What are logical fallacies? Learn about 20 common logical fallacies that are often used to construct an argument. Understanding these faulty arguments can help prepare you to make a better, more logically sound one.
What Are Logical Fallacies?
A logical fallacy is an error in the reasoning behind an argument. Arriving at a point through invalid reasoning creates an invalid argument. It’s important to remember that an invalid reason doesn’t necessarily mean the conclusion is false, but it is important to carefully build a conclusion based on sound reasoning and valid arguments.
These types of logical fallacies occur in formal and informal arguments. Whether you’re writing an academic paper or discussing the latest news with your friends, these logical fallacies examples use faulty reasoning to come to a conclusion.
There are many different types of logical fallacies. These 20 fallacies highlight some of the most common ways that invalid arguments are created, though there are many more fallacies in sound reasoning.
While there are many different types, there are distinct similarities between many of these types of logical fallacies. Most fall under two categories:
- Formal — Fallacious in their logical form
- Informal — Fallacious in their form and content
20 Types of Logical Fallacies and Examples
These 20 fallacies include one or more issues with a logically sound argument. Most arguments start with a proposition, move through a set of premises, and arrive at a conclusion. Issues in any stage can create a logical fallacy.
1. Ad Hominem
This phrase means, “to the person,” and stands for arguments that are directed at the speaker, not the argument. Discrediting the character of the person making a claim doesn’t make a claim valid or invalid.
- Example: “How could I agree with you when you lied about your taxes?”
Some ad hominem fallacies attack a person based not on unrelated errors but on personal traits. Claiming that a viewpoint is wrong because it’s held by someone from another ethnic background, geographical area, or someone with another political view. This form of attack targets the other person and ignores the argument itself.
2. Appeal to Authority
Borrowed from the Latin argumentum ad verecundiam, an appeal to authority logical fallacy claims a view is true because it’s held by an authority figure.
- Example: “My doctor voted for this senator, so that must be the right choice.”
Appeals to authority can be as diverse as the definition of authority. An argument can be invalid even if the person is an authority in the relevant area, like a musician supporting a particular band or style of music.
3. Appeal to Ignorance
This argument makes a claim and says it must be true just because neither speaker knows any evidence against the argument.
- Example: “I’ve never met someone who doesn’t like pop music.”
These arguments make it difficult to show an alternative view, particularly if the view isn’t widely accepted in a particular region, community, or environment. An appeal to ignorance is often framed in a way that, even when new evidence is presented, the person doesn’t counter it with a valid argument.
4. Appeal to Pity
Exploiting someone’s feelings of pity or guilt to make an argument is a logical fallacy. These emotional arguments don’t form a rational idea or claim.
- Example: “If we don’t lower the price of college tuition, then I may not be able to afford a degree.”
Another way that an appeal to pity is commonly framed is as an appeal to the underdog. Just because a person, group, or idea may deserve pity doesn’t mean that the proposed idea is valid and should be supported.
5. Appeal to Popular Opinion
This argument claims that an idea is true because it’s held by many individuals or a select group of important individuals. It’s also known as the common belief fallacy or bandwagon fallacy.
- Example: “The world must be round because that’s what most people think.”
As an argument, this fallacy completely avoids the actual validity of any statement and simply seeks to join the crowd. This doesn’t always lead to a correct or logically sound argument.
6. Causal Fallacy
Causal logical fallacies claim that a single, unproven cause must be the explanation of an effect. It ignores any other possibility or the presence of correlation without causation.
- Example: “There’s no way that global warming is true, just look at the temperature outside.”
Two events must be distinctly related in a causal relationship before any claim like this can be made. A causal fallacy automatically assumes one event caused or will cause another, without taking the steps to prove this link.
7. Circular Argument
Circular arguments require you to accept the conclusion in order to make the argument. This arrangement means that the speaker isn’t actually giving any proof of the argument or conclusion.
- Example: “My theory is true because my academic paper says so.”
An argument can’t be its own proof. To be a valid claim, you must support it with logical proof.
8. False Dilemma
This argument eliminates all possibilities except two specifically chosen by the speaker. It attempts to force the other person into a predetermined argument rather than allow them to explore other conclusions.
- Example: “Either you’re a soldier or you’re opposed to war.”
Rarely are there only two possible conclusions. By automatically ruling out other possibilities, a false dilemma claim sets up an artificial situation where the other speaker feels forced to choose the lesser of two evils.
9. Genetic Fallacy
Genetic fallacies deny the truth of an argument based on its source. It focuses on the person or situation rather than the argument itself.
- Example: “You can’t believe that research because the scientist doesn’t believe in global warming.”
This fallacy is very similar to an ad hominem one but with distinct differences. For example, a genetic fallacy can also discount an argument based on the specific situation or location where it was first proposed.
