A debate or a discussion is, for me at least, an exchange of facts, opinions, arguments, based on the shared assumption that both parts of the debate are sincere (good faith): sincerely defending their point of view, willing to to change it if need be, respecting enough the opposite part, which means listening to counter arguments. Someone lying or not willing to listen or not really defending his position is no fit for a debate, don't you agree? Or maybe you enjoy debating with trolls that after you've spent hours trying to explain your view they'll say "I was not really saying that, I was joking"?