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What Is a Logical Fallacy?
A logical fallacy is an error in the reasoning process, not in the veracity of the premises. Therefore, logical fallacies are not factual errors, nor are logical fallacies opinions. They are attempts to bypass the steps of a logical argument for the purpose of winning it.
What Is a Logical Argument?
Before one can understand how a logical fallacy is used, one must understand what a logical argument looks like. Generally, an argument has two parts:
- a premise (or premises)
- and a conclusion.
A conclusion is a claim being made, and the premises are the support for that conclusion.
The Two Types of Logical Reasoning
There are two major types of logical reasoning: deductive and inductive.
- Deductive reasoning is such that, if the premises are true, the conclusion must be true. It also moves from general cases to specific ones. Deductive Argument: If an eight-sided figure is called an octagon, and I just drew a figure with eight sides, then I just drew an octagon.
- Inductive reasoning is such that if the premises are true, then they provide some degree of support for the conclusion; the more support, the better (or stronger) the argument. Induction goes from specific cases to generalizations. Inductive Argument: All swans we have seen have been white, therefore all swans are white.
The following is a list of 15 commonly used fallacious arguments, with examples.
1. Slippery Slope
This logical fallacy ignores the basis of either position and argues only that perceived outcomes will occur based on the opposing position, and that those outcomes are undesirable or unattainable.
Examples of the Slippery Slope Fallacy
- "Once all gun owners have registered their firearms, the government will know exactly from whom to confiscate them."
- "If we legalize marijuana, next thing you know we're legalizing crack!"
2. Straw Man
This fallacy involves arguing against a distorted, exaggerated, or otherwise misrepresented version of the original argument. Once this "straw man" of an argument is "knocked down," one claims the original argument has been refuted.
This technique is extremely popular in religious and political circles, where one argues against a distorted and unpopular version of the opposition instead of defending the position held.
Examples of the Straw Man Fallacy
- Person A: I support the separation of church and state.
Person B: So you support godless atheist communism? See how well that worked out in Russia, China, and Cuba?
- "The America I know and love is not one in which my parents or my baby with Down Syndrome will have to stand in front of Obama’s “death panel” so his bureaucrats can decide, based on a subjective judgment of their “level of productivity in society,” whether they are worthy of health care." - Sarah Palin, via Facebook, August 7, 2009, regarding Section 1233 of America's Affordable Health Choices Act of 2009 (Advance Care Planning Consultation)
3. Hasty Generalization
This is a tricky one to spot sometimes because it relies on statistics or examples from a non-representative sample to generalize to the entire population. The example below from the Nizcor Project has two hasty generalizations.
Example of a Hasty Generalization
Bill: "You know, those feminists all hate men."
Bill: "Yeah. I was in my philosophy class the other day and that Rachel chick gave a presentation."
Joe: "Which Rachel?"
Bill: "You know her. She's the one that runs that feminist group over at the Women's Center. She said that men are all sexist pigs. I asked her why she believed this and she said that her last few boyfriends were real sexist pigs. "
Joe: "That doesn't sound like a good reason to believe that all of us are pigs."
Bill: "That was what I said."
Joe: "What did she say?"
Bill: "She said that she had seen enough of men to know we are all pigs. She obviously hates all men."
Joe: "So you think all feminists are like her?"
Bill: "Sure. They all hate men."
4. Ad Hominem
Literally meaning "against man," this argument bypasses the content of the argument entirely and instead focusses on the arguer themselves.
Example of the Ad Hominem Logical Fallacy
Person A: I believe that the Ground Zero Mosque should be allowed to be built.
Person B: You would say that because you are an America-hating liberal.
5. Argument From Authority
This is only a fallacy if the person does not have the authority that they need to make the claim that they are making. Common criteria for identifying someone as authoritative are:
- The person has sufficient expertise in the matter in question;
- The claim being made is within their area of expertise;
- There is an adequate degree of agreement between other authorities;
- The authority is not significantly biased;
- The area of expertise is a legitimate discipline; and
- The authority must be identified.
