Drawing by Calvi, CC BY-SA 4.0, via Wikimedia Commons.

Dear Dr. Boli: The other day I heard one of our borough councilpeople interviewed on the radio about something—I kind of missed the subject, but I think he was talking about either a cellular mast or a petting zoo—and he was saying that whatever it was was an “existential threat” to our borough. I was trying to figure out what he meant, but I couldn’t work out the meaning of the words. What does “existential threat” mean? —Sin­cerely, A Resident of Grant Borough, Third Ward, but the Good Part of the Third Ward.

Dear Sir or Madam: “Existential threat” means that Jean-Paul Sartre left a note in your mailbox saying he would put a brick through your window. This is how philosophical debates usually progress among the Exis­ten­tialists. Ignore him and he’ll go away.