Well this entire sub-forum died a month ago.
You need two people to debate- that is- only two users can post to the thread.
An incentive is needed- points. Those points we all have... propose a debate and throw say, 1000 points to the winner. Find someone willing to take you up and they throw in 1000 points. Your OP would be "Taxation is theft- 1000 points to winner".
Let them debate until a moderator steps in and ends it. Then you start a poll thread to see who won the popular vote. The winner gets the points.
Problem I see here is that everything is turning into threads with one person's assertions and 20 people coming at him against him- that's not how a debate works.