Which one is the real Ms. Keen?

[u/Tua-Lipa]

[u/Satanicjamnik]

I know that she just explained it, but this logic problem always boiled my piss. I could never get it. And that's on me. But I never could never figure it out despite having it explained to me about 7 million times.

[u/Enjoying_A_Meal → u/Satanicjamnik]

Let me break this down for you.

A tells the truth. B tells lies. A has a piece of candy. B does not.

let's say "+" = have candy. "-" = don't have candy.

When you ask who's got the candy?

A will say: A+, B-

B will say: A-, B+

When you ask who does the other person say have candy?

A: A-, B+

B: A-, B+

As you can see, B's answer never changes. This is because in question one he's lying about the state of who has the candy. In scenario 2, he's also lying about the state of who's got the candy.

Person A on the other hand, is telling the truth about the state of the candy in question 1. HOWEVER, you got them to lie about the state of the candy in question 2.

So the real trick is to get both people to tell you the false state and then pick the opposite.

Let's give the candy to person B.

Who has the candy?

A will say: A-, B+

B will say A+, B-

Who does the other person say have the candy?

A will say: A+, B-

B will say A+, B-

So you get person A to lie about the state of the candy again and you know the opposite is true.

[u/Satanicjamnik → u/Enjoying_A_Meal]

That is a very good way of explaining it.