Logical Fallacies

Feb 21, 2025 · 2098 words · 10 minute read

Fallacy Name	Alternative Name(s)	Definition	Examples
Ad Hominem	Personal Attack, Argument Against the Person	Attacking the person making the argument rather than addressing the argument itself.	“You can’t trust Jane’s climate change research because she drives an SUV.” “Don’t listen to Bob’s economic policy - he went bankrupt once!”
Appeal to Authority	Argument from Authority, Argumentum ad Verecundiam	Using the opinion of an authority figure or institution in place of actual evidence.	“Doctor Smith says this supplement works, so it must be effective.” “MIT researchers endorsed this theory, so it must be correct.”
Appeal to Emotion	Argumentum ad Passiones	Manipulating emotions rather than using valid reasoning to persuade.	“Think about the children!” when arguing for internet censorship. “Our soldiers died for this flag, so it’s disrespectful to kneel.”
Appeal to Ignorance	Argumentum ad Ignorantiam	Claiming something is true because it hasn’t been proven false, or vice versa.	“No one has proven ghosts don’t exist, so they must be real.” “Scientists haven’t found the missing link, so evolution must be false.”
Appeal to Nature	Naturalistic Fallacy	Arguing that because something is “natural” it is therefore valid, justified, good, or ideal.	“This medicine is natural, so it’s better than synthetic drugs.” “Humans naturally eat meat, so vegetarianism is wrong.”
Appeal to Novelty	Argumentum ad Novitatem	Assuming something is better because it’s new or more recent.	“This is the newest weight loss technique, so it must be more effective.” “The latest management theory must be better than older approaches.”
Appeal to Popularity	Bandwagon Fallacy, Argumentum ad Populum	Claiming something is true or good because it’s popular.	“Everyone is buying this brand, so it must be the best.” “Millions of people believe in astrology, so there must be some truth to it.”
Appeal to Tradition	Argumentum ad Antiquitatem	Claiming something is right or good because it’s traditional or long-established.	“We’ve always done it this way, so we shouldn’t change.” “Marriage has traditionally been between a man and woman, so it should stay that way.”
Begging the Question	Circular Reasoning, Petitio Principii	An argument where the conclusion is assumed in the premises.	“The Bible is true because it’s the word of God, and we know it’s the word of God because the Bible says so.” “Free will exists because people make choices freely.”
Cherry Picking	Suppressed Evidence, Incomplete Evidence	Selectively choosing data that supports your argument while ignoring contradictory evidence.	“Global warming isn’t real - look at how cold it was this winter!” “The economy is strong - just look at the stock market!” (while ignoring poverty rates)
Composition Fallacy	Fallacy of Composition	Assuming that what is true of parts is true of the whole.	“Each brick is light, so the wall must be light.” “Every player on the team is a star, so they must be the best team.”
Division Fallacy	Fallacy of Division	Assuming that what is true of the whole is true of the parts.	“The university is prestigious, so every student must be exceptional.” “This company is profitable, so each department must be profitable.”
False Cause	Post Hoc Ergo Propter Hoc, Correlation not Causation	Concluding that one event causes another simply because they occurred in sequence.	“I wore my lucky socks and won the game, so the socks caused the win.” “Rates of autism increased along with vaccination rates, so vaccines must cause autism.”
False Dilemma	Black-and-White Thinking, Bifurcation, Either/Or Fallacy	Presenting only two options when more exist.	“Either we cut all environmental regulations, or everyone loses their jobs.” “You’re either with us or against us.”
Fallacy of Relevance	Red Herring	Introducing irrelevant information to divert attention from the real issue.	In a debate about tax policy, bringing up the opponent’s personal life. “We shouldn’t worry about climate change when there are terrorists to fight.”
Genetic Fallacy	Fallacy of Origins	Judging something as good or bad based on where it comes from rather than its current context.	“That idea came from a communist, so it must be dangerous.” “This tradition started in a primitive society, so it’s outdated.”
Hasty Generalization	Jumping to Conclusions, Secundum Quid	Drawing a broad conclusion from too small a sample.	“My neighbor is rude, so people from his country must be rude.” “The first iPhone user I met loved it, so all iPhone users must love them.”
