Norms about (online) debate
Behave in good faith. You and your fellow debater are not evil people. You’re not looking to destroy the world, make everyone into zombies or impoverish people. You both should be looking to argue with that assumption that the other person is arguing because they want to make the world better. This avoids name calling and general unpleasantness
Ad hominem attacks should be very very rare. When you’re arguing about something, argue about the idea, not the person you are arguing against. The only exception is when the person and the idea are the same thing.
Be polite. Even if the person whom you are debating is incredibly wrong, there are good and bad ways to phrase it. Some of these are hurtful, and some of these are less so. Some phrase it in a way that attacks the idea, and some in ways that attack the people. Wherever you argue, it is better to be polite when you can be.
Epistemic Standards
Be able to pass the ideological Turing test. This means that you should be able to state your opponent’s views in ways that they agree is a fair representation of them. This prevents both parties from debating a strawman.
Have a criterion for the burden of proof required to change your mind. For example, if you are debating about the efficacy of a certain policy, you should state what evidence would be sufficient to change your view about it. Not only does this make the lines of the debate clearer, it also makes the debate more efficient because both parties can focus on what can change the other person’s mind.