot prove it', and this book lists the answers that were given. This gives them the opportunity to discuss those ideas which are important but haven't quite reached the stage of general acceptance. However, the replies are short - often less than a page - which doesn't give much of an opportunity to explain the details of the concepts mentioned. But it does make it easy to read, so it's just the sort of book to dip into at odd moments.
The book does get a bit samey after a while, when you get to the nth contributor telling you their ideas about the nature of consciousness, and it would certainly be better to have fewer but longer articles on the ideas which are on the borderline of acceptance. The cynic in me says that to some extent this book is an advertisement for the books which the contributors have written, although actually that isn't so bad - its useful to be able to get an idea of how authors think in order to decide whether to read more of their works.