I will show examples of violations of many of the criteria below. Note that the fact of the matter may be true (as in number 3 below), but the argument is still logically fallacious.
Examples of Arguments From Authority
- The cryptozoologist identified the piece of meat as having been eaten by a Chupacabra.
- I'm glad my psychic gave me my lucky numbers yesterday! I won $20.00!
- Most doctors agree that people take too many antibiotics.
6. Appeal to Majority (Ad Populum)
The appeal to the majority is simply saying that since most people think or believe a certain way, that that way must be correct. Logically, it is a form of a red herring, in that it is irrelevant how many people believe a certain position. Truth exists outside of popular consent. Many people are susceptible to this type of fallacy because they want to fit in.
Examples of Ad Populum
- The Ford F-150 is the best-selling truck in America, therefore it is the best truck.
- More people prefer the taste of Pepsi to Coca-cola, therefore Pepsi is better than Coke.
7. Appeal to Ignorance
This is the fallacy that a statement or belief is false simply because it has not been proven true, or, conversely, true because it has not been proven false. This is a variation of "innocent until proven guilty" that resonates so well in America because it is what our criminal justice system is based upon. However, in logic, neither side has the disproportionate burden of proof; both sides must prove their own conclusions.
Examples of Appealing to Ignorance
- Since no evidence has been collected from UFOs, then they must not exist.
- Scientists don't know exactly what happened in the Big Bang, so it must not be true.
8. Personal Incredulity
This states that simply because someone finds a conclusion unbelievable, that it can not possibly be believable. In this scenario, there is not even an attempt at a logical rebuttal. It is simply stating that the position counter to the one you hold is false because you believe it to be so.
Example of Personal Incredulity
Of course I don't think teaching sex education in first grade is a good idea! No reasonable person could possibly believe that!
9. Ad Hoc
Ad Hoc (meaning "for this purpose") is usually added into an argument to shore up some sort of shaky premise. Technically, this is not a true logical fallacy, in that it is not an error in reasoning, per se, but an explanation.
Example of an Ad Hoc Fallacy
Yolanda: If you take four of these tablets of vitamin C every day, you will never get a cold.
Juanita: I tried that last year for several months, and still got a cold.
Yolanda: Well, I’ll bet you bought some bad tablets.
In a technical sense, all logical fallacies are variations of non sequitur, Latin for "does not follow." This is because their conclusions do not logically follow their premises.
Examples of Non-Sequitur Arguments
- Thousands of Americans have seen lights in the night sky that they could not identify. This proves the existence of life on other planets!
- Joe lives in a big building, so his apartment must be huge.
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Tautology is only a fallacy inasmuch as it is presumed to be furthering the argument. Tautology is simply stating an equivalent, such as A=A. However, often this turns into circular reasoning, saying that the conclusion is true because the premise (which is really the same thing) is true.
Example of a Tautology
The Bible says that it is inerrant, and everything in the bible is true. Therefore the bible is inerrant.
12. Genetic Fallacy
This occurs when there is a perceived defect in the originator of the claim, which means that the claim itself must be false. This is similar to an ad hominem argument except that this can be extrapolated to other things besides people.
Examples of a Genetic Fallacy
- He says that his internet is slow, but he is using a PC and not a mac, so that must be the real problem.
- Of course you don't hear that Barack Obama is a Muslim, you listen to the lamestream liberal media.
13. False Dichotomy
Also known as a false dilemma, a false dichotomy is when two mutually exclusive options are set up as the only two options. When one is refuted, the other option is clearly the only "logical" choice. The fallacy in this situation occurs when both of the options could be false, or that there are other unexplored options. When there really is a true dichotomy (the options presented are in fact the only two options), then this is not fallacious.
Example of a False Dichotomy
Person A: Illinois is going to have to cut spending on education this year.
Person B: Why?
Person A: Well, it's either cut education spending or borrow money and go deeper into debt, and we can't afford to go any deeper into debt.
