Logos Definition

What is logos? Here’s a quick and simple definition:

Logos, along with ethos and pathos, is one of the three "modes of persuasion" in rhetoric (the art of effective speaking or writing). Logos is an argument that appeals to an audience's sense of logic or reason. For example, when a speaker cites scientific data, methodically walks through the line of reasoning behind their argument, or precisely recounts historical events relevant to their argument, he or she is using logos.

Some additional key details about logos:

  • Aristotle defined logos as the "proof, or apparent proof, provided by the words of the speech itself." In other words, logos rests in the actual written content of an argument.
  • The three "modes of persuasion"—pathos, logos, and ethos—were originally defined by Aristotle.
  • In contrast to logos's appeal to reason, ethos is an appeal to the audience based on the speaker's authority, while pathos is an appeal to the audience 's emotions.
  • Data, facts, statistics, test results, and surveys can all strengthen the logos of a presentation.

How to Pronounce Logos

Here's how to pronounce logos: loh-gos

Logos and Different Types of Proof

While it's easy to spot a speaker using logos when he or she presents statistics or research results, numerical data is only one form that logos can take. Logos is any statement, sentence, or argument that attempts to persuade using facts, and these facts need not be the result of long research. "The facts" of an argument can also be drawn from the speaker's own life or from the world at large, and presenting these examples to support one's view is also a form of logos. Take this example from Sojourner Truth's "Ain't I a Woman?" speech in support of women's rights:

That man over there says that women need to be helped into carriages, and lifted over ditches, and to have the best place everywhere. Nobody ever helps me into carriages, or over mud-puddles, or gives me any best place! And ain't I a woman? Look at me! Look at my arm! I have ploughed and planted, and gathered into barns, and no man could head me! And ain't I a woman?

Truth points to her own strength, as well as to the fact that she can perform physically tiring tasks just as well as a man, as proof of equality between the sexes: she's still appealing to the audience's reason, but instead of presenting abstract truths about reality or numerical evidence, she's presenting the facts of her own experience as evidence. In this case, the logic of the argument is anecdotal (meaning it's derived from a handful of personal experiences) rather than purely theoretical, but it goes to show that logos doesn't have to be dry and clinical just because it's concerned with proving something logically.

Logos: Proof vs. Apparent Proof

Not all speakers who use logos can be blindly trusted. As Aristotle specifies in his definition of the term, logos can be "proof, or apparent proof." A speaker may present facts, figures, and research data simply to show that he or she has "done their homework," in an effort to attain the degree of credibility that is often automatically attributed to scientific studies and evidence-driven arguments. Or a speaker might present facts in a way that is wholly or partially misrepresentative, using those facts (and, by extension, logos) to make a claim that feels credible while actually arguing something that is untrue. Yet another factor that can cause a speech or text to have the appearance of providing proof is the use of overlong words and technical language—but just because someone sounds smart doesn't mean their argument stands to reason.

Even if the facts have been manipulated, any argument that relies on or even just claims to rely on "facts" to appeal to a listener's reason is still an example of logos. Put another way: logos is not about using facts correctly or accurately, it's about using facts in any way to influence an audience.

Logos Examples

Examples of Logos in Literature

While Aristotle defined the term logos with public speaking in mind, there are many examples of logos in literature. Generally, logos appears in literature when characters argue or attempt to convince one another that something is true. The degree to which characters use logos-driven arguments can also provide important insight into their personalities and motives.

Logos in Shakespeare's Othello

In Othello, Iago plots to bring about the downfall of his captain, Othello. Iago engineers a series of events that makes it look like Othello’s wife, Desdemona, is cheating on him. Suspicion of his wife’s infidelity tortures Othello, who only recently eloped with Desdemona against her father’s wishes. In this passage from Act 3, Scene 3, Iago manipulates Othello by means of logos. Iago "warns" Othello not to succumb to paranoia even as he fans the flames of that paranoia:

Oh, beware, my lord, of jealousy!
It is the green-eyed monster which doth mock
The meat it feeds on…..
Who, certain of his fate, loves not his wronger,
But, oh, what damnèd minutes tells he o’er
Who dotes, yet doubts— suspects, yet soundly loves…
She did deceive her father, marrying you…
She loved them most….
I humbly do beseech you of your pardon
For too much loving you….

