“Representation #16?18 (matchbook),” by Cynthia Greig © The artist. Courtesy Clark Gallery, Lincoln, Massachusetts

Readers of Elif Batuman’s delightful first novel, The Idiot, will need no introduction to its sequel, Either/Or (Penguin Press, $27), which shares both its pleasures and its limitations. Those as yet unfamiliar with Selin, Batuman’s Turkish-American narrator, and her comic philosophical riffs on college life, might do well to begin with The Idiot, which fully describes Selin’s world: her roommates and friends, her academic interests, and above all, her unrequited crush, Ivan.

The Idiot takes place in 1995, primarily at Harvard University, where…