ENG 101 - What is a Thesis

Thesis (plural: theses, pronounced THEES-eez): The point that an essay is trying to prove. Also known as the claim or argument. Everything in a persuasive essay relates to the thesis, either as evidence, explanation, elaboration or rebuttal of alternative claims. Think of the thesis as the spine of your paper. Just as all the parts of your body are connected to the spine, and without the spine your body could not stand, so too in your essay all parts must be connected to the thesis, and without the thesis the essay cannot stand. Parts that are not connected must be revised so that they do connect, or else eliminated. A thesis, in other words, is not the same as the thesis statement, which is a sentence or two in your introduction that tells the reader what the thesis is. The thesis is not limited to one spot in your essay; it runs through the whole thing, from start to finish.

A thesis can be expressed as a statement

Because the thesis is what you’re trying to prove, it must be possible to express it in the form of a statement or assertion (e.g., “the sky is blue”). It is not a question (“what color is the sky?”) or a topic (“the color of the sky”). Notice that “The sky is blue” is a complete, declarative sentence, while the topic (“the color of the sky”) is not—it does not say anything about the sky’s color.

A thesis should be understandable

There’s more to this than you might think. First of all, of course, readers have to be able to tell what your point is. They have to know what you are trying to prove—which, again, is more than just your topic. This means the thesis must be clearly expressed, usually in the introduction, usually with a direct statement.

But not only that. Readers also have to be able to see how all the different parts of the essay relate to the thesis. One of the most common problems with 100-level college writing is that the thesis statement does not match up with the actual thesis—the point or points being made in the body of the paper. When that happens, readers cannot tell what the thesis is. This brings us to the next feature of a successful thesis.

A thesis should be coherent

The thesis must be a single argument that goes through the entire essay. It should not make two separate points, and it should not shift halfway through, so that the thesis expressed in the introduction is abandoned for a different thesis in the body or the conclusion. A complex thesis, with interrelated parts, is ok, as long as it’s clear how the different parts relate to each other.

A thesis should be arguable

An arguable thesis is one you have to give reasons for, that is worth proving (i.e., not obvious). So my example above is not a valid thesis, because everybody knows what color the sky is. An arguable thesis might be, for example, “The sky only became blue about 1 billion years ago, when the composition of the atmosphere changed to produce the specific refraction of sunlight that makes it look blue.” (I have no idea if this is true or not, by the way—it’s just an example.) This statement is not obvious, and it would require evidence about the nature of the atmosphere a billion years ago, and explanations of why that evidence is reliable, in order to be proved.

A thesis can deal with facts, interpretations, or values

Theses can be statements about matters of fact (e.g., the physical structure of the atom, the causes of diabetes), interpretation (e.g., the meaning of Hamlet), or values (e.g., the morality of the death penalty). Your paper should make a persuasive case about some question of fact, interpretation or values, but it should always be based on evidence that everyone can agree on.

Descriptive and prescriptive theses

A descriptive thesis makes a claim about how things are. A prescriptive thesis makes a claim about how things should be. (Think of a doctor’s prescription, which tells you what you should do to get well, as opposed to a diagnosis, which simply describes your illness.) You can agree with someone about how things are even if you don’t share their values. But you can’t agree on how things should be unless you share at least one value. Therefore, prescriptive theses deal with questions of values, ethics or morality.

Here are some features of each type of thesis.

A descriptive thesis

makes an “is” statement
appeals to evidence that anyone (given enough training) can observe and confirm
appeals to logic that anyone (again, given enough training) can test and confirm
deals in measurement, analysis, interpretation, explanation

A prescriptive thesis also uses evidence, logic, measurement, analysis, interpretation and explanation. However, unlike a descriptive thesis, it also

makes a “should” statement
appeals to shared values or morals—assessments of what is “good” and “bad” or “right” and “wrong.”

Some examples of descriptive theses (notice that disagreement on these points is possible, even though they make factual or analytical claims):

Racism in this country has historical roots in “taking land from and destroying indigenous peoples and enslaving Africans to work that land” (Loewen, 143).
Global warming is caused by human activity, not natural changes in the climate.
American popular music is rooted in the folk tradition of African Americans.
The United States does not offer equal economic opportunity to all of its citizens.

Some examples of prescriptive theses:

We all need to work hard to overcome the legacy of slavery and racism.
Global warming must be stopped!
Music teachers should teach the African American roots of American popular music.
Everyone deserves equal economic opportunity.

In some cases a descriptive thesis may strongly imply a prescriptive argument as well (as in most of the examples above). However, note that one can agree or disagree with the descriptive thesis regardless of how one feels about the moral question. For example, you might agree that global warming is real and caused by human activity, but may not believe it is a bad thing.

Works Cited

Loewen, James. Lies My Teacher Told Me: Everything Your American History Textbook Got Wrong. New York: Touchstone, 1996.

English 101