Critical Thinking: Common Informal Fallacies, Part 1


UnknownWhen most people seek a college education, it is usually with the intention of acquiring a specific skill so they can then get a financially rewarding job.  This, I think, is a somewhat misguided use of the college experience, however. Many of the skills people end up using in their career are learned on the job. The foremost value of education is to teach someone how to think. Armed with the tools of critical thinking, we can more easily discern the true from the false from the unknown and then make better decisions. Decisions as specific as what to do in the doctor’s office or the voting booth, or as broad as what you value and what profession would give your life meaning as well as make it financially solvent.

Deductive and Inductive Reasoning; Formal and Informal Arguments

There are two basic thinking modes humans use to arrive at a conclusion. When a person engages in deductive reasoning, they begin with premises, or things they think they already know. They then combine them logically to make new conclusions that follow necessarily from these premises. The conclusion does not add any new real information to the argument; all the information in the conclusion was already contained in the premises, and the conclusion is necessarily so.  This kind of reasoning is used in a limited, though very important way. One example is in science where some of the new information is contained in new premises and we are trying to understand the ramifications of our experiment. Another might be in law where we try to reach conclusions from new evidence. Coming to conclusions deductively is a question of formal logic. Formal logic tells us if the scientific or legal argument is valid. Here is an example of deductive reasoning in a piece of formal logic:

  1. All the exams from that class show evidence of cheating
  2. John took an exam in that class.
  3. John cheated.

Most of the thinking we do in our daily lives is inductive in nature. In this case, the conclusion contains more information than was contained in the premises. Also, here the conclusion hopefully has a high probability of being true, but it isn’t necessarily so. While deductive arguments are either valid or invalid, inductive arguments are either strong or weak; good or bad. Here is a classic example of an informal argument using inductive logic:

  1. The sun has risen every morning since long before man can remember
  2. Therefore, the sun will rise tomorrow.

Here, the conclusion (2) adds new information because nothing was said in (1) about the future. It seems to be a good argument, but is it necessarily so? No. The doomsday survivalists and Mayan Oracles could be right and an asteroid could hit the earth while we sleep.  But is it a strong argument? I’d say so. The kind of argument you might want to make a decision about in your real life.

Fallacies of formal logic have their interest and long histories, but fallacies of informal logic and inductive reasoning play a great part of our everyday lives. They create mayhem in our personal decisions and public policy. In this post I would like to go over some of the most egregious examples. Just understanding some of these will make you less easily swayed by advertising and public debate and give you ammunition when the doctor is telling you something that doesn’t sound quite right.

Arguments (here, inductive reasoning that leads to a conclusion), need three things to make them “strong,” “persuasive,” or “good.” First, they need to represent the facts correctly; those that do not are committing “fallacies of presumption”. Second, they must use language clearly so that the argument is also clear; those that don’t do this are “fallacies of ambiguity.” Third, the conclusion must follow directly from the premises in a logical way so that the argument is valid; errors of this nature are “fallacies of irrelevance.”

Fallacies of Presumption: Misusing the Facts

The first way we can misuse the facts is by distorting them. Here are three fallacies that do this.

Correlation vs. Causation (also know as “false cause” or in Latin “cum hoc ergo propter hoc”)

When two things occur at the same time or together in space they are correlated with each other and we often then assume that one is causing the other.  This is a bad assumption, and it is my personal pet peeve; the Grandaddy of Logical Fallacies to me, and so I placed it first in my post.

Example from the nightly news: “A study by the XYZ Teeth of America Association has just completed a study showing that people who floss have a 37% decrease in the occurance of heart attacks.” My Mother then calls to tell me that they said on the news I can prevent a heart attack by flossing my cartoon3teeth. But that is not what they found. They only found that flossing and lower incidence of heart attacks occur together; they are correlated. I then think to myself that people who floss their teeth care a bit more about taking better care of themself in many ways. I bet they also exercise more, consume more vegetables and are less likely to smoke or binge drink. Does flossing also cause you to eat more broccoli? I’d be more convinced that a person who exercised more also flossed more and that it was exercise that prevented the heart attack. For me, this story got more interesting, however. I have a friend, Adam, who was thinking about going into dentistry. We were having lunch when he described (without knowing my opinion on the matter) a study he was reading that showed how a certain bacteria between one’s teeth was found to be able to enter the bloodstream and grow in the valves of the heart. Ah, ha! Now we are closer to a cause, and while the mechanism of how the bacteria causes the heart to fail are not all laid out, what was a weak inductive argument is now a stronger one. 

