"Yes or no: was there once life on Mars?" I can't say. "What about intelligent life?"' That seems most unlikely, but again, I can't really say. The simple yes-or-no framework has no place for shadings ...

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Hey mathematicians! My name's Ms Szalek and welcome to maths. Today we're going to focus on probability ...