Evaluating Evidence

When reading/listening to others’ arguments as well as planning your own, you must determine if the evidence is credible, accurate, and reliable. If the evidence does not meet these criteria, then your argument is (more) likely to fail.

To evaluate evidence for credibility, accuracy, and reliability, consider the following questions:

  1. Who/what is the source of the evidence? It is important to determine the credentials of the person/group responsible for the evidence, and, depending on where the evidence is found, it may be (fairly) easy to do so. For example, if the evidence is published in an academic journal article, then the evidence is likely credible because of both the person/people responsible for writing the article (a scholar or scholars in the field) as well as the journal that published it (that relies on a peer review process). The author’s/authors’ credentials likely will be found in the article at the beginning or end, and the journal’s will be found on the journal website.
  2. Is the evidence found in a primary or secondary source? A primary source is an original source, such as a literary work, historical document, photo, etc., whereas a secondary source provides content that has already been interpreted (and thus is a step or steps removed from the original). Depending on the scope of the project and the focus of the argument, primary sources may be needed more so than secondary sources and vice versa.
  3. How does the evidence from one source compare and contrast with the evidence from another source? Particularly for academic writing, arguments are generally supported by evidence found in multiple sources. It’s important to consider how evidence may or may not represent a pattern across sources, and the implications of that for the argument being made.
  4. How current is the evidence? Generally you will want evidence to be as up-to-date as possible, particularly in areas such as science, health/medicine, and technology that can evolve quickly. In some cases if evidence is from even just two years ago it may be outdated, whereas in other cases the evidence may have a longer “shelf life.”
  5. Is the evidence specific to the reasons for which it is being provided, and does it ultimately support the claim? Sometimes “tangential” evidence may be all that is available at the time to back a reason or reasons, but almost always the evidence should be specific to the reasons and claim, not merely related.
  6. Why is the evidence important to the argument? Generally when making an argument there are many choices to be made, including what evidence from the range of evidence available is the best to include. Consider whether and why the evidence that has been provided or that you are considering using is necessary to the argument.
  7. What does the evidence perhaps suggest, but not explicitly show? In order to develop a strong argument it’s necessary to consider the possible different interpretations of the evidence, and address them as needed.
  8. What is interesting about the evidence that will make it catch the attention of the reader and be memorable? In some cases evidence that states the obvious may be necessary, but often argument is more complex than that and, therefore, requires more engaging evidence.

evaluating evidence in practice

Earlier in this text, you practiced evaluating a claim using the example, “Media cannot be trusted.” Using that same example, identify what kinds of evidence would be needed to:

  1. Support the claim if the audience agreed with the claim;
  2. Support the claim if the audience did not agree with the claim; and
  3. Refute the claim if the audience agreed with the claim.