"Multiculturalism has run its course, and it is time to move on." So begins Jonathan Sacks' new book on the future of British society and the dangers facing liberal democracy.

Arguing that global communications have fragmented national cultures and that multiculturalism, intended to reduce social frictions, is today reinforcing them, Sacks argues for a new approach to national identity. We cannot stay with current policies that are producing a society of conflicting ghettoes and non-intersecting lives, turning religious bodies into pressure groups rather than...