Rules for writers, Tenth edition - Diana Hacker, Nancy Sommers 2021

Support your thesis with specific evidence
Writing arguments
Academic Reading and Writing

You will support your thesis with evidence: facts and statistics, examples and illustrations, visuals, expert opinion, and so on.

Using sources responsibly Whether your sources provide facts or statistics, examples, visuals, or expert opinion, remember that you must cite them. Doing so gives credit to authors and shows readers how to locate a source in case they want to assess its credibility or explore the issue. See 57 (MLA) and 62 (APA) for more help.

Using facts and statistics

A fact is something that is known with certainty because it has been objectively verified: Carbon has an atomic weight of 12. Georgia congressman John Lewis died on July 17, 2020. Statistics are based on data and might or might not be factual, depending on the source of the data. If you choose to use statistics, look closely at the source of the statistics. Ask questions: Where do the statistics come from? Can they be verified? Facts can’t be manipulated, but statistics can easily be manipulated so that they are unreliable and unrepresentative.

Most arguments are supported, at least to some extent, by facts and statistics. For example, in the following passage, student writer Julia Riew uses statistics — and cites her source — to show how often captive animals cannot survive in the wild.

Indeed, research indicates that the majority of captive species fail to flourish once reintroduced into their natural habitats: one particularly devastating reintroduction study revealed that “only 16 out of 145 reintroduction projects using captive-born animals were successful” (Keulartz 341).

Writers often use statistics in selective ways to bolster their own positions. If you suspect that a writer’s handling of statistics is not fair, track down the original sources for those statistics or read authors with opposing views, as they may give you a fuller understanding of the numbers.

Using examples

Examples rarely prove a point by themselves, but when used in combination with other forms of evidence, they add detail to an argument and bring it to life. Because examples are often concrete and sometimes vivid, they can reach readers in ways that statistics and abstract ideas cannot.

In her essay on zoos’ role in protecting endangered species, Riew describes how one zoo in particular raised money for conservation projects.

Not only can their educational efforts lead visitors to donate to conservation organizations, but zoos also can raise funds with ticket, food, and souvenir sales that they then pass onto conservation projects. For example, each year the Oakland Zoo donates a portion of every ticket to conservation organizations through an ongoing program called Quarters for Conservation. In 2018, Quarters for Conservation raised $332,000 to help save at-risk species (“Oakland Zoo”).

Using visuals

Visuals can support your argument by providing vivid and detailed evidence and by capturing your readers’ attention. Bar or line graphs, for instance, describe and organize complex statistical data; photographs can convey abstract ideas; maps can illustrate geography. As you consider using visual evidence, ask whether the evidence will appeal to readers logically, ethically, or emotionally. For examples of eight types of visuals to support your argument, see 1f.

In her essay, Riew uses a graph to show readers the dramatic increase in extinction rates of vertebrates, supporting her argument that the “current extinction rate is an unprecedented crisis that impacts all creatures.” To see the visual in Riew’s paper, see 7h.

Citing expert opinion

Although they are no substitute for careful reasoning of your own, the views of an expert can contribute to the force of your argument. To help readers recognize the expert, provide credentials showing why the source is worth listening to — why the expert is, in fact, an expert — perhaps by listing their title or expertise. For example, Riew cites a geological expert who studies ecosystems, Paul B. Wignall, and provides his credentials.

Geologist and environmental researcher Paul B. Wignall designates “human activities” such as poaching, climate change, “habitat destruction, the introduction of invasive species . . . , and the general over-exploitation of natural resources” as the primary causes of this increase (17).