No True Scotsman	Appeal to Purity	Modifying a general claim to exclude counterexamples.	“No true Christian would commit a crime.” When presented with a counterexample: “Well, they weren’t a true Christian then.”
Slippery Slope	Thin Edge of the Wedge	Arguing that a small step will inevitably lead to extreme consequences.	“If we allow same-sex marriage, next people will want to marry their pets!” “If we ban one type of gun, eventually all guns will be banned.”
Straw Man		Misrepresenting someone’s argument to make it easier to attack.	“Vegetarians think everyone who eats meat is evil” instead of addressing their actual environmental or ethical concerns.
Texas Sharpshooter	Clustering Illusion	Cherry-picking data clusters to suit an argument or finding a pattern to fit a presumption.	Drawing a target around bullet holes after they are fired. “Cancer rates are higher in this neighborhood, so it must be the power lines” (ignoring other factors).
Tu Quoque	Appeal to Hypocrisy, Whataboutism	Avoiding criticism by pointing out similar flaws in the critic.	“You criticize me for lying, but you lie too!” “Why focus on our country’s human rights abuses when yours has problems too?”
Middle Ground	Argument to Moderation, False Compromise	Assuming the middle position between two extremes must be correct.	“Some say the Earth is flat, some say it’s round, so it must be somewhat flattened.” “If one person wants to invest nothing and another wants to invest everything, investing half must be right.”
Burden of Proof	Onus Probandi	Shifting the burden of proof to the other side inappropriately.	“Prove to me that invisible unicorns don’t exist.” “You claim my product doesn’t work - prove it!”
Ambiguity	Equivocation	Using a term with multiple meanings in different parts of an argument.	“Theory of evolution is just a theory, and theories are unproven guesses.” (Using “theory” in scientific vs. colloquial sense)
Anecdotal Evidence		Using personal experience or isolated examples instead of valid argument or evidence.	“Smoking can’t be that bad - my grandfather smoked a pack a day and lived to 95.” “I know someone who won the lottery twice, so it must be easy.”
Appeal to Consequences	Argumentum ad Consequentiam	Arguing that a proposition is true or false based on whether the consequences are desirable.	“Free will must exist, otherwise we couldn’t hold people accountable.” “God must exist, otherwise life would have no meaning.”
Appeal to Motives	Appeal to Intention	Evaluating an action based on the actor’s motivation rather than the action itself.	“He meant well, so what he did wasn’t wrong.” “They donate to charity only for tax benefits, so it’s not really generous.”
Appeal to Ridicule	Reductio ad Ridiculum	Presenting the opponent’s argument in a way that makes it appear absurd.	“You believe in evolution? So you think your great-great-grandfather was a monkey?” “You’re against this war? I guess you just want our enemies to win!”
Argument from Silence	Argumentum ex Silentio	Assuming that someone’s silence on a matter suggests agreement or knowledge.	“The company didn’t deny the allegations, so they must be true.” “Historical records don’t mention dinosaurs, so they couldn’t have existed.”
Authority by Proxy	Courtier’s Reply	Dismissing criticism because the critic hasn’t read or studied certain sources that supporters deem essential.	“You can’t criticize this philosophy unless you’ve read these 12 obscure texts.” “Your criticism of this religion is invalid because you haven’t studied theology.”
Blind Loyalty	Tribalism Fallacy	Defending a position simply because it comes from one’s preferred group.	“I’ll vote for any candidate from my political party, regardless of their policies.” “My country could never commit war crimes - that must be propaganda.”
Confusing Correlation with Causation	Cum Hoc Ergo Propter Hoc	Assuming that because two things occur together, one must cause the other.	“Ice cream sales and drowning rates both increase in summer, so ice cream causes drowning.” “Countries with more internet access have higher depression rates, so internet causes depression.”
Continuum Fallacy	Sorites Paradox, Line-Drawing Fallacy	Rejecting a claim because of the inability to define a precise distinction.	“You can’t define exactly when a person becomes ‘old,’ so aging doesn’t exist.” “Since there’s no clear boundary between red and orange, color distinctions are meaningless.”
