Let's say that I show you a deck of cards, unopened, and ask you if the deck contains a blue jack. You would, quite rightly, say that you have no idea, one way or t'other.

I open the package, take out the cards and proceed to shuffle them in front of you. I ask you to cut the deck, which you do. I then begin to turn up the cards from the top of the deck, one by one. The cards appear to be completely normal. There are clubs and spades, both black. There are hearts and diamonds, both red. There are numbered cards and face cards. I continue until I've turned up half the deck. All appears normal for a regular deck of 52 cards.

I again ask you if the remainder of the deck contains a blue jack. If you're answering truthfully, you would say that, thus far, the deck appears normal. I then ask if you're a little bit more certain that the deck doesn't contain a blue jack compared with before I started turning them up. Your answer: 'Perhaps a little bit more certain.'

I continue facing cards from the top of the deck until but 13 remain. Again, the cards are perfectly ordinary. I again ask, 'Are you a bit more certain now than at the halfway point that the remainder of the deck does not contain a blue jack?' Your answer is again, 'Yes'.

I now face 10 of the remaining 13 cards. I ask again about your certainty regarding a blue jack. Again, you're a bit more certain.

I now change the question and ask, 'If I turn up the next card and it is not a blue jack, will you be a bit more certain that neither of the remaining two cards is a blue jack?'. When you answer, 'Yes', I turn up the next card.

It's a green queen.

Regards, and thanks for reading. Stay safe 'n well.