The following is an excerpt from Celia Millward and Jane Flick, Handbook for Writers, Canadian Edition (Toronto: Holt, Rinehart and Winston of Canada, Ltd., 1985), pp. 323–325.

Perhaps the single most important component of a good paper is a clear thesis. The thesis of a paper is its main point, its central idea. It is the reason you are writing the paper (aside from the fact that your instructor told you to). A thesis statement sums up in one sentence the message you want to convey to your readers.

Formulate you thesis before you begin the actual writing. A good thesis statement helps you focus your thoughts about your topic before you start to write, and it helps you stick to your thesis as you write. It is much harder to revise an already written paper to provide a clear thesis than it is to begin writing with a thesis in mind.

Suppose you have been assigned a paper on interpersonal relationships, and you have narrowed that broad topic to “the generation gap.” What precisely do you want to tell your readers about the generation gap? There are many possible thesis statements for this topic.

  1. The generation gap is a fiction invented by sociologists and perpetuated by the media.
  2. The generation gap has resulted from the breakup of family life.
  3. There will always be a generation gap because parents will always be reluctant to allow children to make their own decisions.

If you had decided on the first thesis statement, you would probably develop your paper by suggesting that the very invention of the term “generation gap” had made people feel that one existed. Then, as the term was made popular by television and magazine articles, people came to believe that the generation gap must exist because everyone was talking about it. People might even have begun to feel that something was wrong with their own families if everyone got along well together. No one even tried to resolve any problems between generations because they thought that these problems were only natural.

Thesis statement No.2 implies a very different development. You might use census data or other statistics to show that one generation has lost contact with the next because older people no longer live with their adult children. The high divorce rate has produced many households in which even young children are separated from at least one of their parents. The accelerated pace of modern life has meant that family members spend little time with one another.

If you chose thesis statement No.3, you would suggest that the only thing new about the generation gap is the name. You might use historical examples of conflict between generations, and you could focus on the innate desire of parents to protect their children from what the parents feel are foolish decisions and behavior.

A good thesis statement is specific and unified but not self-evident. A specific statement not only indicates the main point of the paper exactly, it also avoids vague generalities.

Teaching is a noble profession. The first-grade teacher is responsible for the most important skill we possess: reading.
Pollution is a serious problem in North America. Acid rain is destroying fish stocks in the Great Lakes.
You don’t have to be rich to be happy. A vacation in a provincial park can be both delightful and inexpensive.

A unified statement includes only one idea or perhaps one main idea and one or two closely related subsidiary ideas. Consider the statement “The differences between moths and butterflies are often very subtle, but coloration, produced in only two ways, is not one of them, even though there are many, often contrary, explanations for color variation.” This statement lacks unity because it contains at least three major ideas: (1)differences between moths and butterflies are often very subtle; (2)coloration in moths and butterflies is produced in only two ways, and (3)there are many, often contrary, explanations for color variation. Any one of these is a potential thesis statement, but you could not unify and develop all of them within the limits of a short paper.

I like watching sports events on television, and I also like to participate in sports. My love of spectator sports does not prevent me from participating in sports myself.
Many students do not like to read Chaucer, and they prefer Shakespeare, whose language is easier to understand. Many students do not like to read Chaucer only because his language is hard to understand.
Even though we do not have much political terrorism in North America, it is an inexcusable way of trying to get one’s demands. Political terrorism is never excusable.

Self-evident statements are those that need not be made at all because everyone agrees with them; there is no point in writing a paper arguing that horses are bigger than rabbits.

Automobile accidents cause many injuries and deaths. Playground equipment causes many injuries and deaths.
Poor people have less money to spend than rich people. If doctors can opt out of Medicare, the rich may receive better medical care than the poor.

Although you should strive for a thesis statement that is specific, unified, and not self-evident, you need not try to make the thesis statement as dramatic or as shocking as possible. Do not claim more in your thesis statement than you can justify in the paper itself.

Overpermissive parents are the cause of juvenile crime. Overpermissive parents are one cause of juvenile crime.
Napoleon was an incompetent general whose victories were due to luck alone. Napoleon’s victory at Wagram can be attributed more to his luck than to his military genius.

When you actually start writing the paper, include the statement of your thesis near the beginning. You may be able to use your original thesis statement in your paper, or you may have to re-word it to make it fit in with your introductory material.

After you have started writing, you may find that your paper cannot be developed exactly along the lines of your thesis statement. If so, re-state or revise your thesis rather than ignoring it or trying to justify an unworkable thesis. Even though you may have to revise your thesis as you go along, you should have some thesis in mind at every stage of your writing.