A great place to start for opposing views on many topics is Gale in Context: Opposing Viewpoints
Use search words such as "stem cells" and be sure to scan the excellent topic overview at the top of the page. Below the summary you will see headings such as Viewpoints (pro and cons of topics), Academic Journals, Primary Sources (first hand accounts), Statistics, Images, Videos, News, Magazines and more.
If you need more ideas about how to get started, try the Controversial Issues Subject Guide and the Point of View in Periodicals Guide.
