Good argumentative writing requires support, including evidence, to convince readers that the writer's argument is valid. Evidence, one of the most common forms of support, is facts and details that bolster an argument. It is proof of the validity of an essay's claims. Evidence can include facts and data, personal research, citation of the research of others, and 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.
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 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 These are the theories, arguments, or ideas proposed by experts in a field of interest.
EXAMPLEIf you’re writing a paper about psychology, you might use evidence taken from publications including the American Journal of Psychiatry.
Research findings These are data from surveys or research experiments.
EXAMPLEIf 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 This is a first-person account of an experience, etc. provided by someone other than yourself.
EXAMPLEIf 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.
Not all research is good or convincing. Good data should have the following qualities:
Data must be current. Statistics and theories that are out-of-date, or that have been disproved, are not useful.
Data must be relevant. It must be directly related to your argument.
EXAMPLEIf you want to make an argument for leash laws, data about zoos is probably not useful. You must locate sources that are relevant to your argument.
Note that your source does not need to make the same argument that you are making, but it must be related to your topic.
Data must be unbiased. If your source is biased, the evidence it provides might not be trustworthy. Think about 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.
Data must be rational. Some of the sources you encounter may not be rational, informed, or expert.
EXAMPLEYou 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, for example those that seek to advance "conspiracy theories," are based in irrational beliefs that are unsupported by facts. Avoid referencing such sources.
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, although 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 websites 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:
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.