Iago here lectures Othello on the abstract dangers of jealousy, but then goes on to use reason and deduction to suggest that, because Desdemona deceived her beloved father by marrying Othello, she'd probably be willing to deceive Othello, too.

Logos in Don DeLillo's White Noise

In this passage from Part 2 of Don Delillo’s novel White Noise, Jack Gladney and his son Heinrich gaze through binoculars at an Airborne Toxic Event—or cloud of poison gas—that has just hit their town. Jack, in denial, tries to reassure his son that the cloud won’t blow in their direction and that there’s no cause for alarm. Heinrich disagrees:

"What do you think?" he said.
"It's still hanging there. Looks rooted to the spot."
"So you're saying you don't think it'll come this way."
"I can tell by your voice that you know something I don't know."
"Do you think it'll come this way or not?"
"You want me to say it won't come this way in a million years. Then you'll attack with your little fistful of data. Come on, tell me what they said on the radio while I was out there."
"It doesn't cause nausea, vomiting, shortness of breath, like they said before."
"What does it cause?"
"Heart palpitations and a sense of deja vu."
"Deja vu?"

"It affects the false part of the human memory or whatever. That's not all. They're not calling it the black billowing cloud anymore."
"What are they calling it?"
He looked at me carefully.

"The airborne toxic event." ...
"These things are not important. The important thing is location. It's there, we're here."
"A large air mass is moving down from Canada," he said evenly.
"I already knew that."
"That doesn't mean it's not important."
"Maybe it is, maybe it isn't. Depends."

Jack tries to reassure himself and his family that the situation isn’t serious. Heinrich tries to counter his father’s irrational, fear-driven response to the catastrophe with his "fistful of data": information he's learned in school from a science video on toxic waste, as well as reports about the disaster that he heard on the radio. He presents the facts so that his father can’t ignore them, thereby strengthening the logos of his argument that the situation is serious and the cloud will come their way. In this particular example, the lack of logos in Jack's argument reveals a lot about his character—even though Jack is a tenured college professor, strong emotions and fear for his own mortality often drive his behavior and speech.

Logos in Harper Lee's To Kill a Mockingbird

In this example from To Kill a Mockingbird, lawyer Atticus Finch uses logos to argue on behalf of a black defendant, Tom Robinson, who stands accused of raping a white woman.

"The state has not produced one iota of medical evidence to the effect that the crime Tom Robinson is charged with ever took place. It has relied instead upon the testimony of two witnesses whose evidence has not only been called into serious question on cross-examination, but has been flatly contradicted by the defendant. The defendant is not guilty, but somebody in this courtroom is."

The logos in this case lies in Atticus' emphasis on the facts of the case, or rather, the fact that there are no facts in the case against Tom. He temporarily ignores questions of racial justice and emotional trauma so that the jury can look clearly at the body of evidence available to them. In short, he appeals to the jury's reason.

Logos in Robert M. Pirsig's Zen and the Art of Motorcycle Maintenance

In Zen and the Art of Motorcycle Maintenance, the narrator takes a cross-country motorcycle trip with his son Chris, and their two friends John and Sylvia. When Chris tells the group in Chapter 3 that his friend Tom White Bear believes in ghosts, the narrator tries to explain that scientific principles only exist in our heads, and therefore are actually modern man's equivalent of ghosts:

"Modern man has his ghosts and spirits too, you know."
"Oh, the laws of physics and of logic...the number system...the principle of algebraic substitution. These are ghosts. We just believe in them so thoroughly they seem real."
"They seem real to me," John says.
"I don't get it," says Chris.
So I go on. "For example, it seems completely natural to presume that gravitation and the law of gravitation existed before Isaac Newton. It would sound nutty to think that until the seventeenth century there was no gravity."
"Of course"
"So when did this law start? Has it always existed?...What I'm driving at is the notion that before the beginning of the earth, before the sun and the stars were formed, before the primal generation of anything, the law of gravity existed."
"Sitting there, having no mass of its own, no energy of its own, not in anyone's mind because there wasn't anyone, not in space because there was no space either, not anywhere—this law of gravity still existed?"
Now John seems not so sure.
"If the law of gravity existed," I say, "I honestly don't know what a thing has to do to be nonexistent. It seems to me that law of gravity has passed every test of nonexistence there is...And yet it is still 'common sense' to believe that it existed."
"I guess I'd have to think about it."
"Well, I predict that if you think about it long enough you will find yourself going round and round and round and round until you finally reach only one possible, rational, intelligent conclusion. The law of gravity and gravity itself did not exist before Isaac Newton. No other conclusion makes sense. And what that means...is that that law of gravity exists nowhere except in people's heads! It's a ghost!"

