A thesis is the main idea that you are trying to convey in your work. It states plainly what you are trying to persuade your reader to believe.  Therefore, a thesis cannot be a simple statement of fact, because a statement of fact does not require persuasive argument.  However, all facts require interpretation if one wants to derive meaning from them.

Example of a fact: 

“The number of cases of skin cancer per thousand U.S. citizens has increased steadily since the 1920s.” 

This could not be a thesis unless you were presenting a scientific essay on skin cancer rates.  In such an essay you would need to defend your methodology for determining the rate of skin cancer.

Example of a thesis:

“That rates of skin cancer have increased steadily since the 1920s reveals the danger of the American obsession with getting a ‘healthy’ tan.” 

This is a thesis because it requires argument and support.  Note that alternative theses are possible:  “The increase in the rate of skin cancer since the 1920s derives more from Americans’ longer average lifespan than from the popularity of tanning”; “The thinning of the ozone layer has potentially devastating long-term effects on the public health, as shown by the increase in the rate of skin cancer”; etc.

A thesis is also neither a mere statement of topic or outline, nor a general description or characterization, such as one accomplished with merely an adjective.

Example of a purpose statement:

“This essay will examine the system of alliances that led to the outbreak of the First World War.”

“This essay will begin by examining how the German commitment to the Hapsburg Empire and Russian commitment to Serbia turned the assassination of two people into a European War, and then consider what alternatives were possible.”

Note:  These are called purpose statements because they announce the writer’s intention in writing the essay, but they do not actually provide a thesis.  They often reveal that the essay was originally intended as a spoken lecture.  In those cases, outlining one’s presentation at the outset for one’s audience can be helpful.  Purpose statements are common in scientific papers, but seem stiff in the humanities.

Example of a general description or characterization:

“The system of alliances that brought about the First World War was foolish.”  At minimum, this statement needs an accompanying explanation: “The system of alliances that brought about the First World War was foolish because . . . ”

Essays that examine works of literature also cannot merely consist of facts.  These essays are always presumably written for people who have read the work in question.  For example, we can assume that relatively few people are going to read an essay about Madame Bovary without having read the book.  These readers know what happens in the story, novel, or play, or what the poem says on a literal level, so they are not going to be interested in reading an essay merely summarizing the plot or even the overall theme of a work.  Nor are they looking for background information on the author’s life.  Even if they were to enjoy that, knowing more about an author personally would not by itself help them understand the work better, which is what we should presume they want.

Note below the differences between a fact and an arguable point:

Example of a fact in a literary essay: 

“In The Scarlet Letter, Hester Prynne struggles to understand her daughter Pearl’s strange behavior.”

Any reader of the novel knows that this is true.  While you could fill an essay with quotations from scenes that show Hester struggling to understand Pearl, it would not be necessary.

Example of a thesis in a literary essay: 

“In The Scarlet Letter, Pearl may appear to a living embodiment of Hester’s sin, but her ultimate fate suggests that she is an embodiment of true love, and that her flaws are caused only by her father’s refusal to claim her.”

This statement is a thesis because the claim that Pearl is “an embodiment of true love” requires support.  The novel never says that directly.  The writer can only persuade the reader to accept this thesis by quoting the text and then explaining how and why this interpretation makes sense.

Beware of absolutes:  The problem with a thesis such as “George Marshall was the greatest Secretary of State in U.S. history” is that you would have to compare him to all the others, or at least all those who are generally admired. This is possible to do, but probably not in an essay assigned to an undergraduate course, which would not be long enough to accomplish that task.  The same applies to a thesis such as “King Lear is Shakespeare’s most tragic character.”  On the other hand, one can argue an absolute if one sufficiently limits the context:  “Of the four most renowned silent film comedians, Buster Keaton was the most innovative film-maker” is an acceptable thesis because one might reasonably compare four film-makers in a college essay.

