Debates are useless unless all the participants can be objective about the topic, which almost is never the case especially if there is an audience watching. Once you start a debate, then the objective is to win and everything else loses focus. To defend your side, you need conviction that you are right and in doing so, you close yourself to being educated to anything that contradicts it. You don’t change anyone else’s opinion and nobody else changes yours either. The only chance for a debate to have an educational effect is if you defend the side which you are against. The only person you can hope to educate is yourself.