Writing Thesis Statements as Enthymemes

By Jennifer Fletcher

In my new book Writing Rhetorically, I share one of my favorite quotations from rhetoricians Edward P.J. Corbett and Rosa A. Eberly: “Reasoning, by itself, will not get the potatoes peeled” (1). It takes humans in communication with other humans to accomplish real work in the world. When we reason rhetorically, we pay close attention to how and what our audience thinks because we care about the outcome of our efforts.

A good way to sharpen students’ awareness of other people’s beliefs and assumptions is to teach thesis statements as enthymemes.

What’s an Enthymeme?

Like Stephen Toulmin’s concepts of warrants and backing, the classical enthymeme is another logical tool predicated on audience knowledge (see my post on faulty warrants). An enthymeme is a compressed syllogism. It allows people who share common assumptions to “collaborate on an inference,” as Thomas Farrell expresses it in “Practicing the Arts of Rhetoric: Tradition and Invention” (83). Enthymemes are the ultimate audience participation move. When rhetors and audience members have similar background knowledge, the rhetor can leave some things unsaid, knowing the audience will supply this content themselves. It looks like this:

“He would not take the crown; Therefore ’tis certain he was not ambitious” (Act III, scene ii, lines 117-8). 

From Julius Caesar by William Shakespeare

The unstated premise is that an ambitious person would have desired the crown; this idea is already in the mind of the audience, so it doesn’t need to be said.

If you compare that to a syllogism (here’s one I created for Mustafa Mond’s speech justifying the World State in Aldous Huxley’s Brave New World), you’ll notice how much an enthymeme leaves out:

A Syllogism from Brave New World (1932)
Chastity leads to destructive passions.
Destructive passions lead to the end of civilization.
Therefore, chastity leads to the end of civilization.

You could have your students turn this syllogism into an enthymeme by omitting the premise. Like so: 

Chastity leads to the end of civilization because it creates destructive passions. 

Again, the audience helps construct the meaning by supplying unstated assumptions.

Today’s students encounter and produce enthymemes in their daily lives. If someone says, “I can’t tell you anything more—security,” we understand that sharing information could endanger people or property. That’s an enthymeme. As my colleague John Edlund pointed out to me, Internet memes are enthymemes; they make widely recognized cultural references through a single image and a few words.

My daughter’s birthday list request for holographic nail polish was expressed as an enthymeme: “holo polish (because rainbows).” I heard this enthymeme in an NPR report on the national budget while driving home from work: “Putting money in one area doesn’t automatically mean money is available for another area because…politics.” Truncating a rationale to “because rainbows” or “because politics” only works if all audience members understand that rainbows are awesome and politics are complicated. The success of an enthymeme depends on a careful audience analysis.

Like the literary device of irony, the enthymeme requires audience participation.

Writing Thesis Statements as Enthymemes

The University of Oregon’s composition program uses the enthymeme as a strategy for teaching students to write thesis statements. Drawing on faculty member John T. Gage’s work in The Shape of Reason, Oregon Ducks learn to uses the enthymeme “as the central basis for the invention and structuring of arguments” (XV). In contrast to more rigid and formulaic approaches to logic, the enthymeme offers an informal method of rhetorical reasoning that fits well with today’s communication contexts. The enthymeme, Gage says, is “open and flexible” (58), making it a proper tool for a generation that can expect an escalating pace of change in their future.

Enthymemes are made up of a reason, an assumption, and a conclusion (61). The assumption and conclusion may be stated or unstated. In the case of my daughter’s birthday request—“holo polish (because rainbows)”—most of her message was unstated, but I still understood she meant, “I want holographic nail polish because holograms create rainbows and rainbows are awesome.” 

Gage explains that “a thesis statement in the shape of an enthymeme will have the following very basic but elastic form”: 

Assertion 1 (thesis) because Assertion 2 (reason) (77)

The reason can come in the first or second part of the thesis statement.

Because ____________________, ____________________________ .
Since ______________________, ____________________________ .
____________________________ because _____________________ .
____________________________ since _______________________ .

Gage provides a checklist for testing whether a thesis is an enthymeme:

  1. Is the because clause a complete, precisely stated idea?
  2. Does it represent a central reason for answering the question “What makes the thesis true?”
  3. Is the implied assumption one that my audience can be expected to accept without further argument?
  4. Have I explored the adequacy of my reasoning in terms of the relevance and connectedness of the because clause, the relative precision of all the terms, and the need to go beyond circular reasoning? (78)

In other words, does the thesis address a question at issue, provide a supporting reason, use a shared assumption, and avoid vague terms? If it does, students have found a “central basis for the invention and structuring of arguments” (Gage XV).

They’ve also found a way to deepen their understanding of other people. You don’t have to be a mind reader to reason rhetorically, but you do need to make a good faith effort to learn about your audience and be willing to collaborate in making meaning.

Jennifer Fletcher is a professor of English at California State University, Monterey Bay and a former high school teacher. You can contact her at jfletcher@csumb.edu or on Twitter @JenJFletcher.

Works Cited

Farrell, Thomas. “Practicing the Arts of Rhetoric: Tradition and Invention.” Philosophy & Rhetoric.
Vol. 24, No. 3, Theory and Praxis (1991), pp. 183-212.

Gage, John T. The Shape of Reason. Allyn and Bacon, 2001.

3 thoughts on “Writing Thesis Statements as Enthymemes

  1. This is excellent, Jennifer. It’s exactly what I taught in both ELA and speech communication. In my Comm 1101 classes ISU required students to write enthymemes as syllogisms on their outlines for both their argumentative and persuasive speeches. I taught categorical, hypothetical, and disjunctive syllogisms, as well as five forms of inductive evidence. Students also had to test their arguments. I first learned about syllogisms in high school, and they became the cornerstone for how I understand argument. Having a “formula” really helps kids, as well as finding ways to avoid the big words until after kids get the hang of writing the enthymeme.


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