PEN America is a venerable organization of writers that, it says on its website, “stands at the intersection of literature and human rights to protect free expression in the United States and worldwide.” In recent years, though, it has more often stood at the intersection of political infighting and bad publicity.

The latest black eye: Dinaw Mengestu, a novelist who became PEN America’s president last December, resigned on July 9 and then, in an essay for Literary Hub, attacked “the organization’s hypocrisy,” “dishonesty” and “bigotry.” As in past PEN America controversies, the flash point was disagreement over Israel and the Palestinians. The underlying causes are the literary world’s expansive sense of its social role and confusion about what counts as a threat to free speech — and what doesn’t. . . .