Sir Humphrey and Hacker in “The Grand Design”

Sir Humphrey

With Trident we could obliterate the whole of Eastern Europe.

Hacker

I don't want to obliterate the whole of Eastern Europe.

Sir Humphrey

But it's a deterrent.

Hacker

It's a bluff. I probably wouldn't use it.

Sir Humphrey

Yes, but they don't know that you probably wouldn't.

Hacker

They probably do.

Sir Humphrey

Yes, they probably know that you probably wouldn't. But they can't certainly know.

Hacker

They probably certainly know that I probably wouldn't.

Sir Humphrey

Yes, but even though they probably certainly know that you probably wouldn't, they don't certainly know that although you probably wouldn't, there is no probability that you certainly would!