Literary and artistic works never prove anything about the real world.  Art creates its own worlds with their own rules.  Thus, a novel that presumes our lives have meaning and purpose and another one that presumes that life is random and meaningless can both be great.  A movie that suggests romantic love is the most fundamental part of our lives (Annie Hall) and a movie that claims that “the problems of three little people don’t amount to a hill of beans in this crazy world” (Casablanca) can both be considered masterpieces.  On the other hand, literary and artistic works can prove something about literature and art:  “By conventional standards, Paul Henreid’s Victor Laszlo is a more admirable man than Humphrey Bogart’s Rick Blaine; thus Casablanca demonstrates that the most effective American cinematic hero is often an anti-hero.”

Be specific: A good thesis is both specific and divided.  Specific means that you avoid general arguments ––– for example, that something is either simply good or bad.  Divided means that you provide an indication of the basis for your argument in the thesis.  Note that sometimes this may require that the thesis be more than one sentence long.

Never use the first person in your thesis, even if your professor permits it elsewhere.  Your name is on the essay, so we know who is making the argument. Thus, a thesis that begins with something like “I would argue that” merely wastes time.  Besides, you want to make your thesis as strong and convincing as possible; phrasing it as a matter of personal opinion weakens it.

Never phrase your thesis in the passive voice.  While sometimes useful, the passive voice is generally weaker and sounds less confident than an active voice sentence.

Never attribute your thesis to someone else, or to general opinion.  A thesis that says “Many people believe” or that some famous scholar or critic believes something is necessarily about “many people” or the famous scholar or critic, not about the point being made, or more importantly the point you are trying to make.

Beware the “alternative universe” thesis.  In literary essays, you must deal with the world the author has created as it is, not as you might like it to be. 

An alternative universe literary thesis: 

“Madame Bovary should never have trusted Rodolphe, and would have been happy if she had met someone else first.”

Perhaps, but if she had not fallen for Rodolphe, she would not be Emma Bovary. You want her not to fall for Rodolphe?  Write your own damned novel!

Ironically, you have slightly more latitude to speculate in social science papers.  Even there, however, any speculation must be both specific and limited.

An alternative universe social science (history) thesis: 

“If Hannibal had only attacked Rome immediately after Canae, he would have won the war.”

You might be able to argue this claim persuasively because it is based on one narrow change, in this case one decision made by a single man.  However, the further you attempt to imagine the consequences of that one change, the less convincing your argument will become.  “Carthage would have then become the dominant Mediterranean power” is less convincing, though possibly defensible.  If you then try to argue “Carthage would have had the same influence on western civilization that Rome has had,” the problem is not that someone could prove you wrong, but that little persuasive evidence either way is possible.

Despite what you may have been told, a thesis can appear in many places in an essay.  If it appears in the first paragraph (usually at the end of the paragraph), the essay is closed-form.  Each paragraph then offers evidence to support the thesis, and the conclusion re-states the thesis and hopefully adds something to it so it isn’t merely repetitious.  The essay takes on the tone of a legal case.  The advantages are that the argument of the essay is immediately clear, and that the reader can connect every piece of evidence you present along the way to the thesis immediately.  The disadvantage is that the tone can be somewhat didactic and confrontational.  Also, it can be difficult to write a conclusion to a closed-form essay that is not merely repetitive.  If your introduction and conclusion could swap positions in your essay with no loss of comprehensibility, you have written a bad conclusion.

In an open-form essay, in contrast, the thesis appears near the end.  The introduction establishes the issue under consideration, whether by a statement of the issue or by way of a rhetorical question.  The issue or question is left “open” at that point, as is the reader’s mind; your reader should not be able to guess your answer by the way you have raised the issue or phrased the question.  The essay is thus potentially more inviting because you are offering the reader the chance to explore an issue with you.  It is as if you and the reader are thinking through the issue together, though in reality you are guiding the reader’s thoughts in the direction you want them to go.  Also, the conclusion will automatically differ from the introduction, which eliminates a common problem of closed-form essays:  the dreaded summary conclusion (see below).  However, the disadvantage is that readers can easily become impatient if they think you are not doing enough of the work. 

