6.1 Overview of Logos

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.

6.2 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.

6.2.1 Deductive Reasoning

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

6.2.1.1 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.

6.2.1.2 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.

6.2.1.3 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

6.2.2 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.

6.2.2.1 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.

6.2.2.2 Weaknesses in Inductive Reasoning

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

6.2.2.2.1 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.

6.2.2.2.2 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.

6.2.2.3 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.

6.3 Logical Fallacies

Logical fallacies are statements or other kinds of representation that are misleading for one reason or the other. In the previous section, two have already been mentioned. Even though these are called logical fallacies, not all of them are exactly logical, so they are divided here by the persuasive appeals. The idea is that they are fallacies of persuasion and thinking. You will also notice that many of the fallacies overlap, and many examples might contain multiple fallacies at the same time. You may also note that some logical fallacies can double as legitimate persuasive techniques.

6.3.1 Fallacies of Logos

6.3.1.1 Fallacy of the Undistributed Middle

Description: The fallacy of the undistributed middle contains a term in the minor premise that mistakes an incidental characteristic of the general set of things in the major premise for the general set of things itself. In the case below, the minor premise is mistaking purple for the thing itself (grape/doughnut), rather than the characteristic shared by both the general set of things and the particular thing. In the end, if there are other things that can be purple, like royal robes, bruises, or wisteria, then purple is a characteristic and not a class.

Example:

• All grapes are purple
• This doughnut is purple.
• Therefore, this doughnut is a grape.

If the terms were switched, as below, then the syllogism is valid, if not true.

• All purple things are grapes.
• This doughnut is purple.
• Therefore, this doughnut is a grape.

Plug in variables, and it might make sense to those of you who are mathematically minded:

If A = The general class, C = an element that belongs to the general class, and B = a characteristic of the general class, then this syllogism is invalid:

• All A is B
• C is B.
• Therefore, C is A.

And this is valid:

• All A is B.
• C is A
• Therefore, C is B.

Other names for the fallacy of the undistributed middle include:  fallacy of the undistributed middle term, all-natural fallacy.

6.3.1.2 Hasty Generalization

Drawing a conclusion about a group of people, events, or phenomenon from a collection of insufficient or non-representative examples constitutes a Hasty Generalization. This  fallacy of inductive reasoning can be avoided by collecting numerous random examples.

• Since Homer, Lenny, and Smitty all approve of Skip’s Diner, it must be a great place to eat.
• Bears have been spotted at the Springfield dump three times in three years, so it is obvious we have a bear problem.
• The psychic at Colonel Tex’s Traveling Carnival saved Moe’s life by predicting Bart was going to drive Adolph Hitler’s car through the carnival tent at any moment, so she must be legit.

Other names for hasty generalization include:  hasty conclusion, jumping to conclusions.

6.3.1.3 Post Hoc, Ergo Propter Hoc

Post hoc, ergo propter hoc is a Latin phrase that means after which, therefore because of which. This fallacy assumes that because one thing happens after another, the thing that happened first was the cause.

• Lenny’s car ran out of gas right after the low fuel gauge started blinking, therefore the fuel gauge caused the car to run out of gas.
• Lisa put a stupid rock near the dump, and now there are no bears. The lack of bears must be due to the stupid rock.
• Right after Homer drank a Buzz Cola, Homer’s hair started falling out, so Buzz Cola must have caused his hair to fall out.

Other names for post hoc, ergo propter hoc include:  causal, false cause, clustering illusion.

6.3.1.4 Non-sequitur

Non sequitur just means does not follow. It isn’t strictly referring to cause and effect. It is actually referring to a conclusion that does not follow from the premise. Both the post hoc, ergo propter hoc and the fallacy of the undistributed middle are types of non sequitur.

• If you have mustard on your shirt, you should throw salt over your shoulder.
• The Springfield Glen Country Club should be granted tax-exempt status because of the large frog population.
• If Chewbacca lives on Endor, you must acquit.

Other names for non sequitur include: irrelevant reason, questionable premise, derailment, invalid inference.^[2]

6.3.1.5 Straw Man

Setting up a phony, weak, extreme, or ridiculous parody of an opponent’s argument specifically to make it easy to tear it down or make it sound absurd.

• Stating that Dr. Hibbard argues that testing causes the Osaka Flu, when his argument is actually that more testing will inevitably reveal more instances of the Osaka Flu.
• Stating that Mayor Quimby suggests that a new superhighway can be paid for by stealing money out of the worker’s pockets, when Mayor Quimby’s argument is that sales tax revenue could be used to fund a superhighway highway, which in turn could bring more revenue to Springfield.
• Stating that Lisa doesn’t want to eat meat because she thinks cows are people, when in fact she argues only that a plant based diet is better for her health, the environment, and is more humane to animals.

Other names for straw man include: straw person, straw figure.

6.3.1.6 False Dilemma

The presentation of an argument as if there are only two polarized choices with no middle ground , when in fact there are multiple alternatives.

• Either you are with us, or you are against us.
• Snitches get stitches.
• You can choose to lie about that email, or you can get fired.

Stating:

Other names for false dilemma include: either/or, false choice.

6.3.1.7 Slippery Slope

The suggestion that one small action will lead to a larger or more intense action, which will lead to an even larger or more intense action, and so on until some previously unimaginable consequence of a seemingly inconsequential action seems plausible

• If you give a mouse a cookie, he will ask for  a glass of milk, and then he will ask for a straw, and then he will ask for a mirror to avoid getting a milk mustache, until you are reading a story for him and hanging his pictures on the refrigerator as if he were your child.
• “We have to do something. Today he’s drinking blood, tomorrow he could be smoking!”^[3]
• “When your cable company puts you on hold, you get angry, you go blow off steam, when you blow off steam, accidents happen, when accidents happen, you get an eye patch, when you get an eye  patch, people think you’re tough, when people think you’re tough, they want to see how tough, and when people want to see how tough, you wake up in a roadside ditch.”^[4]

Other names for slippery slope include: exaggerated causal sequence, domino effect, overspreading, absurd extrapolation, the snowball argument, Pandora’s, dam burst.