10. Hasty Generalization
Generalizations occur when a phenomenon is claimed to apply to many different cases without providing logical evidence that it does. It quickly comes to a conclusion and definition of how far-reaching that conclusion is rather than taking time to determine whether one conclusion applies to another situation.
- Example: “None of my neighbors have committed crimes, so there must not be any crime in my city.”
A phenomenon must first be proven to be a general one before it can be applied to different cases. Without taking the time to establish the connection between the two, a hasty generalization isn’t based on rational reasoning.
11. Loaded Question Fallacy
A loaded question phrases a question in such a way that the answer is already supposed. The other person must defend against an accusation couched in a question.
- Example: “When was the last time you committed a crime?”
As the listener, it becomes very difficult to simply deny any possible answer to the loaded question. The other person may have formed their response as a question but it clearly contains an accusation, often without sufficient proof.
12. Post Hoc Fallacy
Similar to the causal fallacy, a post hoc fallacy states a cause and effect relationship that hasn’t been proven. It uses hindsight to claim an argument is true.
- Example: “It never rains when I carry my umbrella. Therefore, my umbrella prevents it from raining.”
This fallacy occurs after the event and looks back to discuss the reasoning behind it. While it may be natural to feel hindsight gives special insight into a situation, even a post hoc argument requires logical reasoning and validity.
13. Red Herring Fallacy
A red herring is an argument that has little or nothing to do with the primary argument in order to distract the other speaker. The argument appears on the surface to have a connection but doesn’t rationally explain or support the conclusion drawn by the arguer.
- Example: “I know you don’t like your food, but there are starving people around the world who do.”
This fallacy is a diversion, just like a loaded question. It doesn’t address the actual issue and points to another argument that only appears to be related on the surface.
14. Slippery Slope Fallacy
This fallacy states that a single step will inevitably lead all the way to the end of a spectrum of events. It often predicts extreme situations as the result of a single step.
- Example: “If we legalize any drug, then all illicit substances will be legal and everyone will become an addict.”
It may be important to consider if a single step leads to another single step. To conclude that a single step leads to the final step, also stated as A is equal to Z, can be an overgeneralization.
15. Strawman Argument
Strawman logical fallacies occur when the speaker provides a counterexample to a similar but less substantial version of the original argument. It intentionally or unintentionally creates a poorly crafted or misrepresented view of an opposing view before soundly refuting it.
- Example: “You think a social safety net is a good idea? So you want to give away all our savings to people who refuse to work and will spend it irresponsibly?”
Avoiding a strawman argument requires you to carefully consider opposing views and state them accurately. It’s very easy to downplay an opposing view in an argument, but oversimplifying another viewpoint doesn’t make yours stronger.
16. Tu Quoque
From the Latin phrase “you also,” tu quoque fallacies occur when a speaker is discredited due to behaviors that don’t align with their arguments. It claims that a person must adhere to their own reasoning for it to be valid.
- Example: “How can you think divorce is harmful to families when you were divorced yourself?”
Also known as an appeal to hypocrisy, this fallacy states that an argument can’t be true if the person who states it doesn’t follow it. Similar to an ad hominem fallacy, it’s the false belief that the arguer affects the validity of an argument.
17. Appeal to Probability
If one outcome is possible, then an appeal to probability states that it’s probable. The difference between the two is blurred.
- Example: “It’s possible for you to become the next president. Therefore you’re probably going to be president.”
A view isn’t true just because it’s theoretically possible. The conclusion needs to be carefully argued and shown to be the most probable or definitively true, rather than one that’s only possible.
18. Existential Fallacy
An existential fallacy, or existential instantiation, claims a category exists and makes an argument using it without proving the category. Some categories are obviously fictional, while others seem to exist but are claimed to be true without providing any proof.
- Example: “There are a lot of bridges around our city and all trolls live under bridges. Therefore, there’s a troll nearby.”
This fallacy relies on a categorical syllogism and two universal premises to lead to a particular conclusion. It states a particular conclusion is true just because of two universal premises, without bothering to prove one or both of the premises are true.
19. Fallacy of the Undistributed Middle
This fallacy skips over a middle term or argument to reach a conclusion. It implies a reasonable argument but creates a false syllogism.
- Example: “All poodles are animals. All dogs are animals. Therefore, all dogs are poodles.”
The argument isn’t valid because it doesn’t put the middle term into the conclusion. This form of argument, a categorical syllogism, needs to distribute the middle term in order to be valid.
20. Non-Sequitur Fallacy
Non-sequitur arguments offer a premise that appears logical but has nothing to do with the conclusion. Even if it’s a valid point, it doesn’t prove or deny the conclusion in question.
- Example: “Beaches have sand. People like sand. I should use sand as flooring in my house.”
This argument follows the basic steps of valid reasoning, so it can seem to be logically sound. Unfortunately, one or both of the premises have nothing to do with the conclusion.