Make sure you define the issue in an open-form essay clearly at the outset.  Usually this involves describing an area of controversy, and sometimes you might even mention possible alternative interpretations that can be drawn about the controversy, but in no way should you indicate which answer your favor at this point.  For example, one could introduce an essay about Hamlet with the following introduction:

          Until Act 5, Hamlet repeatedly criticizes himself for unnecessarily delaying the revenge his father’s ghost demands, yet he simultaneously takes several determined and even risky steps toward accomplishing his goal.  He feigns madness, stages a play to elicit evidence against his uncle, and stabs one man to death.   Meanwhile, when speaking to his enemies, he repeatedly makes puns that reveal his sanity, his thinking, and even his intentions, or would if any of the people arrayed against him were clever enough to unravel them.  This apparent contradiction is the central paradox of the play, and a reader’s judgment of both the character and the play’s ultimate passages depends upon how one resolves it.

You may also set up the issue directly by asking a rhetorical question.  Once again, how and why questions (or questions that obviously require or imply a how or why explanation) work better than simpler who, what, when, or where questions, and better than yes/no or either/or questions.  Warning:  you cannot set-up an open-form essay effectively merely by turning the thesis into a question.  When you do that, the answer is almost always obvious, which defeats the whole purpose of writing in open-form.  Think of it this way:  if your answer to a question is “I went to the movies last night with my friends Emily and Kevin,” the question could not have been “Did you go to the movies last night with your friends Emily and Kevin?”  If that had been the question, your answer could simply have been “Yes.”  Instead, the question might have been “Have you been to the movies recently?” or “Have you done anything fun lately?” or “When was the last time you saw any of your friends?” or maybe even “Don’t you ever do anything but study?”

A “delayed thesis” essay starts out open-form, and switches to closed-form partway along.  This form is most effective in somewhat longer essays; in essays of under ten pages it often causes structural problems.

Note:  closed-form and open-form refer only to the way you structure the essay for the reader, not to the way you go about researching the essay and deciding what to say.  That process is presumably always initially open, in that you keep an open-mind while gathering your data.  Then you create a thesis, which you modify as your think through your argument.

A note and a warning:  Although open-form essays are a standard approach that goes back more than four-hundred years to the father of the modern essay, Michel Eyquem de Montaigne, you should check with your professor before submitting an essay in open-form.  Some (a minority, but some) professors, especially in disciplines other than English, are accustomed to closed-form essays and simply expect to see the thesis statement at the end of the introductory paragraph.

Like essays, paragraphs need not be closed-form either.  A closed-form paragraph begins with the main point of the paragraph; an open-form paragraph begins by stating the issue you are examining or by asking a question and settling or answering it in the final sentence; a delayed topic-sentence paragraph places the topic sentence somewhere after the beginning of the paragraph.  The best essays blend open- and closed-form.  If your overall structure is closed-form, some open-form or delayed topic-sentence paragraphs along the way make the essay more involving.  If your overall structure is open-form, you absolutely need to give readers closed-form paragraphs along the way so that they know they are in good hands.

Note that no one objects to open-form or delayed thesis paragraphs, so even if a professor asks you to put the thesis at the end of the introduction, you are still free to vary your paragraph structure throughout the essay.

An essay needs an introduction of some kind.  It is not effective to leap immediately into the details of whatever argument you are making:  the reader will be confused, as if he or she just walked in on a conversation in progress.  A good introduction in an essay is like making a good first impression in person: it encourages the reader to stick around and listen to what you have to say.  A bad introduction will usually result in a reader deciding his or her time would be better spent reading or doing something else.

Most people understand that an essay needs an introduction, but they often have a poor sense of audience and purpose — who will be reading their essay and why.  As a result, one common problem in essays is that the introduction starts out too generally.  You should usually assume your reader has at least a general interest in your topic, and perhaps more.  After all, few people would pick up an essay about William Faulkner’s As I Lay Dying without having read the book.  Therefore, you should never start out a literary essay with basic information such as

          William Faulkner’s As I Lay Dying appeared in 1930.  It was his fifth novel.  The novel focuses on the Bundren family and their journey to bury Addie Bundren.  Faulkner writes the novel in a stream-of-consciousness style.

