Supporting Claims

Kinds of Support Authors Use

Writers are generally most successful with their audiences when they can skillfully and appropriately balance the three core types of appeals. These appeals are referred to by their Greek names: logos (the appeal to logic), pathos (the appeal to emotion), and ethos (the appeal to authority). 

Graphic. Central green circle reads "Persuasion." Three circles connect out from it: at the top, a purple one reads "Ethos / trust / authority." Bottom right, in blue, "Pathos / emotion / beliefs." Bottom left, in turquoise, "Logos / logic / reasoning."

Logical Appeals

Authors using logic to support their claims will include a combination of different types of evidence. These include the following:

  • established facts
  • case studies
  • statistics
  • experiments
  • analogies and logical reasoning
  • citation of recognized experts on the issue

Authoritative Appeals

Authors using authority to support their claims can also draw from a variety of techniques. These include the following:

  • personal anecdotes
  • illustration of deep knowledge on the issue
  • citation of recognized experts on the issue
  • testimony of those involved first-hand on the issue

Emotional Appeals

Authors using emotion to support their claims again have a deep well of options to do so. These include the following:

  • personal anecdotes
  • narratives
  • impact studies
  • testimony of those involved first-hand on the issue

As you can see, there is some overlap on these lists. One technique might work on two or more different levels.

Most texts rely on one of the three as the primary method of support, but may also draw upon one or two others at the same time.

Using the STAR method to Assess Appeals to Logic

Mapping or diagramming arguments you read in a text may help you judge whether an appeal is adequately supported. Applying the STAR Criteria—Sufficiency, Typicality, Accuracy, and Relevance—is one such technique for assessing whether an argument has sufficient depth and clarity.

Measure  Question  Examples & Notes


Is there enough evidence cited to support the conclusion?

Generally, only “strongly” and not “weakly” supported conclusions should be accepted. The more controversial a claim is, the more evidence authors should provide before expecting an audience to accept it. If the evidence is not sufficient, the author may need to modify or qualify the claim, by stating that something is true ‘sometimes’ rather than ‘always’.


Is the cited evidence typical or representative?

If an author makes a claim about a whole group but the evidence is based on a small or biased sample of that group, the evidence is not “typical.” Similar problems stem from relying just on personal experiences (anecdotal evidence) and from “cherry picking” data by citing only the parts that support a conclusion while ignoring parts that might challenge it.


Is the cited evidence up to date and accurate?

Authors using polls, studies and statistics must ask whether the data were produced in a biased way and also ask whether the sample was large and representative of its target population so that results were outside the “margin of error.” (Margin of error: If a sample is too small or not well chosen, results may be meaningless because they may represent random variation.)


Is the cited evidence directly relevant to the claim(s) it is being used to support?

An author may supply lots of evidence, but the evidence may support something different from what the person is actually claiming. If the evidence is not relevant to the claim, the author may need to modify or qualify the claim—or even to acknowledge that the claim is indefensible.