The most straightforward English translation of logos is word. We think of logic, of course, and that is reasonable, since a reason is a secondary, or even synonymous translation. Logos is the use of words to reason. Quintillian says that logos in rhetoric is a method of “proving what is not certain by means of what is certain.”^[1] All logos begins with a premise, and every word, it could be argued, is a premise. For instance, when someone says “I see a dog” to you they are depending on the premise that when you both agree on what a dog is. The word itself, dog, becomes the premise, or known entity, upon which the claim “I see a dog”  is built.

Those who opposed the Sophists felt that logos should be the primary appeal because it always led to the truth, whereas ethos, pathos, and kairos could all be used effectively to deceive. And while pathos is a very good tool for getting people to act, its effect lasts only as long as the emotion lasts. Logos, however, doesn’t change over time – what is logically sound now will still be logically sound twenty years from now, just like two plus two will always equal four.

Types of Reasoning

One can reason from absolute certainties, or one can reason from probabilities. Reasoning from a general truth to a particular  truth is called deductive reasoning, while reasoning from a particular truth to a more general truth is called inductive reasoning. The conclusions from deductive reasoning are absolutely certain as long as the general premises are unconditionally true, while the conclusions from inductive reasoning can only be expressed in probabilities.

Deductive Reasoning

This is also sometimes called syllogistic reasoning, and the deductive argument is called a syllogism.

The Syllogism

Deductive reasoning starts from a general premise that is universally assumed to be true. This is referred to as the major premise.

The minor premise refers to a particular truth, but that is also assumed to be true.

The conclusion in a deductive argument asserts that what is true of the class of things listed in the major premise is also true of the particular thing that is part of that class.

Here is the classic example of deductive reasoning:

• Major Premise: Socrates is a man.
• Minor Premise: Socrates is mortal.
• Conclusion: Therefore, Socrates is mortal.

Here is the updated, morbid version:

• Major Premise: All people die.
• Minor Premise: Montgomery Burns is a person.
• Conclusion: Therefore, Montgomery Burns is going to die.

Validity

A deductive argument can be valid whether the first two premises are true or false. Deductive arguments are valid only if it is impossible for the premises to be true and the conclusion to be false. For example, if Montgomery Burns is actually an alien and not a person, then the statement “Montgomery Burns is a person” in the above syllogism is false, making the conclusion false, but still valid.

Valid Argument:

• Major Premise: All aliens live forever.
• Minor Premise: Montgomery Burns is an alien.
• Conclusion: Therefore, Montgomery Burns is going to live forever.

Invalid Argument

• Major Premise: All aliens live forever.
• Minor Premise: Montgomery Burns is going to live forever.
• Conclusion: Therefore, Montgomery Burns is an alien.

Even assuming the premises are true, this is still an invalid argument and a logical fallacy called the “undistributed middle term.” Here is an easier one to swallow, but still invalid:

• Major Premise: All nice people have dogs.
• Minor Premise: Montgomery Burns has a dog.
• Conclusion: Therefore, Montgomery Burns is a nice person.

This is invalid because even if all nice people have dogs, other kinds of people also have dogs, including mean people.

Truth

The conclusion in a deductive argument is only true if both premises are true and the argument is valid.

The conclusion in a deductive argument is always either true or false. It can never be partially true

Inductive Reasoning

Unlike deductive reasoning, inductive reasoning moves from the specific to the general. The conclusion is never certain, and can only be expressed in terms of probability. Inductive reasoning uses a series of examples to suggest that what holds true for these few examples holds true for the class of things each example belongs to.

Take the class of business owners in Springfield, and consider the following specific examples of business owners in Springfield:

• Krusty the Clown pays city taxes.
• Artie Ziff pays city taxes.
• Apu Nahasepeemapetilon pays city taxes.
• Moe Szyslak pays city taxes.

Can it be said, for certain, on the basis of these examples, that Herbert Powell, owner and CEO of Powell Motors, pays city taxes? Probably not, but if most business owners in Springfield pay city taxes, it could be said that Herbert Powell probably pays city taxes. Usually inductive reasoning will be expressed in percentages of probabilities, but the logic still attempts to prove the unknown from the known, just as Quintilian suggested it should. If, for instance it is known that 93% of business owners in Springfield pay city taxes, but we have not yet verified that Herbert Powell pays city taxes, we can still say there is a 93% chance that he does.

Inductive Premises

Interestingly, inductive arguments can be used as premises in deductive arguments, with the caveat that the probability in the conclusion can never exceed the probability expressed in the major premise. Here is how the above inductive conclusion would fit into a syllogism:

• Ninety percent of business owners in Springfield pay city tax.
• Ned Flanders is a business owner in Springfield.
• Therefore, there is a 90% probability that Ned Flanders pays city tax.