Slippery Slope

With a slippery slope argument the facts are distorted by carrying a position to an unrealistic extreme. What had been a moderate position is then carried step by step to a completely irrational one; a position that only a lunatic would approve of. Examples of this occur in a great deal of debates, both formal and on the Sunday talk shows. I will give a few from both sides of the political spectrum. Do not misread my choice of examples for my personal postion on a subject. That fallacy will be covered later.

Example from the gun control argument: If you ban assault weapons (guns that can fire up to 6 rounds/second), the next thing they’ll ban are handguns you can use to protect yourself, then hunting rifles will be illegal, then bb guns, slingshots and eventually our children will be arrested for possession of a squirt gun! We will all soon be at the mercy of Bambi and armed criminals running amok through our subdivisions. With this destruction of the 2nd Amendment, the government will eventually be in possession of all the guns and we’ll see the rise of Big Brother and a Brave New World dystopia. That’s what will happen if you start banning assault weapons!

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Example
from the abortion debate: If partial birth abortions are illegal, soon all abortions will be illegal, and then even for cases of rape, incest and to protect the life of the Mother, next, sex education will be prohibited, followed by the banning of all condoms, and soon venereal disease will be rampant and unwanted children will be commiting crimes everywhere!

Example from the question of gay marriage: If two men or two women are allowed to get married, then soon polygamy will be legal, then people will start marrying their pets and even the pets will be marrying each other. All moral chaos will ensue. Everything imaginable will have State sanction.

The Red Herring and the Strawman

With these two fallacies, the facts are distorted by substituting the issue at hand with another one that seems closely related, but is not in fact, and is also far easier to prove wrong. The name “Red Herring” is derived from the tactic prisoners would use to help them escape by smearing their bodies with fish and then throwing the dogs off their trail. With a “Strawman” argument you give your opponent CartoonU8 Strawman copypositions that they don’t actually hold, positions far more extreme, and then you hope that they will be tricked into trying to defend them.

Red Herring: She may have stolen the dress but how are poor children suppose to be able to attend the Prom?

Red Herring: If we ask the Association to shovel our snow it would be expensive. Can you imagine how much it will cost when we have to have our houses repainted?

Strawman: Anyone who opposes our participating in the war in Afghanistan is against woman having equal rights in this world. The Taliban trampled on any freedom for women. You obviously must not care  about women either.

Strawman: “I like sunny days.” “But if all days were sunny we wouldn’t have any rain and all the crops would wither and die. People would starve.”

Now let’s see how we can misuse the facts by overlooking them. Two fallacies are especially common here.

Black or White (also known as bifurcation)

When a person commits this fallacy they allow no middle ground between their position and the exact opposite one. Things are either black or white. There are no shades of grey. They admit no subtlety in the the issue at hand or the solution to a problem.

Here is one great example from George W. Bush regarding terrorism: “Either you are with us or you are against us.” Or you can press HERE to see for yourself.

[Note: here I do express my personal opinion] After the 9/11 attacks, there was great sympathy for the United States around the world. We could have gotten a lot of help in our effort to rid the world of terrorism. But saying “either you are with us or you are against us” turned out to mean “my way or the highway.” We wasted world sympathy and political capital by disregarding foreign opinion that differed from ours but with the same goal. Without much help (except from the UK) we embarked on two costly wars; one on false premises. Perhaps it would have been a good idea to listen to other opinions in the “grey” zone.

Sweeping Generalization and Hasty Generalization

In the fallacies of sweeping generalization and hasty generalization, the facts are distorted by misapplying the relationship between a generality and a specific example; between a rule and a case. If one applies a cwln1277lgeneral rule to a specific case where it does not apply because of some exceptional quality of the specific case, this is the fallacy of sweeping generalization.

Example of Sweeping Generalization: I wouldn’t mind having a gay son actually. Imagine all the money I’d save on haircuts!

