Midway through my opening address for the Brisbane Writers Festival earlier this month, Yassmin Abdel-Magied, a Sudanese-born Australian engineer and 25-year-old memoirist, walked out. Her indignant comments about the event might have sunk into obscurity, along with my speech, had they not been republished by The Guardian. Twenty minutes in, this audience member apparently turned to her mother: “ ‘Mama, I can’t sit here,’ I said, the corners of my mouth dragging downwards. ‘I cannot legitimize this.’ ” She continued: “The faces around me blurred. As my heels thudded against the grey plastic of the flooring, harmonizing with the beat of the adrenaline pumping through my veins, my mind was blank save for one question. ‘How is this happening?’ ”

I’m asking the same thing.

Briefly, my address maintained that fiction writers should be allowed to write fiction — thus should not let concerns about “cultural appropriation” constrain our creation of characters from different backgrounds than our own. I defended fiction as a vital vehicle for empathy. If we have permission to write only about our own personal experience, there is no fiction, but only memoir. Honestly, my thesis seemed so self-evident that I’d worried the speech would be bland.

Nope — not in the topsy-turvy universe of identity politics. The festival immediately disavowed the address, though the organizers had approved the thrust of the talk in advance. A “Right of Reply” session was hastily organized. When, days later, The Guardian ran the speech, social media went ballistic. Mainstream articles followed suit. I plan on printing out The New Republic’s “Lionel Shriver Shouldn’t Write About Minorities” and taping it above my desk as a chiding reminder.

Viewing the world and the self through the prism of advantaged and disadvantaged groups, the identity-politics movement — in which behavior like huffing out of speeches and stirring up online mobs is par for the course — is an assertion of generational power. Among millennials and those coming of age behind them, the race is on to see who can be more righteous and aggrieved — who can replace the boring old civil rights generation with a spikier brand.