The cornerstone of any good paper is a clear, succinct thesis statement. Your thesis outlines the main idea or argument of your paper, which means it can help you properly structure your paper and ensure that you include all relevant information. Reducing a paper to a single idea can be challenging, but strong papers stick to the point.
While your thesis should be structured as a general argument, the nature of your thesis is determined by the type of paper you're writing. An expository paper, which explains a particular concept to the reader, should have a thesis that addresses one specific concept or group of concepts upon which you will expand in the paper. An analytical paper, which breaks down an issue into several parts or influences, should have a thesis that outlines the important elements of an issue for further expansion in the paper. An argumentative paper takes a position on an issue and should have a thesis that explains the argument you'll make in the body of your paper.
Basic Thesis Structure
Your thesis is a statement of the overall theme or argument of your paper, and all other information in your paper should support your thesis. One simple way to construct a thesis is to state a claim and its primary justification. A simple statement of fact is generally less compelling. Your thesis should also be written in strong language. Don't state, for example, "I think positive dog training is best." Instead, you could word this thesis as, "Reward-based dog training has been scientifically proven to be more effective because it works more quickly and results in less stress for dogs and their owners."
The Working Thesis
A working thesis is a general idea of what you want to argue, and it can help you frame your paper before you've done all your research. For example, your working thesis in a sociology class might be that environment affects a child's personality. This statement should not, however, be your final thesis statement -- it's far too broad. As you do more research, you might find a particular element in a child's environment that affects a specific aspect of personality and then hone your thesis to reflect this.
Establishing the Main Idea
A thesis's core role is to establish the central argument of your paper. It's not a title or a topic statement, even if you're addressing a specific topic. For example, your topic might be the role of philosophy in the 20th century, but your thesis should not simply restate this topic. Instead, list a specific point about philosophy's role. For example, "The role of philosophy in society became much less significant with the advent of the 20th century."
To form a clearly argued paper, each paragraph should relate directly back to your thesis. You can even add a mini-thesis, also known as a topic sentence, to each paragraph. For example, if you're arguing that representative democracy is the superior type of government, each paragraph could be devoted to a benefit of this structure, and the first or last sentence could state with specificity the nature of the benefit. This structure ensures that you thoroughly argue your thesis and that any unnecessary information is left out.
Your paper's conclusion should tie back into your thesis without restating it. You can construct a conclusion in a number of ways, but one of the simplest methods is to restate each sub-argument and then emphasize the correctness of your thesis. Another way is to discuss a potential implication of your thesis and arguments or to recommend directions for future research.