The narrator uses logos in his discourse on scientific concepts by presenting his audience with an example—gravity—and asking them to consider their own experience of gravity as empirical evidence in support of his argument. He urges his friends to come to a "rational, intelligent conclusion" about the concept of gravity, instead of relying on conventional wisdom and unexamined assumptions.

Logos in Political Speeches

Politicians frequently use logos, often by citing statistics or examples, to persuade their listeners of the success or failure of policies, politicians, and ideologies.

Logos in Barack Obama's 2015 State of the Union Address

In this example, Obama cites historical precedent and economic data from past years to strengthen his argument that recent progress has been substantial and that the nation's economy is in good health:

But tonight, we turn the page. Tonight, after a breakthrough year for America, our economy is growing and creating jobs at the fastest pace since 1999. Our unemployment rate is now lower than it was before the financial crisis. More of our kids are graduating than ever before. More of our people are insured than ever before. And we are as free from the grip of foreign oil as we’ve been in almost 30 years.

Logos in Ronald Reagan's 1987 "Tear Down this Wall" Speech

In this speech, Reagan intends for his comparison between the poverty of East Berlin—controlled by the Communists—and the prosperity of Democratic West Berlin to serve as hard evidence supporting the economic superiority of Western capitalism. The way he uses specific details about the physical landscape of West Berlin as proof of Western capitalist economic superiority is a form of logos:

Where four decades ago there was rubble, today in West Berlin there is the greatest industrial output of any city in Germany--busy office blocks, fine homes and apartments, proud avenues, and the spreading lawns of parkland. Where a city's culture seemed to have been destroyed, today there are two great universities, orchestras and an opera, countless theaters, and museums. Where there was want, today there's abundance--food, clothing, automobiles--the wonderful goods of the Ku'damm. From devastation, from utter ruin, you Berliners have, in freedom, rebuilt a city that once again ranks as one of the greatest on earth...In the 1950s, Khrushchev [leader of the communist Soviet Union] predicted: "We will bury you." But in the West today, we see a free world that has achieved a level of prosperity and well-being unprecedented in all human history. In the Communist world, we see failure, technological backwardness, declining standards of health, even want of the most basic kind—too little food. Even today, the Soviet Union still cannot feed itself. After these four decades, then, there stands before the entire world one great and inescapable conclusion: Freedom leads to prosperity. Freedom replaces the ancient hatreds among the nations with comity and peace. Freedom is the victor.

Why Do Writers Use Logos?

It's important to note that the three modes of persuasion often mutually reinforce one another. They don't have to be used in isolation from one other, and the same sentence may even include examples of all three. While logos is different from both ethos (an appeal to the audience based on the speaker's authority) and pathos (an appeal to the audience's emotions), the use of logos can serve as a strong complement to the use of ethos and/or pathos—and vice versa.

For instance, if a politician lists the number of casualties in a war, or rattles off statistics relating to a national issue, these facts may well appeal to the audience's emotions as well as their intellect, thereby strengthening pathos as well as logos as elements in the speech. Consider this passage from Michelle Obama's 2015 speech at The Partnership for a Healthier America Summit, in which she updates listeners on the success of her Let's Move! project for improving children's nutrition:

I mean, just think about what our work together means for a child born today. Maybe that child will be one of the 1.6 million kids attending healthier daycare centers where fruits and vegetables have replaced cookies and juice. And when that child starts school, maybe she’ll be one of the over 30 million kids eating the healthier school lunches that we fought for. Maybe she’ll be one of the 2 million kids with a Let’s Move! salad bar in her school, or one of the nearly 9 million kids in Let’s Move! Active Schools who are getting 60 minutes of physical activity a day, or one of the 5 million kids soon attending healthier after-school programs.

While Obama includes statistics to persuade her audience that Let's Move! has been a success (logos), she's also using those facts and figures to stir up enthusiasm for her cause (pathos).

Other Helpful Logos Resources

  • The Wikipedia Page on Logos: A detailed explanation and history of the term.
  • The Dictionary Definition of Logos: A definition encompassing the different meanings of the word logos.
  • Logos on Youtube: A video from TED-Ed about the three modes of persuasion.