Writings by conservatives and a liberal

I recommend the following books. They are insightful, provocative and delightful though a bit controversial (or call them thought-provoking.)

Grand New Party by Ross Douthat and Reihan Salam -- two conservatives (as the title of the book may make it clear) who have written about economic policy
Heads in the Sand by Matt Yglesias -- a liberal (again as the title of the book may make it evident) who has written about foreign policy