Bad faith argumentation or debate is the act of trying to win an argument regardless of the veracity of ones position. In principle, disagreements occur over difference in peoples perceptions of reality. I saw one thing you saw another and we go back and forth trying to understand what the other person thinks and why. Debate is just supposed to be a more structured version of the same process. But what is meant as the search for truth and understanding often goes wrong. People get frustrated, they are too proud to concede a point, or they never really cared about the truth and it shows in the way they argue. Fallacies crop up, attacks become personal, and the tone changes from an exchange to a conflict.

An example: Alice thinks widgets are a good investment but Bob thinks they're a bad investment. Alice points out that the value of widgets has been rising for the past five months but Bob responds that widgets are ill defined items mostly only useful in thought experiments about economics with no practical value so their present market price is almost certainly an economic bubble ready to pop. This is a good point and Alice has to seriously consider what Bob is saying. It could be a bubble that's on the verge of destroying the economy and that would be the sort of investment Alice wants to avoid. She mentions that she might just invest briefly and try to get out before things go south. Bob then says widgets also hurt the environment. Alice concedes that that may be true but she's just trying to decide if it's a good investment. Bob mentions that his cousin choked to death on a widget and why would anybody take their side. At this point Alice decides that Bob isn't really arguing against investing in widgets so much as he just hates them for some reason. Bob comes up with a hundred other reasons why widgets are the devil's tools and even a few reasons why not to invest in them but Alice has stop listening. She thinks he's arguing in BAD FAITH.

The phrase bad faith implies a willful component to the act. This is complicated by how very good humans are at self deception and motivated thinking. Is a person who knows their arguments are shaky but sincerely believes in the conclusion they are pushing for acting in bad faith? Bad faith argumentation is probably better seen as a spectrum than a binary with a dividing line where it's no longer worth trying to engage with the interlocutor.