The underlying causes of social ills such as violence and substance abuse are difficult to pinpoint with any certainty -- although many people have ideas about what they might be and how we might fix them. Exploring some potential causes of social challenges is a great approach to an argumentative presentation. Take a stance on which are the most pressing, why, and make an argument about where they came from and how they might be remedied.
Rights, in theory, might seem like a simple and noncontroversial topic for some -- after all, don't people agree that everyone should have equal rights? -- but the practical application of the principle of equal rights is controversial. An argumentative presentation on this topic could look at issues such as same-sex marriage, a formal equal rights amendment for women's rights, global human rights and their enforcement and the question of where to draw the line between public rights -- such as collective security -- and individual rights -- such as privacy.
Foreign aid is a difficult issue since it raises several questions that do not offer obvious answers. An argumentative presentation could take a stance on whether foreign aid should be treated before the alleviation of domestic challenges such as poverty. A presentation could also argue for or against the role of government in foreign aid or whether foreign aid should come with "strings attached," such as the requirement that it be used for a specific purpose or follow certain guidelines.
The cloning of plants, animals and humans is a controversial topic with several angles. An argumentative presentation could examine both sides of cloning: the potential benefits it might offer for humanity, such as increased livestock and plant life, and the potential for protecting certain endangered species; and the potential challenges or dangers of cloning, such as the question of who gets to decide what gets cloned, whether humans are suitable for cloning and whether the potential side effects are worth the risk.