Logos Explained: Examples of Logical Appeal in Effective Speaking

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Welcome to the final installment in our series on public speaking examples of pathos, ethos, and logos. We’ve regaled you with moving pathos examples from speakers skilled in wrenching the hearts of the audience. And we’ve presented examples of ethos where experts rely on their unique qualifications or perspective to make their point. Finally we’re doing a deep dive into examples of logos in persuasive rhetoric, so you can apply the same strategies to your own signature talk. 

In these speeches, speakers appeal to reason, logic, and truth. You’re probably thinking: shouldn’t every speaker do that? You’re right! Using logos is a non-negotiable for every speaker. Logos is paramount in every industry, for every type of talk, to any size of audience. After all, the goal of speaking persuasively is, at its core,  communicating some truth to your audience that they don’t already know (or don’t fully understand). That means mastering the proper way to leverage facts, data, and evidence to make an argument. Otherwise, your audience will be left skeptical, ignorant, or misled. It’s easy to get carried away by other secondary goals when you’re preparing your talk, but making a clear argument should always come first. 

Today we’re looking at a variety of logos examples from bygone heroes, public figures, and industry experts. As you soak in their words and their arguments, look for patterns that you can apply to your own signature talk.

Logos: an Appeal to Reason 

Before we dive in, it’s only reasonable (hah!) to review the basics. So what exactly is logos in the context of public speaking? In Ancient Greek, logos refers to reason. Yes, this where we get the word “logic” (as well as any word that ends -logy). When you appeal to logos as a public speaker, it means you prove that something is true with evidence and a sound argument. 

In any great talk, pathos, ethos, and logos will all work together to persuade the audience. But if you have to pick one, logos is the most important. If you use bad data, steal someone else’s story, or commit logical fallacies during your talk, it can undermine your ethos and ruin whatever good impression your pathos and ethos made on your audience. On the other hand, if you are a first-time speaker with low emotional appeal, your audience can still learn from your content if it is backed up with data and well-argued. If you are relying on one pillar of your talk, it should always be logos. 

Leveraging logos by avoiding fallacies

Avoiding the pitfalls of logical fallacies is a great way to start getting better at this type of rhetoric. Many well-meaning speakers undermine their message by committing logical fallacies. You’ve probably started nodding off while a speaker makes a long-winded circular argument that restates the claim over and over without providing real evidence. Or perhaps you’ve heard an enthusiastic presenter encourage the audience to make a change purely because others are doing it–a classic bandwagon fallacy. While slipping into a fallacy once or twice while you’re on the hot seat during a Q&A is forgivable and human, don’t let it become part of your personal brand.

Logical fallacies aren’t always easy to identify in real time, and audiences can and do fall for them. So speakers keep getting away with them while relying on other appeals to make a good impression. Don’t be one of those speakers! If you want to build your credibility and create an impact through a sustainable speaking platform, you have to strive to do better. Becoming a great speaker means going the extra mile to set yourself apart. And long term, that’s what gets you booked and paid to speak.

Without further ado, let’s look at some examples of logos from speakers who set themselves apart with persuasive arguments that get to the truth. 

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Frederick Douglass: “What to the Slave Is the Fourth of July?” 

Even though it’s long, it’s worth setting aside some time to read the entirety of “What to the Slave Is the Fourth of July?” This magnificent and moving talk demonstrates pathos, ethos, and logos throughout. Douglass was a true master of rhetoric who educated himself on the topic of oratory as an enslaved youth. His knowledge of rhetoric and his knowledge of the constitution shine through in this logos example. We highly recommend reading the corpus of his oratory if you’re ever on a history kick or need some inspiration for speaking on social justice topics. 

Douglass appeals to reason by examining the documents of the American Founding. Using the source evidence, he points out the hypocrisy with which their words have been twisted to defend slavery. Hence his stirring words: “Take the constitution according to its plain reading, and I defy the presentation of a single proslavery clause in it. On the other hand it will be found to contain principles and purposes, entirely hostile to the existence of slavery.” While to some of his audience members these might have seemed like like bold claims, he backs them up. 

Douglass presents ample facts and data to support his argument. The text of the constitution is easy to fact check and he follows clear, concise logical structure throughout his arguments. He does not get carried away by pathos despite the emotional weight the topic carries for him. Rather, he lets pathos merely accentuate the powerful argumentation. Logos carries the crux of the argument; his logic is sound and his point is made. 

Susan B. Anthony: “Is it a crime for women to vote?” 

Susan B. Anthony is one of the most famous female public speakers in American History. A social reformer, anti-slavery advocate, and suffragette, she never hesitated to speak her mind. In 1972, she was arrested for “illegally” voting in the federal election. On a speaking tour before her trial, she delivered the speech “Is it a crime for women to vote?” Her speech, much like that of Douglass, uses citations from the U.S. constitution and laws to overturn a deeply entrenched public opinion.

