Just knowing

Tonight as I sat down to watch my Tivo'ed Project Runway episode, Little Dog climbed into my lap for a snuggle.  He's a great snuggler and after my short trip to San Jose earlier this week, I suspect he needed a little extra mommy attention.
Part way through the show he asks a question.
"Mommy, are these people real?  Are they in real life?"
A great question from a four year old, or at least I think it is.  He's starting to separate reality from make believe and TV frequently blurs that line.
"Yes," I answer.  "These people are on the show, but they are just being who they really are.  They show is about the competition, and they're competing."
"But how do you know?" he asks.  Another good question.  And kind of harder to answer.
"Well, I know this show is about the competition and I've read about the people on the show.  They're all designers when they're not on the show," I say, hoping this will be a good enough answer.
"But have you ever seen them in real life?  Have you ever seen them for real?" he asks.
A great question.  "No, I haven't.  You're right.  I have only seen them on the show, so I'm assuming the things I read and understand about the show are true."
"So then how do you know?"  And luckily he let it drop there because I'm not sure how I could have continued to defend my position.