Rourke said, “It’s the oldest semantic weapon there is. Think of all the categories of people who’ve been classified as non-human , in various cultures, at various times. People from other tribes. People with other skin colors. Slaves. Women. The mentally ill. The deaf. Homosexuals. Jews. Bosnians, Croats, Serbs, Armenians, Kurds—”

I said defensively, “Don’t you think there’s a slight difference between putting someone in a gas chamber, and using the phrase rhetorically?”

“Of course. But suppose you accuse me of ‘lacking humanity.’ What does that actually mean? What am I likely to have done? Murdered someone in cold blood? Drowned a puppy? Eaten meat? Failed to be moved by Beethoven’s Fifth? Or just failed to have – or to seek – an emotional life identical to your own in every respect? Failed to share all your values and aspirations?”

I hadn’t replied. Cyclists whirred by in the dark jungle behind me; it had begun to rain, but the canopy protected us.

Rourke continued cheerfully. “The answer is: ‘any one of the above.’ Which is why it’s so fucking lazy. Questioning someone’s ‘humanity’ puts them in the company of serial killers – which saves you the trouble of having to say anything intelligent about their views. And it lays claim to some vast imaginary consensus, an outraged majority standing behind you, backing you up all the way. When you claim that Voluntary Autists are trying to rid themselves of their humanity , you’re not only defining the word as if you had some divine right to do that … you’re implying that everyone else on the planet – short of the reincarnations of Adolf Hitler and Pol Pot – agrees with you in every detail.” He spread his arms and declaimed to the trees, “ Put down that scalpel, I beseech you … in the name of all humanity! ”

I said lamely, “Okay. Maybe I should have phrased some things differently, yesterday. I didn’t set out to insult you.”

Rourke shook his head, amused. “No offense taken. It’s a battle, after all – I can hardly expect instant surrender. You’re loyal to a narrow definition of Big H – and maybe you even honestly believe that everyone else shares it. I support a broader definition. We’ll agree to disagree. And I’ll see you in the trenches.”

Narrow? I’d opened my mouth to deny the accusation, but then I hadn’t known how to defend myself. What could I have said? That I’d once made a sympathetic documentary about gender migrants? (How magnanimous.) And now I had to balance that with a frankenscience story on Voluntary Autists?

So he’d had the last word (if only in real time). He’d shaken my hand, and we’d parted.