The problems here are twofold: anyone who has reathe nove already knows everything you have said, and some of this information is probably irrelevant to the essay’s argument.  Does 1930 matter?  Does it being his fifth novel matter?  Each conceivably might:  the year could matter in an essay that discussed the novel’s relationship to contemporary events such as the stock market crash and the beginning of the Great Depression, and when the novel occurs in Faulkner’s career could matter in an essay that discusses the development of his style over time.  But right now, those facts seem irrelevant, and probably are. This also gives the reader the impression you are trying to pad the essay’s length and lack a strong sense of why you are writing.

One other common error students make in literary essays is to start out writing as if their subject is life and not literature.  This is also a problem of audience:  students sometimes think that unless they go out of their way to make their essays relevant to their readers’ lives, the readers will not care.  But again, people who decide to read an essay almost certainly already have an interest in the subject — in the case of a literary essay, the play, poem, story, novel, whatever — and do not have to be convinced of its relevance to their lives.  Therefore, do not start a literary essay by making an argument about life.  More times than I can count, a student has begun an essay with something like this:

          From the beginning of time, teenagers have rebelled against their parents by falling in love. Everybody agrees love is important, but no one seems to know how to go about learning how to act when one is in love.  We all expect our first love to be special and last forever, but usually it ends up being ruined by misunderstandings. On the other hand, maybe it is those experiences that allow us to love in a more mature way.  People never want to break up with their first loves, but what if the only way to make that happen is to die?  Parents want to protect their children from falling in love with the wrong person, but how can they know what their children truly feel?  These are the kinds of issues William Shakespeare deals with in Romeo and Juliet.

In a word, ugh! First, teenagers did not exist at “the beginning of time.”  Second, this paragraph contains no real thesis statement, nor does it raise literary questions.  Third, it puts words in the readers’ mouths that they may not accept, such as the assertion that “we all expect out first love to . . . last forever.”  But most importantly, none of this will be of interest to a reader looking for help with Romeo and Juliet.  Readers of critical essays neither expect nor wish to be lectured about love.  The play, and not reality, should be the subject because literature never proves anything about reality in any case; you cannot answer questions about love by reading any play, even one by Shakespeare, who incidentally returned to the subject many times, usually much more cynically than he appears to write in Romeo and Juliet.  And to be blunt, the odds that a brief college essay can answer the big questions about love (or human nature, or metaphysics, or ethics) — questions that humanity has tried to answer for thousands of years — are infinitesimal, while the odds that you might have something interesting to say about a literary work are actually pretty good.  Write about literature, not life!

In an open-form essay, the conclusion provides the answer to the question or settles the issue that the introduction presents. In a closed-form essay, the conclusion returns to the thesis and reconsiders it in the light of the evidence the essay has presented.  The conclusion should never simply re-state the thesis.  If you can switch the introduction and conclusion without losing any comprehensibility, you have written a bad conclusion.

The task of a conclusion is to pull a paper together and leave the reader on a strong note. Remember that your readers will not take nearly as long to read your paper as you took to write it (at least, so you should hope), and you should presume their memory is good enough that they can remember what you said a page or two earlier.  Indeed, the papers required in undergraduate courses will seldom be so long that you need to remind your readers of your own argument at the end.  Therefore, phrases such as “As I have argued,” “As stated above,” or “I have already said” are all signs that you are about to repeat yourself in a particularly uninteresting way.  These so-called “summary conclusions” can be helpful at the end of a book or even a densely written chapter of twenty pages or more, but at the end of a five- or ten- or twelve-page paper are unnecessary. 

Another usually poor tactic is to end your paper on a quotation from a secondary source (a critic, for example).  After spending all that time trying to convince your reader that you are someone worth listening to, why would you want to abandon the end of the paper — the last chance you have to leave a lasting impression with your reader — to someone else?

Finally, do not throw up your hands and admit defeat, or even worse apologize.  I have seen fairly good college level papers torpedoed by a bizarre form of mea culpa at the end, such as, “No matter how many times one reads this poem, in the end everyone is going to have his own opinion on it.  My interpretation is no better than anyone else’s, and that is what makes it a great poem.”  Obviously, that completely undercuts whatever point you have been trying to make.  Have the courage to stand behind your opinions — at least until someone shows you where the flaw in them lies. Of course, this is easier to do if you have put real thought into them and challenged them yourself first.