"Logic is the anatomy of thought."
– John Locke
"Logos" is the appeal to logic. Logos isn't logic like the formal logic in math, philosophy, or even computer science; it is the consistency and clarity of an argument as well as the logic of evidence and reasons.
In formal logic, in abstraction, the following is the case: if A is true and B is true and A is an instance of B, then the repercussions of B will always be true. The problem, however, is that this kind of logic doesn't work for real-life situations. This is where argument comes into play. Formal logic would say that speeding, for example, is a violation of traffic laws. A repercussion of violating a traffic law is a ticket; therefore, every person who speeds gets a ticket. However, in real life, not in abstract theory, things aren't that cut and dried. Most people would not agree that all speeders, in every circumstance, should receive a ticket. In an argument about a real-life situation, the audience needs particulars to make their decisions. Sometimes there's an exception. Why was that person speeding? Well, if an eighteen-year-old is speeding to show off for his friends, then yes, most people would agree that he deserves a ticket. However, if a man is driving his pregnant wife to the hospital, then maybe he does not deserve the ticket. One could, and probably would, make the argument that he should not get a ticket.
Let's examine how the appeal to logic would work in an argument for the speeding father-to-be.
Because arguments are based on values and beliefs as well as facts and evidence, it is logical that the argument must coincide with accepted values and beliefs. The enthymeme is the foundation of every argument. Enthymemes have three parts: the claim, the reason, and the unstated assumption that is provided by the audience. All three of these things must make sense to your audience in order for your argument to be considered logical. The claim of an argument for the father-to-be could be something like, "This man should not get a speeding ticket." That's it. The claim is pretty simple. It is your educated opinion on the matter. The reason would be something like "because his wife is in labor in the backseat." So the two stated parts of your enthymeme would be, "This man should not get a speeding ticket because his wife is in labor in the backseat." Now, this seems obviously logical to us; however, what is our underlying value, our unstated assumption about this argument? Most of us would probably agree that a hospital is a better place to give birth in than a backseat. That is the third part of the enthymeme. Your audience must agree that your assumption is true in order for your argument to be considered logical. If your readers don't have the same assumption, they are not going to see your logic. You must find an enthymeme that works for your audience. The pregnant wife enthymeme is fairly easy to see. In more volatile claims and reasons, the unstated assumptions can be trickier to identify and work out with your audience.
Reasons like "because his wife is in labor" are motivations for the driver's actions, not evidence. Most audiences need facts. Evidence is the facts. Both reasons and evidence are used in an appeal to logic; however, reasons cannot be your only support. Evidence as to why the man should speed might include studies about the problems with births in difficult or dangerous circumstances, interviews with women who have given birth in automobiles, and infant mortality rates for births that do not occur in hospitals. As you can see, there are many different kinds of evidence you could provide for this argument.
Consistency means not changing the unstated or stated rules governing your argument. Consistency is essential to logic. Let us continue with the speeding example. If, for instance, you are arguing that the infant mortality rate is too high for babies born outside the hospital and that the father is required to speed for the safety of his unborn child, then you may not want to include evidence of the high infant mortality rate in car crashes. Although this information may be part of the infant mortality rate, it goes against the underlying assumption that speeding is acceptable because of the high risk of harming the baby if it is born in the backseat.
So why should you care about logos? In your own writing, logos is important because it appeals to your readers' intellects. It makes you readers feel smart. Logos is the part of the argument where you treat your audience like purely rational, "only the facts, ma'am" kind of people. Also, gaps, leaps, and inconsistencies in logic, no matter how well developed the other appeals may be, can tear apart an argument in short order. This is the same reason you cannot ignore logos in others' arguments either. All the appeals are linked together; for instance, if you use as evidence an article that has leaps in logic, or relies only on authority and emotions, this article could damage your own ethos as an author. It is important to remember that all three appeals must be well developed and work together to make a good argument.
As you now know, logos can be defined as a writer's or speaker's attempt to appeal to the logic or reason of her audience. Let's look at some examples of logos that you might commonly find when reading texts of various media:
- Statistics. When a writer employs data or statistics within a text, you can probably assume that he or she is attempting to appeal to the logic and reason of the reader. For example, an argument in favor of keeping abortion legal may cite the May 2011 Pew Research poll that found 54 percent of Americans in favor of legal abortion. This figure makes a logical argument: abortion should be legal because the majority of Americans support it, and in a democracy, the majority makes the decisions.
- Causal statements.When you see an "if-then" statement, with credible supporting evidence, the writer is likely appealing to your reason. Consider an argument about lowering the drinking age from 21 to 18: a writer might suggest that, if the legal drinking age were 18, then people between 18 and 21 would be less likely to drive under the influence. If the writer offers evidence that the reason that some between the ages of 18 and 21 drive drunk is that they fear calling a friend or parent because they have illegally ingested alcohol, then this causal statement would be an appeal to a reader's sense of reason.
- Relevant examples or other evidence. You might begin to think about logos as evidence that doesn't involve an appeal to your emotions. Even expert testimony, which would certainly be an example of ethos, also could be an example of logos, depending on its content. For example, in a discussion about recent cuts in education funding, a statement from the Hillsborough County, Florida, superintendent would be an appeal to authority. But if that statement contained a discussion of the number of teachers and classes that would have to be cut if the state were to reduce the district's funding, the statement from the superintendent could also be an appeal to logic.
