ASIO head Duncan Lewis appears to have caught a nasty disease from Brandis — existentialitis. You might recall that a couple of years ago the Attorney-General began describing Islamic State as an “existential threat” to Australia , a bizarre claim, given, by its own admission, the worst it could do was launch individual attacks that might lead — and has led — to tragedies, but which hardly amount to the destruction of society.

Last night, Lewis also began using “existential” — but like a mutating virus, the usage has changed in its transmission from AG to Director-General. Lewis used it not in reference to Islamic State — sorry George —  but in relation to state-based espionage, which he declared was an “existential threat” to Australia. How spying by, say, China or Russia could amount to an “existential threat” to Australia isn’t clear — we’d have thought “existential” was something more like the possibility of being wiped out in a nuclear exchange, not theft of state or commercial secrets. It seems “existential” has joined that list of words that some of us gamely but futilely fight to retain the actual meaning of — words like “decimate”, “genocide” and “literally”.