Think of the debate around your topic like you're walking into the middle of a conversation at a party. The conversation has been going on for a while by the time you get there. At this point in your research, you are listening to the ongoing conversation around your topic so that you can enter the conversation in an informed way later on. This video from the University of Nevada Las Vegas Libraries illustrates this point well:
Research is a Conversation from UNLV Libraries on Vimeo.