Not so long ago, it was decidedly taboo to speak badly about Jews. Today, from tenured professors at major universities to mobs trying to burn down synagogues in Paris, people openly speak and write — sometimes cautiously, sometimes not — about the presumed malevolent power of Jews. Sometimes they carefully denounce “Zionists,” but open Jew-hatred is now commonplace, and the Jew-haters are getting a hearing.

It’s important to understand how we get from there to here, from a near-universal taboo against anti-Jewish remarks to toleration of nasty anti-Jewish incitement. And there’s no one who has provided as good a guide to that grim journey than Ben Cohen. It’s in his recent book, Some of My Best Friends.

Dramatic changes of this sort don’t happen quickly. Cultural paradigms — embodied in standards of “good manners” — change slowly, and it has taken several generations for antisemitic language to slither back into permissible discourse. One of the many great things about Ben Cohen’s book, which is a collection of his essays over the past several years — is his keen eye for the little watersheds along the way. Bit by bit, small event after small event, we got there. Kudos to Mr. Cohen for noticing them and doing the hard and depressing work of chronicling them.

These little events range from British court decisions to parliamentary debates, to administrative decisions at major and minor universities. Mr. Cohen writes with admirable restraint about the now-forgotten case of Ronnie Fraser, “an unassuming lecturer in mathematics at one of London’s further educational colleges,” who brought a court case against advocates of an academic boycott against Israeli academics and their institutions. He lost his case, thereby, as Mr. Cohen says, “(leaving) the definition of what constitutes antisemitism to (often hostile) non-Jews.” He quotes Fraser in a very important post-verdict statement:

For the court to say that, as Jews, we do not have an attachment to Israel is disappointing, considering we have been yearning for Israel for 2000 years and it has been in our prayers all that time.

Mr. Cohen warned at the time (2012) that the British decision would create a dangerous precedent, to whit that whenever Jews say that antisemitism is a major component of anti-Zionism, they are arguing in bad faith.