You can’t rely only on common knowledge when you make arguments in academic and professional settings. Readers expect you to use reliable evidence taken from reliable sources.
Readers can't know whether your source is reliable unless you cite it. When you cite sources, you help yourself and your readers in three ways:
Most importantly, when you cite your sources you give credit to those whose work you rely on, paying them back in a small way for helping you make your own argument more credible.
Academic and professional readers regularly check sources not only to make sure that evidence is convincing and accurate but also to use that evidence in their own arguments. Just as you can use the citations in your sources to find additional sources, so your readers can use yours. Accurate and complete citations keep writers honest, but more importantly they locate your work in a web of research that makes us all smarter.
Let’s look at a paragraph from a student’s paper written for an education class. The writer’s main claim is that child labor laws in the U.S. are focused on urban employment and ignore children in rural communities. In this paragraph, the writer presents a number of facts as evidence for her argument.
Generally, readers do not expect citations for information they think of as common knowledge. They also do not expect citations for dates or other discrete facts that can be found in reference works. But they do expect a citation for any information they could not have known without the writer’s help.
In judging when you need a citation, you have to make a separate decision about each piece of evidence. Here is the passage again with footnotes.
Since the 19th century, the laws regulating child labor in the United States have increasingly limited the hours and types of work that children under age 16 can perform. Before the 19th century, there were no laws regulating child labor, and many children worked long hours in mines, factories, and farms. In 1836, Massachusetts passed the first law requiring children under 15 working in factories to attend school at least three months per year.1 This law did not limit the number of hours a child could work per day, however. In 1842, Massachusetts passed the first law limiting children’s work days to 10 hours per day.2 The first national regulation of child labor came in the Fair Labor Standards Act of 1938.3 Today, children may begin working as employees at age 14, so long as the job is not dangerous and does not interfere with their schooling. But relatively few American children work. Those that work mostly do so not to support their families but to supplement their spending money. Twenty-one percent of those in the lowest-income group held employee jobs when they were 14, compared with between 25 and 27 percent of those whose households had incomes in the three higher groups.4 Most of this is summer work: only 4 percent of 14-year-olds and 8 percent of 15-year-olds work more than 15 hours per week during the school year.5 But if child labor laws protect children working as employees, many children work off the books in family businesses, such as farms, which have fewer regulations.6 This work can be quite dangerous, and more than 200,000 minors suffer work-related injuries every year.7 Thus, while child labor regulation has changed drastically since the 19th century to protect a majority of American youths, a small number of young people continue to work long hours during the school semester, occasionally in dangerous conditions.
1 University of Iowa Labor Center and Center for Human Rights, “Child Labor in U.S. History,” Child Labor Public Education Project, http://www.continuetolearn.uiowa.edu/laborctr/child_labor/about/us_history.html (accessed July 14, 2009).
2 "Child Labor."
3 “Fair Labor Standards Act: Acts, Bills, and Laws, 1938-Present,” Travel and History, http://www.u-s-history.com/pages/h1701.html (accessed July 17, 2009).
4 United States Bureau of the Census, Report on the Youth Labor Force, 2000, http://www.bls.gov/opub/rylf/pdf/rylf2000.pdf.
5 Youth Labor Force, 17.
6 Youth Labor Force, 56-60.
7 The Child Labor Coalition, “Health, Education, and Labor and the Convention on the Rights of the Child Symposium,” http://www.dianahacker.com/resdoc/p04 _c08_s2.html (accessed July 22, 2009).
