An argumentative thesis statement outlines the topic's central argument. The writer must understand the subject well and formulate the thesis around a central point he hopes to stress to the intended reader. The writer should explore all aspects of the topic and brainstorm points the paper will highlight. These points --- which should argue for or against the central theme --- are introduced by the thesis statement in the paper's first paragraph.
An argumentative thesis statement must be constructed around a debatable topic with at least two perspectives. There should be a significant number of people who disagree with the chosen topic. The writer must take a stand on the side of the topic she will argue for or against, and provide a clear case for a reader's consideration. A thesis stating a recognized fact like the earth's roundness cannot be debated, which makes it an ineffective argumentative thesis. However, whether health care in the United States should be subsidized by the government has opinions on both sides of the issue. This latter example could be effectively constructed into a decisive argument for or against that topic.
An argumentative thesis statement is a very narrow and specific point about a much broader topic. It must have a strong focus on the issue to be presented to the reader. Essentially, an effective thesis statement does two things: it informs the reader what the thesis is about, and it takes a stand on the chosen topic. An example of a strong argumentative thesis statement would be, "More attention should be given to the nutritional content of school lunch menus in public schools." This is direct and sets up the argument. Strong thesis statements take a definitive side of an issue as in this example, "While many Americans view the nuclear family structure as the ideal, loving families are defined in many ways."
Effective argumentative thesis statements should be interesting. They should draw in the reader, causing him to want to learn more. A bad example of an interesting thesis statement would be, "Mark Twain was a good writer." Although this idea can be argued based upon likes and dislikes of his work, it is a weak and boring statement. A good example might be, "Mark Twain's writings comically expressed and sometimes mocked "civilized society;" by using metaphor and literature in an indirect way, he highlighted what he believed were problems of the day."