Man giving a presentation.Logos, as with the previous two Greek words, provides the English language with several words, with the most obvious one being logic. Literally translated, logos means “word” or “to reason.” People use logos to invoke logical, rational arguments to make an appeal to reason. The most important element to logos is whether or not the argument makes sense to the audience. Establishing strong logos involves using credible facts, statistics, and evidence that supports the various claims of the speaker.

Sometimes people find themselves subjected to a persuasive argument that did not make much sense, leaving them wondering why they became persuaded at all. Perhaps a salesperson convinced them to purchase a product that they would never likely use, leaving them wondering how the salesperson arrived at the conclusion that it would be a natural fit. This offers a glimpse pf what it feels like to experience arguments based in poorly constructed logos.

Types of Reasoning

To construct well-reasoned logos, understand the two types of reasoning people may use to develop arguments: inductive reasoning and deductive reasoning. According to the Internet Encyclopedia of Philosophy, inductive reasoning is:

…an argument that is intended by the arguer merely to establish or increase the probability of its conclusion. In an inductive argument, the premises are intended only to be so strong that, if they were true, then it would be unlikely that the conclusion is false.

For example:

  • Two witnesses claimed they saw Eric commit the murder.
  • Eric’s fingerprints are the only ones on the murder weapon.
  • Eric confessed to the crime.
  • Therefore, Eric committed the murder.

Though unlikely, certain scenarios exist where Eric did not commit the murder. Deductive reasoning, on the other hand, tends to be more grounded and possible to prove true. According to the Internet Encyclopedia of Philosophy, a deductive argument is:

…an argument that is intended by the arguer to be (deductively) valid, that is, to provide a guarantee of the truth of the conclusion provided that the argument’s premises (assumptions) are true. This point can be expressed also by saying that, in a deductive argument, the premises are intended to provide such strong support for the conclusion that, if the premises are true, then it would be impossible for the conclusion to be false.

For example :

  • All members of the Honor Society must have a 3.8 GPA or higher.
  • Sarah is the a member of the Honor Society.
  • Therefore, Sarah must have a GPA of 3.8 or higher.

Deductive reasoning, therefore, offers a more concrete way of arriving at logical conclusions, whereas audiences will often use inductive reasoning in response to a deductive argument when they create objections to the speaker’s reasoning.

To explain this concept using a real-life scenario, pretend a speaker is trying to convince an audience to try a new weight loss program or diet:

diet photo

  • This new diet will reduce your hunger. (Premise A)
  • This reduction in hunger will reduce the amount you eat. (Premise B)
  • Reducing the amount you eat will result in weight loss. (Premise C)
  • This new diet will, as a result, cause weight loss. (This is a sound, deductive conclusion that must be true if premises A, B, and C are true.)

While using sound, concrete deductive reasoning, what could the audience be thinking?

  • breaking diet photo“Every time I have tried something like this in the past, I failed miserably.” (Premise D)
  • “This new program is just like those failed diets.” (Premise E)
  • “This new diet will fail miserably.” (This is a reasonable inductive conclusion drawn from premises D and E.)

Because the audience based their conclusion on strongly ingrained emotional experiences tied to failure, it presents a high degree of pathos and probably outweighs the strength of any deductive conclusion. If the audience has to resolve conflicting emotional conclusions, then they will look for flaws amid the speaker’s arguments, often resulting in imaginary flaws that do not even exist. Regardless of the sound deductive conclusion, the audience will doubt the premises:

  • “But I’m always hungry when I am on a diet!” (Counters premise A)
  • “But if I reduce how much I eat, I won’t have enough energy to exercise, and I’ll gain weight anyway!” (Counters premise C)

How could a speaker remain persuasive in this challenging scenario?

Note to Self

Remember, that in persuasion, your success depends greatly on your ability to make your argument stronger while, at the same time, making opposing arguments sound weaker.

A speaker has a couple of options:

  • Boost the argument by providing supporting facts, research, or even a personal success story with the new diet program.
  • Show why this new program is unlike past failures.

If successful, the speaker would cast a shadow of doubt on premise E, and therefore, the audience’s entire inductive argument.


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Messages that Matter: Public Speaking in the Information Age - Third Edition Copyright © 2023 by North Idaho College is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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