One of her most persuasive methods is using logical extrapolation to show the absurdity of her opponent’s view. She argues that if the use of “he” in the constitution and other such documents signifies men to the exclusion of women, then women should be likewise excluded from taxation or criminal prosecution. “There is no she, or her, or hers, in the tax laws,” she observes. While amusing, this detail emphasizes a stark reality: those who forbid women to vote fail to follow their argument to its logical conclusion. 

It might not be immediately obvious, but with some softening of rhetoric, this tactic can be applicable to many situations in many different industries. For example, if you are trying to dissuade your audience from an unwise business strategy, you can extrapolate where that trend will lead them in one, five, or ten years. Or if you’re delivering a motivational speech that urges your audience to take a risk, you can present common hesitations and outline why they don’t hold up. While Susan B. Anthony’s suffragette activism was not effective in her lifetime, her rhetoric is without a doubt one of the best logos examples from the annals of American History. 

John F. Kennedy: “We Choose to Go to the Moon.”

While it’s hard to believe nowadays, the idea of going to the moon was a very unpopular one among many Americans. The 1960s were a time of massive social tension, as movements like the Civil Rights Movement transpired domestically while the Cold War loomed globally. People saw the space race as wasting loads of money on a petty battle for Moon real estate that ignored the needs of Americans. You can read more about opposition to the space race here

In this context, John F. Kennedy was hard pressed to rally the American people behind the banner of the moon. His address at Rice University in 1962 aims to quell their fears. He demonstrates with logos that going to the moon is not only in keeping with the American project, but also an important endeavor toward maintaining space as a terrain of “peaceful cooperation.” Going to the moon was not just a feather in the cap of American achievement. Rather it was  a statement to the world that the ideals of America and her allies, as opposed to those of the Soviet Union, should govern the “Great Unknown.”

To support his argument, JFK outlines the various feats that the U.S. has already accomplished in Space. He outlines the grim realities of the budget–but also the positive economic impact the program will have, especially in the town where he is speaking, Houston. By acknowledging truths both uncomfortable and exciting, he makes his case out in the open. JFK is a great example of a motivational speaker who uses logos while maintaining a stirring and heartening tone throughout. We recommend Kennedy’s inaugural address if you want to learn more from his great rhetoric!

Erin Baumgartner: “Big Data, Small Farms and a Tale of Two Tomatoes” 

Logos is incredibly important when you are distilling a unique topic for an audience who aren’t experts. If you cite complex data and statistics to listeners who aren’t data scientists and statisticians, you’ll lose them. Just as you can undermine logos by not including enough evidence, the same can happen by relying too much on numbers and not enough on clarifying them. Explaining the evidence and showing its application to the topic at hand is a difficult, but important skill. 

In her TEDx talk about data, farming, and food sourcing, Erin Baumgartner explains clearly and succinctly what data tells us about the failures of our modern food industry. To simplify her point, she focuses on two tomatoes. Data, she argues, helps us understand the difference between a tomato that has traveled 1600 miles to get to your plate and one that has only traveled 70. And data holds the answer to closing that gap and making it easier to access local, nutritious food. 

Since Baumgartner has a quantitative data perspective, she interweaves storytelling and humor as well as slides to help her audience keep up with her argument. Using slides with effective illustrations of data can be a great way to visually bolster the logos of your argument. We have several podcast episodes on how to use slides effectively–check out our favorites here, here, and here

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Niall Ferguson: “The Six Killer Apps of Prosperity” 

Niall Ferguson is a historian who has made a career of making complex historic and economic processes easier for the general public. In his TED talk, much like Baumgartner, Ferguson speaks about his niche expertise to non-experts. Unlike Baumgartner, Ferguson’s message is less about numbers and more about humanistic interpretive lens.

In his TEDx talk “The 6 Killer Apps of Prosperity”, he reviews six “apps” or institutions that have historically helped determine which nations or empires become prosperous. He discusses various well-known political theories and whether history has proven them right or wrong. He offers examples of how various nations have illustrated his own theory. And by using statistical graphs sparingly, he illustrates his points without overwhelming his listeners with data. Ferguson uses well-known historical events illuminated by his unique academic perspective to help his audience connect the dots of his argument 

Many speakers, regardless of their industry, are in a similar position to Ferguson and Baumgartner. At some point in your talk, you probably have to translate niche jargon into language the rest of us can understand. Whether you’re working with oodles of numbers or cerebral theories, a combination of simple examples and step-by-step argumentation will take you a long way toward mastering logos. 


This piece rounds out our discussion of Aristotle’s three rhetorical appeals with accompanying examples. As you can see, logos can be leveraged for a variety of causes. It requires both citing evidence and making that evidence easy to understand.That way, your audience can follow your argument to its logical conclusion. 

If you struggle with making your speeches truly persuasive, a good dose of logos might be all you need. Remember, we intend these examples to inspire you, not to make you worry about whether you measure up to the likes of JFK. Only you know how to tailor your specific message for your particular niche. With the inspiration of these logos examples from some of the greatest speakers of the past and present, you can start integrating more persuasive rhetoric into your own content and delivery. 


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