The Hitchhiker's Guide to the Galaxy is, Joll writes, "stuffed full" of philosophical ideas and questions. "Why am I here? What's my purpose in life? What do I mean by who I am?" asks the sperm whale which has been brought into existence  albeit briefly  by the Infinite Improbability Drive. For Amy Kind, the plight of Douglas Adams's free-falling whale sparks a memorable meditation on the absurdity of existence both in the novels and in life. She agrees with Adams that the best way of dealing with the spectre of absurdity is "to find some way of ignoring it", a pleasingly simple solution that may involve drinking a Pan Galactic Gargle Blaster. Or even two. Among the other contributions to this very readable and mind-expanding collection are Jerry Goodenough on why robots in the future may turn out to be like Marvin the Paranoid Android (sorry Mr Spock: "pure reasoning without feeling" is a myth) and Barry Dainton's disturbingly convincing essay on how the entire universe could be a computer simulation. I blame it on the white mice.