6.3.1.8 Circular Argument

A claim that is supported by merely restating its premise in a different way.

• “The news is fake because so much of the news is fake.”
• Global warming is occurring, as evidenced by the fact that temperatures are rising globally.
• Bartman is better than than Fallout Boy, primarily because of his superiority.

Other names for circular argument include: begging the question, circulus in demonstrado.

6.3.1.9 Red Herring

An irrelevant argument, attempting to mislead and distract an audience by bringing up an unrelated but emotionally loaded issue.

• “Here, look at the silly monkey!”
• Oh yeah, well how did you get mustard on your shirt?
• “In regard to my several bankruptcies and recent indictment for corruption let’s be straight up about what’s really important: Terrorism!

Other names for red herring include: distraction.

6.3.1.10 Weak Analogy

Making a comparison of two purportedly analogous circumstances, events, or objects when the one is only similar in superficial or irrelevant ways to the other. Such analogies are rarely completely false, since it is easy to pick out similarities in almost anything, but they are weak if those similarities are lacking in quantity or relevance.

• Stealing cigarettes and selling them is like stealing bread to feed your family.
• Criticizing Mayor Quimby’s decision to vacation in the Bahamas during this crisis shouldn’t be considered free speech because it is dangerous, like yelling “fire” in a crowded theater.
• Shoplifting is a victimless crime, like punching someone in the dark.

Other names for weak analogy include: false analogy, spurious comparison, false equivalence.

6.3.1.11 Cherry Picking

Picking and choosing only some of the available evidence in order to present only points most favorable to your point of view. If someone knowingly chooses certain (favorable) pieces of information and conveniently ignores less favorable information, then the argument is not supported by all of the available research. This is one fallacy among several that falls into the category of selective attention. This fallacy thrives when there is a surplus of available data to choose from. It is commonly used to extol the virtues of public policy by showing positive data in places where the policy was implemented, while ignoring similar data in places where the policy was not implemented.

• Nine out of 10 people in Springfield are drunk right now, when all the people surveyed are in Moe’s Tavern. (in the First Church of Springfield, which is not mentioned, only 4 out of 10 people are drunk right now).
• An estimated 70% of car accidents occur within 15 miles of the driver’s home, according to a study by Progressive Insurance (of course they do – that is where people spend most of their time driving).
• There have been no bears sighted in Springfield since the Bear Patrol was implemented last month. (Also, there have been no bears sighted in Shelbyville during the same time period.)

Other names for cherry picking include: fallacy of exclusion, fallacy of omission, argument by selective observation, card-stacking.

6.3.2 Fallacies of Ethos

6.3.2.1 Bandwagon Effect

The suggestion that because a lot of people are doing something, you should do it too, or that because a lot of people think something, it must be true.

• It must be true if so many people are doing it.
• Everybody believes Abe murdered Vivienne St. Charmaine, so he must be guilty.^[5]
• McDonalds: “Over 99 Billion Served!”

Other names for bandwagon effect include: appeal to popularity, argumentum ad populum, argument to the people. common belief fallacy, argument from consensus.

6.3.2.2 Appeal to False Authority

Generally, the appeal to false authority is relying on the testimony of a person who is not qualified to speak to your argument. This is most often manifested by choosing someone who is popular, famous, or well-liked to validate, sponsor, or vouch for an idea or product, even if they are in no way an authority on it.

• Tom Cruise says that psychiatry is a pseudoscience.
• Marylin Monroe uses Lustre-Creme shampoo, so you should too.
• This actor portraying Charles Darwin does not consider my three-eyed fish to be a monster.

Other names for false authority include: appeal to popularity, argumentum ad populum, argument to the people. common belief fallacy, argument from consensus.

6.3.2.3 Ad Hominem

Ad Hominem means against the person. This fallacy involves attacking the character of the person making an argument rather than the argument itself. Note that there can be reverse ad-hominem as well, which means praising the character of only those who agree with you.

“If you want to believe a bunch of crazy promises about garbage men cleaning your gutters and waxing your car, then by all means, vote for this sleazy lunatic” – Sanitation Commissioner Patterson^[6]

• There’s nothing smart about you, Joe.
• My opponent is a Nazi-loving white supremacist.
• Other names for ad hominem include: ad mulierem, ad feminam, argument to character.
  

6.3.3 Fallacies of Pathos

6.3.3.1 Scare Tactics

Taking advantage of a emergent or deliberately-created crisis and its associated public shock, panic and chaos in order to impose an argument, action or solution that would be clearly unacceptable if carefully considered.

• “In this moment of crisis we can’t afford the luxury of criticizing or trying to second-guess my decisions when our very lives and freedom are in peril!”
• “This is about the safety of America!”
• “If you don’t shut up and do what I say we’re all gonna die!

Other names for scare tactics include: appeal to fear; the bogeyman fallacy.

6.3.3.2 Affective Fallacy

A claim that one’s emotions, urges or “feelings” are innate and in every case self-validating, autonomous, and above any human intent or act of will (one’s own or others’), and are thus immune to challenge or criticism.

• Follow your heart
• I feel it in my soul, so it must be true.
• If you eat whatever you desire at the moment, you will be healthy.

Other names for affective fallacy include: romantic fallacy, follow your heart.