My husband and I make kids defend their positions. They have lots of opinions (especially in my husband's family). If they air their opinions, we ask how they came to the conclusion and probe how well they understand the entire position and the opposite side (if we know the topic reasonably well). Actually husband's whole male section of the family (and some females) enjoy this game. It makes for fun (sometimes not so fun depending on the person) ways to get kids to think things thru. If you play nicely, they will work hard to win "the argument".