It gets fuzzier when words are used to express probabilities rather than hard numbers:

• Most business owners in Springfield pay city tax.
• Montgomery Burns is a business owner in Springfield.
• Therefore, Montgomery Burns probably pays city tax.

Weaknesses in Inductive Reasoning

Either of the weaknesses below can result in the hasty generalization fallacy.

Insufficient Sample Size

In most cases, just a few examples of some phenomenon or event are not enough to generalize to a larger set or population. What constitutes a sufficient number of examples depends on the size of the set or population you hope to generalize to. There is a statistical formula for figuring out how big of a sample you need to generalize to a specific population or set with a particular confidence level with a specific margin of error with a given standard deviation. As a rule of thumb, though, you can make inferences about 1000 people on the basis of what you know to be true of about 100. Of course, the smaller the numbers, the more sensitive they are to errors, so you definitely cannot generalize what you know about two people to twenty people.

Insufficient Sample Representativeness

The other problem with generalizing is that when the group you are collecting your examples from is very different than the group you are generalizing to then the comparison might not be as valid. For example, if 90% of all the skateboarders you know, all of which are over 40, don’t tie their shoes, and on that basis you predict that 90% of skateboarders under 20 don’t tie their shoes, then your inductive argument is flawed.

Extrinsic Proofs

Extrinsic proofs are proofs that exist already in the real world. They include examples, testimony, observations, survey results, statistics, and other forms of data. Because they concern particulars and not universals, extrinsic truths are much more likely to appear in inductive reasoning.

Pathos

Pathos is the use of emotion to persuade an audience. The effective use of pathos depends critically on a keen understanding of the writer’s audience and the emotions they are likely to be experiencing at the time of the communicative event. More importantly, the writer should be aware of what triggers the audience might have that are likely to induce states of emotion that are liable to cause them to act or think as a she desires. Thus it is important to know both the existing and possible range of emotions for a particular audience. College students, when asked to describe their current or recent emotional states, will typically come up with a list that looks something like this: happy, sad, stressed, anxious, hopeful, afraid, tired, hungry, Notice first that this list includes some items that are more biological than emotional, namely tired and hungry. For most rhetorical purposes, many biological states and emotional states are fairly interchangeable because 1) Certain emotional states can induce certain biological states, and 2) Certain biological states can induce certain emotional states, and 3) Some words like agitated or depressed actually describe states that are in part physical and in part mental. This is why it could be argued that water bottle advertisements use pathos by appealing to the thirst of their audience. We can posit that thirst is a biological need that causes a desire that can only be fulfilled by the kind of clean, natural water these bottled water advertisements seem to be offering. Or consider anger, which is usually accompanied by physiological responses like increased heart rate, blood pressure, respiration and body temperature. In most cases a biological need can be clearly associated with one or more attendant emotional needs. For rhetorical purposes, biological and emotional states are very similar, and with a few reservations can be considered under the heading of pathos.

Push/Pull Methods

Two strategies can be adopted for utilizing pathos, which I call the pull method and the push method. The pull method utilizes the existing emotional state of the audience to convince them to take a particular action or buy into a particular idea. It assumes that most undesirable emotional states seek resolution to some more desirable state. In other words, if you have an action or idea you want a sad audience to adopt, stress how your suggested action or idea will make them happy, or if you know your audience is stressed, show how taking the action you recommend can help them attain peace of mind, and so on. The push method, on the other hand, induces an emotion, then subsequently offers a solution. For example, showing or telling about injustices can make an audience angry, and the solution most sought after from an angry audience is revenge or justice, so that once a writer induces anger in an audience, they can proceed to offer an action or idea that resolves that anger by showing how that action or idea provides a path to revenge, or in more positive terms, to justice.

Kairotic Method

The kairotic method may make more sense once you have read about kairos, but essentially, it is adjusting the timing or introduction of an idea, concept, or call to action to coincide with a particular emotional state in an attempt to create an association between the two. For example, the appearance of a villain in a drama is often accompanied by dark or scary music, so the villain is associated with unpleasant emotions. Note that there doesn’t have to be a logical connection between the emotion and the idea or concept – they just have to occur at the same time to create an association that isn’t necessarily rational. For an example of how Budweiser uses the kairotic method to associate their brand with feelings of happiness and joy, recall the famous commercial that has a puppy getting lost, getting into dangerous situations, and returning home. Right at the moment the audience is about to cry, the Budweiser logo takes over the screen. There is no logical connection here between the Budweiser logo and the joy the audience feels when the puppy returns home, but the writer’s hope the audience will forever associate that feeling with their product just because the two events happened at the same time.

Ethos