14. Begging the Question (Unstated Major Premise)
This occurs when there are one or more major premises that are not laid out before the conclusion is made. If both parties agree with those premises, then this may not lead to a problem, but it is still technically a fallacy. As with other fallacies, the assertions made on unstated premises may be true, but the argument can be fallacious nonetheless.
Example of Begging the Question
If we label foods with their cholesterol content, Americans will make healthier food choices.
- cholesterol in food causes cholesterol in people
- better food labeling will reduce Americans' cholesterol intake
- having high cholesterol is a bad thing
- people make food buying decisions based on food labels
15. Correlation Implies Causation
This is a common fallacy where an arguer assumes that two variables are related and causative. The two variables may or may not be related to one another, or they may both be related to something else. This fallacy includes ignoring a common cause, confusing cause and effect, and post hoc fallacies. Ignoring a common cause is when two variables may be related to each other, but caused by a third variable. Confusing cause and effect are when two completely unrelated variables are linked causally. A post hoc fallacy assumes that simply because B occurred after A, that A caused B to happen.
Examples of Correlation Implying Causation
- Confusing Cause and Effect: Atmospheric CO2 levels and drug use have both increased steadily since the 1960s. Therefore carbon dioxide causes people to use drugs.
- Ignoring a Common Cause (Hot Weather): When people buy more water at the ballpark, they also buy more ice cream. Ice cream must make people thirsty.
- Correlating a Single Individual With Multiple Disparate Outcomes: "When Pat Quinn became governor, we had high hopes. What has he done? 215,000 jobs lost, businesses shut down, family homes lost." -Bill Brady for Governor radio ad (post hoc)
- Correlation of Unrelated Events: "We took the Bible and prayer out of public schools, and now we're having weekly shootings practically. We had the 60s sexual revolution, and now people are dying of AIDS." -Christine O'Donnell, Former Republican Senate candidate (Delaware), during a 1998 appearance on Bill Maher's 'Politically Incorrect'"
- Determining God Willed Smallpox for the Desires of Colonizers: "For the natives, they are near all dead of the smallpox, so as the Lord hath cleared our title to what we possess." -John Winthrop, Governor, Massachusetts Colony, 1634
BillyB on July 28, 2019:
Here's one. Just because a statement meets one of the fallacies, doesn't mean that it's not true. Am I right?
Charles Buckwheat on May 19, 2019:
Jason on January 09, 2019:
Good article, but why do all the examples attack Republicans and Conservatives?
pete on April 30, 2015:
I feel that your logic is faulty. Didn't you use a hasty generalization, as well as an ad hominem statement to justify why you used conservative examples.
Also I didn't quite follow your first example on slippery slope. The reason we register cars is so police officers knows who the car belongs to when we get a ticket. So registering a gun wouldn't that be logical to assume that then officers would know who the gun belonged to ? I could be wrong but posing the question isn't unreasonable in my opinion
Jacqui from New Zealand on September 13, 2014:
Ah...I'm seeing a few of these in play here on HP. Thanks for this, very informative!
Aaron Seitler from Manchester, United Kingdom on June 13, 2013:
Wow...if logical fallacy falls under all these categories,what counts as a rational argument?
dosters (author) from Chicago on March 25, 2012:
I know that a lot of my examples do use Republicans and conservatives. The fact that if pushed I would label myself slightly conservative, Christian, and (generally) vote Republican aside, the reason there are so many examples used in this piece is, quite frankly, they generally use them a whole lot more often than "liberal" humanists.
Ryan on March 12, 2012:
For someone who makes the pretense of being rational and therefore not driven by such things as fallacy or bias, I notice that in all of your examples which deal with political or religious situations you attack Republicans and conservatives.
Trust me buddy, you're not that smart as to put one over on me. Maybe when I'm asleep.
megan Grim on February 02, 2011:
wow this helps me a lot to know what is what
Website Examiner on September 25, 2010:
Hello Dosters, this hub is a quality piece of work and demonstrates that you are a capable writer and thinker. Feel free to delete my previous comment, if you wish! W.E.