Especially when you are still familiarizing yourself with a topic, it's good to do background research to identify components and subtopics of the debate. Here are a few good places to start your research:
You don't want to use a Wikipedia article as evidence, but it's a great way to find general information, and the Notes and References section can be a goldmine.
The Congressional Quarterly Researcher provides in-depth reports on controversial subjects such as gun control, health care, and obesity. The reports include a Pro/Con view, chronology of events, current situation awareness, and lists further resources. An excellent resource for a position paper.
An online version of the famous historical dictionary that traces the development of a word over time using evidence such as books, periodicals, and films.
Google Ngrams will show you a graph displaying how often a word or several words have been used in a corpus of literature (English Literature, American Literature, etc.), over a period of time.
