You do, but not to win. You do it to enrich the conversation and to learn. So that's advocacy. Inquiry is what happens as a result of being genuinely curious. One way it shows up is in the way people ask each other questions about their positions, about what led them to the conclusions they hold.
People do that all the time when they argue - there's nothing special about that.
What's special is that the questions are driven by curiosity, not by a desire to prove the other wrong. Look, I can ask you a series of questions based on the assumption that you're wrong. When I do so, the questions have a quality of trying to corner your idea and kill it. But, imagine if I ask you a series of questions based on the assumption that you might be right. The questions I create will help me to understand your point of view more fully.