Etymological Fallacy		Believing a word’s current meaning must match its historical origin.	“Literally means ‘according to the letter,’ so it can’t be used for emphasis.” “Philosophy means ’love of wisdom,’ so philosophers must be wise.”
Fallacy Fallacy	Argument from Fallacy	Assuming that because an argument contains a fallacy, its conclusion must be false.	“Your argument for climate change includes an appeal to authority, therefore climate change isn’t happening.” “You used ad hominem, so your entire position on tax policy is wrong.”
Gish Gallop	Proof by Verbosity	Overwhelming an opponent with numerous arguments, regardless of their accuracy or strength.	In a debate, rapidly listing 20 points that would each take minutes to properly address. Producing a wall of text with many minor points to exhaust the opponent.
Impact Bias	Focusing Effect	Overestimating the length or intensity of future emotional states.	“If I don’t get this job, I’ll be devastated forever.” “Winning the lottery would solve all my problems and make me permanently happy.”
Kettle Logic		Using multiple inconsistent arguments to defend a position.	“I never borrowed your kettle; it was already broken when I borrowed it; I returned it in perfect condition.”
Ludic Fallacy		Assuming theoretical models apply perfectly to real-world situations with their complexities and randomness.	“This investment strategy works perfectly in simulations, so it must work in the actual market.” “Our disaster plan accounts for every variable, so we’re completely prepared.”
McNamara Fallacy	Quantitative Fallacy	Making decisions based solely on quantitative observations while ignoring qualitative factors.	“The school has high test scores, so it must be a good school” (ignoring student wellbeing, creativity, etc.) “The economy is doing well because GDP is up” (ignoring inequality, quality of life, etc.)
Moralistic Fallacy		Arguing that something is the way it should be because that would be better or more moral.	“Humans shouldn’t be naturally violent, therefore they aren’t naturally violent.” “All people should be treated equally under the law, therefore all people are equal in abilities.”
Moving the Goalposts	Raising the Bar	Changing the criteria of proof after the initial criteria have been met.	“If climate change is real, show me the data.” When shown data: “That’s just one study, show me more.” When shown more: “Those are all from biased sources.”
Nirvana Fallacy	Perfect Solution Fallacy	Rejecting a solution because it is not perfect.	“Seatbelts don’t prevent all car accident deaths, so they’re useless.” “This cancer treatment only works 70% of the time, so we shouldn’t use it.”
Poisoning the Well		Presenting unfavorable information about someone before they make their case in order to discredit them.	“Before listening to the scientist’s lecture, you should know he once worked for an oil company.” “Before I introduce our speaker, remember that her family has political connections.”
Prosecutor’s Fallacy		Confusing the probability of finding evidence given innocence with the probability of innocence given evidence.	“There’s only a 1 in 10,000 chance of finding this DNA pattern at random, so there’s only a 1 in 10,000 chance the defendant is innocent.”
Reification	Hypostatization	Treating abstract concepts as if they were concrete things.	“The invisible hand of the market will solve the problem.” “History has shown that freedom always triumphs.”
Survivorship Bias		Focusing on successful examples while ignoring failures that didn’t survive.	“Look at these college dropouts who became billionaires!” (Ignoring millions of dropouts who didn’t succeed) “This old building was built so well - they don’t make them like they used to.” (Ignoring all the old buildings that collapsed)
Special Pleading		Making an exception to a general rule without justifying the exception.	“Everyone needs evidence for their claims - except for my religious beliefs, which are based on faith.” “All politicians are corrupt, except the ones I support.”
Thought-Terminating Cliché		Using a truism or cliché to shut down questioning or critical thinking.	“It is what it is.” “Everything happens for a reason.” “You can’t make an omelet without breaking eggs.”
Sunk Cost Fallacy	Escalation of Commitment	Continuing a behavior or endeavor due to previously invested resources, regardless of the current cost/benefit analysis.	“I’ve already spent $5,000 fixing this old car, so I should keep repairing it.” “We’ve lost 10,000 soldiers in this war already, we can’t withdraw now or those deaths would be in vain.”