"I have tried for much of my life to write as if I was composing my sentences to be read posthumously,” Christopher Hitchens wrote. Of course, he meant this less than literally. It was advice he used to bring himself to take the fearless positions he knew would bring on yet another firestorm. “One should compose as if the usual constraints — of fashion, commerce, self-censorship, public and, perhaps especially, intellectual opinion — did not operate.” And so he did, whether that meant ironically asserting that women aren’t funny or seriously asserting that former President Bill Clinton is likely a rapist. Seven years after he died in December 2011 — too late for obituary and too early for biography proper — we can now begin to examine his work on his own terms. Where does...