Some good but recently published books (I.e. Last 5 or so years) suitable for a 13 year old, with an interesting story line that could lead to discussions are:
Maggot Moon by Sally Gardner - an award winner. Dystopian past where the landing on the moon was faked by a controlling government, a slightly aspergers but very witty character,
Bog Child by Siobhan Dowd - two slices of history in Ireland - a story from the very distant past runs alongside a boy struggling with the fall out of the IRA hunger strikes. Quite topical given Jerry Adams recent arrest.
The Curious Incident of the Dog in the Night by Mark Haddon - seeing the world through the eyes of an autistic boy. Some swearing.
Out of Shadows by Jason Wallace - about Zimbabwe when Mugabe first took over. Raises some interesting discussion points
The Wall by William Sutcliffe - loads to discuss but maybe not such an enjoyable
But I really agree with the other comments that he must feel strongly about the book - either positively or not - so he can discuss it with feeling. It would help if it's made an impact on him - made him see things differently, made him read something else etc.
If you want to think about a more classic book I would look at The Outsiders by SE Hinton. It's a modern classic and really appeals to teen boys. It makes you think about how society judges us etc.
A book my 13 year old was asked to read before joining a school at 13+ was Spud by John van de Ruit. It's hilarious but also poignant and sad. It's set in a boarding school in South Africa and there are many references to politics at the time, to other books, to music of the time and so a reader can get a lot out of it.
Good luck