Example of Sweeping Generalization: You should do unto others as you’d like them to do unto you. I often wish I could have help on tough exam questions. Therefore, I should help my classmate who seems to be struggling on this test.

Generalizations, when used properly, can help us to discern universal truths with a reasonable amount of certainty and they hold a proper place in logic. When used improperly, however, they are evidence of mental laziness and can cause great harm. How much easier it is to evaluate a job applicant on the basis of a racial stereotype; much easier than doing the work of discerning the person’s individual merits and shortcomings. Prejudice is simply a case of sweeping generalization.

With hasty generalization, one commits the reverse error of sweeping generalization. Here, a general rule is presumed from too few, or even a single, case.

Example of Hasty Generalization: My husband would accede to my wishes verbally and then do exactly what he wished. He wouldn’t tell me he was annoyed by something I did either – he would leave clues for me to figure that out. All men are passive-aggressive.

Example of Hasty Generalization: The weather in February is horrible! I can see why they made it the shortest month of the year! [They observe the weather in one month and generalize that that is how the length of the month is calculated]

Finally, we may misuse the facts by avoiding them entirely. It may look like we are dealing with relevant facts when we really aren’t.

Begging the Question

This is a strange, yet surprisingly common logical fallacy. When a person “begs the question” they simply

This is what "Begging the Question" Feels like when it's happening.

This is what “Begging the Question” Feels like when it’s happening.

restate their conclusion in different words that are more convoluted and deceptive. The person on the other side of the argument may feel frustrated, like the argument didn’t progress anywhere, yet not know quite precisely what went wrong.

Example: Of course we should have have free trade. The untaxed flow of goods between countries that occur when barriers to commerical transactions are lifted raise the quality of life to all parts of this nation.

Example: God exists because it says so in the Bible. And everything in the Bible is true because it is the word of God.

Humorous example: When Hubert Humphrey, the Democrat, failed to carry Illinois in the 1968 Presidential election, Mayor Daley of Chicago was asked how this could have happened. He replied: “Because he failed to get enough votes.”

Complex Question

The Complex Question fallacy is similar to Begging the Question in that at least parts of the conclusion are a repetition of the premises, only this time it is stated in the form of a question. It is often called by other names such as “Trick Question” or “Loaded Question”. Complex questions need not be a fallacy at all if the premises are true: “Who was the last country to win the World Cup?” Here, there is such a thing as a World Cup and, indeed, it is won by a country. If, however, imagesone of the premises are false, and the person to whom the question is addressed actually answers, they are acceding to this false premise.

Example: How did you clean your fingerprints from the gun? – If one simply says “I didn’t!” it could be taken as an admission that you once held the gun.

Here is a classic example because it shows the fallacy so clearly: “Have you stopped beating your wife?” The respondent had better answer that they never beat their wife in the first place.

Example: Why does does the water level rise when you add a dead fish to it, but not when you add a live fish? If you start to make up theories to explain this question you are doomed. Both a dead fish and a live fish cause the water level to rise. This was a debated question in 18th century Britain until someone actually performed the experiment.

This is the end of my discussion of presumptive informal fallacies where the facts are misused, and this is a reasonable place to end this post before it get’s too long. My next post on critical thinking will discuss fallacies of relevance where at least one of the premises are unrelated to the conclusion, and fallacies of ambiguity where the language is obscure.cman433l.jpg

Posted on January 17, 2013, in Uncategorized and tagged , , , , , , , , , , , , , , , . Bookmark the permalink. 9 Comments.

  1. An early morning lesson in logic… Great way to start the day! I took Logic and Set Theory last semester, it was a math course, not easy at all, but your depiction was a lot more palatable and entertaining. Therefore, I understood it :-)))

  2. I THINK you spend a great deal of time thinking, which is why I think you are so in tune with the world . Did I use the word think too often? I’ll think about it. 🙂
    All kidding aside, astute as always, clearly written and the cartoons are fun. 😉

  3. @Jana – Thank you for reading it Jana! I appreciate it. You took Logic and Set Theory last semester? How did that happen? @Crys, I think you think about how the world thinks. So we better start getting it right!

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