Logos

Learning Objectives

  • Recognize appeals to logos
  • Use the STAR method to evaluate appeals to logos

Appeals to Logos

Key Takeaway: LOGOS

Logos appeals to an audience’s logical side by presenting clear, reasoned arguments supported by evidence.

As writers, we use logos by structuring logical arguments and incorporating facts, statistics, and data to support our points. To create strong appeals to logos, it’s essential to avoid faulty reasoning, such as assuming causation from correlation or making broad claims based on limited evidence.

Examples: Appeals to logos

While logos is a key component of academic writing, it also appears in other places, for example:

  • A car commercial that highlights fuel efficiency in miles per gallon appeals to a consumer’s sense of logic and practicality.
  • A lawyer in a courtroom uses forensic evidence and logical sequencing of events to argue that their client was not present at the crime scene.
  • An investigative report on rising tuition costs includes data on inflation, student debt statistics, and interviews with experts analyzing the causes.

As you work to build logos in your arguments, keep the following strategies in mind:

  • Both experience and source material can provide you with evidence to appeal to logos. While outside sources will provide you with excellent evidence in an argumentative essay, in some situations, you can share personal experiences and observations. Just make sure they are appropriate to the situation and that you present them in a clear and logical manner.
  • Remember to think about your audience as you appeal to logos. Just because something makes sense in your mind, doesn’t mean it will make the same kind of sense to your audience. You need to try to see things from your audience’s perspective. Having others read your writing, especially those who might disagree with your position, is helpful.
  • Be sure to maintain clear lines of reasoning throughout your argument. One error in logic can negatively impact your entire position. When you present faulty logic, you lose credibility.
  • When presenting an argument based on logos, it is important to avoid emotional overtones and maintain an even tone of voice. Remember, it’s not just a matter of the type of evidence you are presenting; how you present this evidence is important as well.

practice

Watch the video below and think about how it appeals to logos.

You can view the transcript for “2009 Toyota Prius Hybrid Cars- Safety Review” here (opens in new window).

Evaluating Logos

Logos may seem like the most straightforward of the logical appeals, but recognizing such appeals is trickier than you might expect. Especially in the age of “alternative facts,” it is important that you be able to recognize valid logical and/or factual evidence.

Key Takeaway: Evaluating Logos with “STAR” Criteria

The STAR criteria—Sufficiency, Typicality, Accuracy, and Relevance—are a handy means of evaluating content and deciding whether or not it is logically valid.

Measure  Question  Examples and Notes

Sufficiency

Is there enough cited evidence 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’.

Typicality

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.

Accuracy

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.)

Relevance

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 acknowledge that the claim is indefensible.

Manipulative Appeals to Logos

Diagramming an argument helps assess whether an appeal to logos is manipulative. Ask yourself: Are the premises true? Does the conclusion logically follow? Is the evidence sufficient, typical, accurate, and relevant? Is the speaker diverting attention from the real issue? These are some of the elements you might consider while evaluating an argument for the use of logos.

Pay particular attention to numbers, statistics, findings, and quotes used to support an argument. Be critical of the source and do your own investigation of the “facts.”

Example: Misuse of Logos

Maybe you’ve heard or read that half of all marriages in America will end in divorce. It is so often discussed that we assume it must be true. Careful research will show that the original marriage study was flawed, and divorce rates in America have steadily declined since 1985 (Peck, 1993). If there is no scientific evidence, why do we continue to believe it? Part of the reason might be that it supports our idea of the dissolution of the American family.

Try It

Study the mapped visualization of crime in the U.S. below and answer the questions about how it appeals to logos.

map of US showing number of crimes per state

The misrepresentation of information or data is often accompanied by logical fallacies. We’ll examine these in more detail later, but they generally jump to conclusions, make generalizations, or frame the argument in a way that manipulates the logic of an argument.

Logos and Kairos

Kairos, the fourth rhetorical appeal, is best understood in relation to the others. The term comes from the Greek καιρός (kairós) and refers to the right timing or conditions for a crucial action—the opportune moment.

Kairos is essential to appeals to logos because logic depends on context. For example, citing a 1960s cancer treatment study without acknowledging advances in medicine would make the information outdated and irrelevant in 2022. Even factually correct information must be timely and appropriate. Understanding the rhetorical situation requires evaluating the timing of an argument to balance rhetorical appeals effectively.

Glossary

logical fallacy: a flaw in reasoning or a flawed structure that undermines the validity of an argument

logos: appeal to logic