Canvassing the craven and deviant (which is to say, left-oriented, mainstream) response to the Boston Marathon bombing among media and intellectual elites — yes, the Tsarnaev brothers killed and mutilated but they were displaced, troubled, resentful of Western domination, etc. — Bruce Bawer offers an astute diagnosis. The progressive multiculturalism to which these elites adhere, he writes, is both decadent and jejune, enabling them to remain mental and emotional children who preen themselves on their kindness. “What made multiculturalism attractive to these people,” Bawer continues, “is that it’s tailor-made for spoiled, narcissistic grown children who don’t want to have adult...