In this lesson, you will learn about the types of evidence that can be used in an essay to support assertions and convince readers, as well as how to evaluate certain types of evidence. Specifically, this lesson will cover:
- Types of Evidence
- Researched Evidence
- Evaluating Research
- Locating Sources and Avoiding Bias
1. Types of Evidence
Good argumentative writing requires support to convince readers that the writer's argument is valid. Evidence, one of the most common forms of support, is comprised of facts and details that bolster an argument. It is proof of the validity of an essay's claims.
Recall that evidence can include:
- Facts and data
- Personal research
- Citation of the research of others
- Personal experiences
Although evidence can be useful in any mode of writing, it’s particularly important when making an argument. Writers who support their claims with evidence are more likely to convince readers to agree with them. When making an argument, writers most often use researched evidence to support it.
- Proof of the validity of a claim or claims.
1a. Researched Evidence
Although there are other types of evidence, research is a common and effective way to support claims. Research is a fact-finding process in which data, statistics, and ideas from other writers and sources are located and identified to support your ideas. Researched evidence is thus evidence that you have found in external sources.
During research, writers commonly investigate books, newspapers, websites, scholarly journals and experimental results for information that enables them to make convincing arguments.
Researched information can include the following sources:
Expert arguments, which are the theories, arguments, or ideas proposed by experts in a field of interest.
- If you’re writing a paper about psychology, you might use evidence taken from publications including the American Journal of Psychiatry.
Research findings, which are data from surveys or research experiments.
- If you’re writing about school lunch programs, you might use evidence provided by the U.S. Department of Education about how many students eat program-provided lunches nationwide.
First-person data, which are first-person accounts of an experience provided by someone other than yourself.
- If you’re writing an argument calling for increased funding for the Veterans Administration, you might include an interview with a veteran to describe why the VA is important to many people.
All of these types of research can be useful and can lead you to the application of good researched evidence.
- A fact-finding process in which data, statistics, and ideas from other writers and sources are located and identified to support an essay's ideas.
2. Evaluating Research
Not all research is good or convincing. Good data should be:
First, data must be current. Statistics and theories that are out-of-date, or that have been disproved, are not useful. Data must also be relevant, meaning it is directly related to your argument. Your source does not need to make the same argument that you are making, but it must be related to your topic.
If you want to make an argument for leash laws in local parks, data about zoos is probably not useful.
Data must be unbiased. If your source is biased, the evidence it provides might not be trustworthy. Consider the informative mode of writing, in which data are presented an unbiased manner— without taking a side on the issue. That’s the kind of data you need in order to take a position of your own, and to support that position believably and ethically.
Finally, data must be rational. Some of the sources you encounter may not be rational, informed, or expert.
You may hold strong opinions about orcas (i.e., killer whales), but you should not be cited as a rational source if you don’t have any expertise on the subject. Your evidence would be based by your opinions, which may be incorrect.
Some sources, such as those that seek to advance "conspiracy theories," are based in irrational beliefs that are unsupported by facts. Avoid referencing such sources.
3. Locating Sources and Avoiding Bias
When looking for sources, news reports are often a good place to start. They may contain summaries of information that you can use directly in your essay, and that may lead to other sources. However, while news reports can seem neutral, they are sometimes tainted by political or social biases. Make sure that your source is not partisan.
Libraries and library databases are a good source of scholarly publications. When you find a useful book or article, the bibliography in that publication can lead to additional resources.
Some websites provide a wealth of information. Blogs and commercial websites cannot be assumed to be unbiased, but they might provide useful first-person data. In contrast, websites that end in .gov or .edu often provide neutral and detailed research findings.
Wikipedia can be a good place to start research, but it is not a valid academic source because anyone can edit any page. The information cannot be verified.
When examining a source, ask yourself the following questions:
Who wrote this and when was it written?
- Getting a sense of who the author is and the context of his or her work will indicate whether or not it is current, unbiased, and rational.
Who published this?
- If you’re investigating a website or a news article, check the “masthead” of that publication. A masthead is a list of the people involved in the publication, and may include contact information. Regarding websites, look for a link to an "About Us" page (or something similar).
- Use a search engine to find information on a news source, and also look at its Wikipedia page. This is a good way to make sure that a source is unbiased, and that you’re not accidentally citing humor or satire.
What are the methods?
- To identify the methods used to achieve the results or findings provided by a source, look for a section called "Methodology." This is particularly important for research experiments, polls, and similar data. If the methods indicate that the research has a narrow scope but is being applied broadly, that’s a warning sign that it isn’t reliable information.
What kind of information does this source cite?
- If you review its bibliography, do you find good, trustworthy sources, or do the sources listed there appear biased?
Although there’s no sure-fire way to determine whether or not a source is valid, the more you research, the better you’ll become at distinguishing the good from the bad.
In this lesson, you learned that the primary type of evidence used to support a written argument is researched evidence. Researched evidence encompasses the facts and details that writers locate in other sources. Before using researched evidence in written work, it’s important to evaluate your research to ensure that it is correct, relevant, unbiased, and rational.
You also learned about ways to locate sources and avoid bias. News reports and websites can be great sources of information, but it’s important to make sure that they present information in a neutral, factual way.
Best of luck in your learning!