Aristotle’s "modes for persuasion" – otherwise known as rhetorical appeals – are known by the names of ethos, pathos, and logos. They are means of persuading others to believe a particular point of view. They are often used in speech writing and advertising to sway the audience.
Meaning of Ethos, Pathos and Logos
Aristotle used these three terms to explain how rhetoric works:
"Of the modes of persuasion furnished by the spoken word there are three kinds. The first kind depends on the personal character of the speaker [ethos]; the second on putting the audience into a certain frame of mind [pathos]; the third on the proof, or apparent proof, provided by the words of the speech itself [logos]. Persuasion is achieved by the speaker’s personal character when the speech is so spoken as to make us think him credible."
Ethos (sometimes referred to as an appeal to ethics), then, is used as a means of convincing an audience via the authority or credibility of the persuader, be it a notable or experienced figure in the field or even a popular celebrity.
Pathos (appeal to emotion) is a way of convincing an audience of an argument by creating an emotional response to an impassioned plea or a convincing story.
Logos (appeal to logic) is a way of persuading an audience with reason, using facts and figures.
Examples of Ethos, Pathos and Logos
Here are some examples of using ethos, pathos, and logos to persuade.
- "As a doctor, I am qualified to tell you that this course of treatment will likely generate the best results."
- "My three decades of experience in public service, my tireless commitment to the people of this community, and my willingness to reach across the aisle and cooperate with the opposition, make me the ideal candidate for your mayor."
- "The veterinarian says that a German Shepherd will be the perfect match for our active lifestyle."
- "If my years as a Marine taught me anything, it’s that caution is the best policy in this sort of situation."
- "You know me – I’ve taught Sunday School at your church for years, babysat your children, and served as a playground director for many summers – so you know I can run your preschool."
- "Our expertise in roofing contracting is evidenced not only by our 50 years in the business and our staff of qualified technicians, but in the decades of satisfied customers who have come to expect nothing but the best."
- "He is a forensics and ballistics expert for the federal government – if anyone’s qualified to determine the murder weapon, it’s him."
- "Based on the dozens of archaeological expeditions I’ve made all over the world, I am confident that those potsherds are Mesopotamian in origin."
- "If my age doesn’t convince you that I know what I'm talking about, at least consider that I am your grandfather and I only want the best for you."
- "Doctors all over the world recommend this type of treatment."
- "If you’re still unsure, please consider that my advanced degree and field work speak for themselves."
- "If we don’t move soon, we’re all going to die! Can’t you see how dangerous it would be to stay?"
- "I’m not just invested in this community – I love every building, every business, every hard-working member of this town."
- "There’s no price that can be placed on peace of mind. Our advanced security systems will protect the well-being of your family so that you can sleep soundly at night."
- "Where would we be without this tradition? Ever since our forefathers landed at Plymouth Rock, we’ve celebrated Thanksgiving without fail, making more than cherished recipes. We’ve made memories."
- "They’ve worked against everything we’ve worked so hard to build, and they don’t care who gets hurt in the process. Make no mistake, they’re the enemy, and they won’t stop until we’re all destroyed."
- "Don’t be the last person on the block to have their lawn treated – you don’t want to be the laughing stock of your community!"
- "You should consider another route if you leave later. I heard that that street is far more dangerous and ominous at night than during the daytime."
- "You’ll make the right decision because you have something that not many people do: you have heart."
- "After years of this type of disrespect from your boss, countless hours wasted, birthdays missed… it’s time that you took a stand."
- "Better men than us have fought and died to preserve this great nation. Now is our turn to return the favor. For God and country, gentlemen!"
- "You will never be satisfied in life if you don’t seize this opportunity. Do you want to live the rest of your years yearning to know what would have happened if you just jumped when you had the chance?"
- "The data is perfectly clear: this investment has consistently turned a profit year-over-year, even in spite of market declines in other areas."
- "Ladies and gentlemen of the jury: we have not only the fingerprints, the lack of an alibi, a clear motive, and an expressed desire to commit the robbery… We also have video of the suspect breaking in. The case could not be more open and shut."
- "It’s a matter of common sense that people deserve to be treated equally. The Constitution calls it ‘self-evident.’ Why, then, should I have been denied a seat because of my disability?"
- "More than one hundred peer-reviewed studies have been conducted over the past decade, and none of them suggests that this is an effective treatment for hair loss."
- "History has shown time and again that absolute power corrupts absolutely."
- "Private demand for the product has tapered off for the past three years, and this year’s sales figures are at an all-time low. It’s time to research other options."
- "The algorithms have been run in a thousand different ways, and the math continues to check out."
- "You won't find any deer along this road. In 25 years of driving the same route, I haven’t seen a single one."
- "He has a track record of success with this company, culminating in some of our most acclaimed architecture to date and earning us Firm of the Year nine times in a row."
- "Research compiled by analysts from NASA, as well as organizations from five other nations with space programs, suggests that a moon colony is viable with international support."
Understanding the different aspects of rhetoric will make you more aware of what goes into creating a persuasive argument. The examples above should also help you construct your own arguments or appeals.