A thesis statement:
Academic papers are arguments and not reports. A thesis statement encapsulates the central thrust of the argument in one or two sentences. It emerges after a lengthy process of thinking and examining the information you have gathered. A thesis usually appears at the end of the introduction.
A thesis statement is not:
Philosophy
Hobbes correctly argues that government’s primary responsibility is the safety of its people, which is clearly a necessity on social, economic and even theological levels.
History 1
While in practice colonialism was almost universally brutal, its existence created a set of political, military, and economic institutions that prepared newly formed states for the globalized world.
History 2
While some historians believe that the fall of Rome was caused by internal decadence, Rome’s political decline was actually a result of military over-expansion and fiscal irresponsibility.
Government
Special interest groups are often criticized, but these groups of citizens represent diverse interests in society and are essential for democracy to flourish.
Literature
Toni Morrison's novel Beloved demonstrates the horrific effects of slavery on the human psyche through the protagonist, Sethe.
Developing a strong thesis takes time and is part of the writing process. Start with a working thesis so that it will guide your writing, and as you begin to write you will be able to refine your thesis statement. These resources will help you to develop a strong thesis statement:
Developing a Working Thesis - from the Writing Center, University of North Carolina at Chapel Hill guide
Developing Strong Thesis Statements - from the Purdue Online Writing Lab
Steps in Constructing a Thesis Statement - from Harvard College Writing Center