A logical fallacy is an error in reasoning that renders an argument invalid. In a broad sense, all logical fallacies are arguments in which a conclusion doesn’t follow logically from what preceded it (a non sequitur).
Logical fallacies rely on an emotional appeal and a lie. Unfortunately, logical fallacies work very well on those susceptible to confirmation bias. They are frequently used in bad journalism and in bad politics. Good politics, and good journalism avoid them like humans avoid the plague.
The fact that someone uses a logical fallacy does not mean they’re wrong about the argument, it just means they have yet to make a valid argument.
Understanding logic fallacies helps one to think straight. You can audit yourself for bad arguments. As well as recognize valid and invalid opposing arguments.
Issues with valid arguments on both sides are more difficult to resolve. For example, the abortion issue has valid arguments on both sides that center around when life starts. Does life start at conception? Before? With a heartbeat? When the brain forms? When the child could live outside the womb? When born? Later? There are valid arguments for all of these positions. When an issue has valid arguments on both sides, they can become very interesting because you have to dive in and explore the degree of validity of each valid argument.
Issues that have only one valid argument an only be argued against with logical fallacies and are easier to resolve.
Top 11 Logical Fallacies
The following list are in order of importance (my opinion). Notice each has the Latin translation. I love Latin, but my excuse for including it also includes the fact that it is common to include it when discussing logic. Why? Many still associate logic with the Latin language. For many centuries, Latin was considered the common language of the educated in the Western world and used to communicate in Western cultures around the world. In a real sense, Latin books and scrolls were the predecessor of the original intent of the internet. That is, for scholars to communicate among themselves around the world.
Who gets credit for first developing logic? Aristotle. Although great thinkers stand on the shoulders of their ancestors, Aristotle is the lucky man who frequently gets credit for first developing logic in the Western world. He called the subject analytics.
As you read a summary of each keep in mind that just because someone uses a logical fallacy does not mean they’re wrong about the argument, it just means they have yet to make a valid argument.
1. Personal Attack – “ad Hominem”
A.k.a. poisoning the well. With this fallacy, you use an insult as an argument. A variation of this fallacy is guilty by association.
“Liberals/Conservatives always say _____.”
“Obama’s preacher Jeremiah Wright said a few things I think were anti-American and bad, therefore Obama is anti-American and bad.”
“Trump is a Nazi.”
All of these are invalid arguments and say nothing. To respond, just point out the insult as a logical fallacy and simply ask if they want to present a valid argument. If mixed with other arguments, point out the name calling and only address the rest of the argument.
2. Appeal to Authority – “argumentum ad verecundiam”
With the appeal to authority fallacy, you use an authority you believe as the argument. The problem is that experts are not always right, therefore you should refer to the authority’s argument. In a world where both good and bad authorities can be right, or wrong, about any conclusion, you need to evaluate the
Good authority example,
“The CDC says vaccines do not cause autism.”
Most of us consider the CDC to be a great authority. The problem is that if one believes vaccines cause autism, they may accept this good authority, but they may not. If they don’t, you’ll have to refer them to the CDC justification for their conclusion.
Bad authority example,
“Alex Jones says the government is making people gay, by what they put in the water.”
It’s tempting to simply throwback an ad hominem attack,
“That person is a complete idiot and you should not listen to them ever!”
However, a better reply might be,
“Can you provide me with the argument or evidence the authority used to come up with their conclusion?”
When confronted with stupid, you have to reply by advancing the conversation if you wish to convert stupid to smart.
3. False Equivalence
A false equivalence is an equivalence made between two subjects based on flawed or false reasoning. This fallacy is committed when one shared trait between two subjects is assumed to show equivalence when it does not exist.
A false equivalence occurs when an anecdotal similarity is pointed out as equal, but are not. To be a false equivalence, the claim of equivalence must break down under scrutiny. This error is usually because of an oversimplification or because it is ignoring additional factors.
The pattern of a false equivalence is:
“X = a + b, and Y = a + c. Since they both contain a, X and Y are equal.”
When reduced to math, you can easily see that a false equivalence is bad math, bad logic. Just because two equations have the same value in them does not mean the two equations are equal. That’s silly and easily disproved. Likewise, just because two arguments have a thing in common does not mean they are equal. That too is silly and easily disproved.
4. Straw Man
With this fallacy, you hold up a position that someone does not hold, and then tear it down. Usually the position is weak or ridiculous and easily knocked down.
A good reply,
“You are attacking a position I do not hold. I am not arguing that _____. My position is _____.”
For example, one might argue that,
“Democrats want open borders which will allow criminals into America.”
The reality is that I nor democrats want open borders so this is an argument Democrats are not making. If we have open borders, then criminals would indeed come in more easily. That is true, but Democrats are not arguing for completely open borders.
A sample reply:
“You are attacking a position I do not hold. I am not arguing that I want open borders, nor am I arguing that I want to allow criminals into America. My position is that I want a lawful immigration policy that is consistent, not racist, and abides by international law including the Geneva convention.”
5. Appeal to Ignorance — “argumentum ad ignorantiam”
With this fallacy, you use the fact that we do not know something to imply something else is either true or false. Ignorance (not knowing) is not evidence. Commonly said as,
“a lack of evidence is not evidence.”
Just because you can’t prove something, does not mean it’s true, nor false.
“Mueller has not released his report yet, therefore Trump did not collude with Russia.”
“We haven’t heard anything conclusive evidence that Trump conspired with Russia, therefore Trump did nothing wrong.”
Example against God’s existence,
“We have no evidence God exists, therefore God does not exist.”
Example for God’s existence,
“We cannot prove God does not exist, therefore God exists.”
6. False Choice
A.k.a. False Dichotomy, Black and White Fallacy, Bifurcation Fallacy. A false choice is when you reduce the choices down to two or sometimes three choices but there are actually more choices available.
7. Slippery Slope
A.k.a. Domino Theory. A slippery slope is when you take a reasonable position, and move it to the extreme. One thing doesn’t necessarily lead to the other.
8. Circular Argument – “petitio principii”
A.k.a. begging the question. A circular argument repeats something assumed to be true in the conclusion. The first thing still needs to be proven. These fallacies are presumptuous.
“God’s miracles prove he exists because I have witnessed his glory all around me.”
9. Hasty Generalization
insufficient evidence, stereotyping, overstatement such as
“all the time”
10. Red Herring
aka ignoratio elenchi, distraction-not on topic
11. Appeal to Hypocrisy
aka Tu Quoque, distraction, doesn’t solve problem, divert blame
Logical fallacies avoid discussing the issue directly usually because the person using the fallacy either does not know a valid argument, or they do not really wish to discuss it. People frequently do not wish to discuss issues they want to believe. Sometimes it’s easier to follow feelings or emotions.
The fact that someone uses a logical fallacy does not mean they’re wrong about the argument, it just means they have yet to make a valid argument. You can respond to logical fallacies by pointing them out and asking for another argument. Or, even better, if you know a valid argument that supports the other side, then point out the logical fallacy and give them the better argument and then discuss why you believe one valid argument over another. In essence, you hold a mini-debate with yourself.
For each issue that interests you, try to understand the valid arguments on both sides. When an issue has valid arguments on both sides, it’s good to know because going into a discussion, you already know where both sides will land and can better watch for logical fallacies.