Open-question argument is when someone is having a conversation with someone else and brings up a topic that does not have one right answer. It's a way for people to have a discussion about different topics. For example, someone may say, "What do you think about the new movie that came out?" This is an open-question argument because there is no one right or wrong answer to this question. Everyone will have different opinions on the movie, so it's an opportunity to talk about the different views that different people have.