How to beat a Cardassian interrogator:

Cardassian: How many lights do you see?

Human female: (squints) Ummm, four, I think.

Cardassian: (slyly) Count again. Don't you mean five?

Human female: (squints again puzzledly) No, I don't think so. Just four. Is there one behind me or something?

Cardassian: (disconcerted) No, it's in front of you. Look again. How many lights are there?

Human female: (more and more confused) But I still only see four. Are you sure? Maybe you should point the other one out to me?

Cardassian: (a little irritated) Just look and tell me there are five lights.

Human female: Okay, I guess I'll just have to trust your judgment. I mean, I only see four, but my eyesight isn't the best lately. You're probably right.

Cardassian: (heavy sigh) You're missing the point.

Human female: I think I am. Why is it so important how many lights there are?

Cardassian: (ignoring the remark) There are only four lights.

Human female: (still confused) Oh, okay. So, then, I was right.

Cardassian: Yes – err, no. You're supposed to say there are five lights.

Human female: (rubs forehead) But you just said… I'm confused.

Cardassian: (leans forward with a menacing insinuation) You can only see four lights – but you have to say there are five.

Human female: (considers this for a minute) Did I hear you right?

Cardassian: (waiting impatiently for meaning to sink in) Yes.

Human female: Are you sure? I mean, you can't know what I thought you said. You might think you know what I thought you said, but you can't really know that I know what you know you said.

Cardassian: (looks slightly dazed)

Human female: (politely) Could you just repeat it one more time, please?

Cardassian: (sighs, gathers strength and leans forward even more menacingly) You can only see four lights – but I want you to tell me there are five.

Human female: (face suddenly lights up in understanding. Cardassian looks up hopefully, then slumps back dejectedly as bright smile spreads over her face.) Oh, I get what's so important! One of the light bulbs is out and you need me to change it! I love riddles! I'll have to remember that one.

Cardassian: (defeated) Guards! Release her. (under his breath) They couldn't have told her anything of importance, anyway.

The End!

PS – Honestly, for the first few minutes of that scene in Chain of Command, I thought Picard had actually counted wrong. I'm blond sometimes.