Kevin Drum asks:

Specifically, if you could recommend only one book to the world, what would it be? This is not a "desert island" question, where you're picking a book for yourself, it's the single book you would most highly recommend to, say, the entire readership of this blog.

One person in the comments there recommended Richard Dawkins' The Blind Watchmaker. I'd have to second that. I think the idea of nonintentional design is probably the most important least understood concept in modern thought.

Anyway, I'm interested to see what others here would choose.