Logical Fallacies

Lie

An outright untruth repeated knowingly as a fact. "I did not have sexual relations with that woman."

Sweeping Generalisation

Applying a general rule too broadly. "Those young men rioted because they lacked morally responsible fathers."

Appeal to Consequences of a Belief

Arguing a belief is false because it implies something you'd rather not believe. "That can't be the Senator on that sextape. If it were, he'd be lying about not knowing her. And he's not the kind of man who would lie."

Appeal to Fear

Argument is made by increasing fear and prejudice towards the opposite. "Before you know it there will be more mosques than churches."

Slippery Slope

Assuming a relatively small first step will inevitably lead to a chain of related (negative) events. "If we legalize marijuana, more people will start using crack and heroin. Then we'd have to legalize those too."

Spotlight

Assuming an observation from a small sample size applies to an entire group. "This large shoe manufacturer employs children in sweatships. Therefore all shoe companies are evil child-slave owners!"

Appeal to Probability

Assuming because something could happen, it will inevitably happen. "There are billions of galaxies with billions of stars in the universe. So there must be another planet with intelligent life on it."

Middle Ground

Assuming because two opposing arguments have merit, the answer must lie somewhere between them. "I rear ended your car, but I don't think I should pay for the damage. You think I should pay for all the damage. A fair compromise would be to split the bill in half."

Undistributed Middle

Assuming because two things share a property, that makes them the same thing. "A theory can mean an unproven idea. Scientists use the term evolutionary theory. Therefore evolution is an unproven idea."

Design Fallacy

Assuming that because something is nicely designed or beautifully visualized it's more true. "Er..."

Division

Assuming that characteristics or beliefs of a group automatically apply to any individual member. "Many Conservatives wish to ban gay marriage, discredit climate change, and deny evolution. Therefore, all conservatives are homophobic, anti-environmental and creationists."

Composition

Assuming that characteristics or beliefs of some or all of a group applies to the entire group. "Recent terrorist attacks have been carried out by radical Islamic groups. Therefore all terrorists are Muslims."

Two Wrongs Make a Right

Assuming that if one wrong is committed, another wrong will cancel it out. "Sure-the conditions in this prison are cruel and dehumanizing. But these inmates are criminals!"

Perfectionist Fallacy

Assuming that the only option on the table is perfect success, then rejecting anything that will not work perfectly. "What's the point of this anti-drunk driving campaign? People are still going to drink and drive no matter what."

Gambler's Fallacy

Assuming the history of outcomes will affect future outcomes, "I've flipped this coin 10 times in a row and it's been heads. Therefore the next coin flip is more likely to come up as tails."

Affirming the Consequent

Assuming there's only one explanation for the observation you're making. "Marriage often results in the birth of children. So that's the reason why it exists."

Genetic Fallacy

Attacking the cause or origin of a claim rather than its substance. "Of course, mainstream liberal media aren't going to say Barack Obama is a Muslim."

Appeal to Pity

Attempt to induce pity to sway opponents. "The former dictator is an old, dying man. It's wrong to make him stand trial for these alleged offenses."

Appeal to Incredulity

Because a claim sounds unbelievable, it must not be true. "The eye is an incredibly complex biomechanical machine with thousands of interlocking parts. How could that exist without an intelligent designer?"

Ad Hominem

Bypassing the argument by launching an irrelevant attack on the person not their claim. "Anyone that says we should build the Ground Zero Mosque is an American-hating liberal."

Confirmation Bias

Cherry-picking evidence that supports your side while ignoring contradicting evidence. "It's obvious 9-11 was an American governement led conspiracy to justify war in Iraq and Afghanistan. No plane hit the Pentagon. The Twin Towers collapse was a controlled demolition, etc."

Ignoring a Common Cause

Claiming one event must have cause the other when a third (unlooked for) event is probably the cause. "We had the 60s sexual revolution, and now people are dying of AIDS."

Appeal to Authority

Claiming something is true because an unqualified or untrustworthy 'expert' says it is. "Over 400 prominent scientists and engineers dispute global warming."

Appeal to Tradtion

Claiming something is true because it's 'always' been that way. "Marriage is the union between man and woman. Therefore gay marriage is wrong."

Appeal to Common Practice

Claiming something is true because it's commonly practiced. "This bank has some problems with corruption. But there's nothing going on here that doesn't go on in all the other banks."

Appeal to Popular Belief

Claiming something is true because the majority of people believe it. "Milk is good for your bones."

Post Hoc Ergo Propter Hoc

Claiming that because one event followed another, it was also caused by it. "Since the election of the President more people than ever are unemployed. Therefore the President has damaged the economy."

Cum Hoc Ergo Propter Hoc

Claiming two events that occur together must have a cause-and-effect relationship. (Correlation = cause) "Teenagers in gangs listen to rap music with violent themes. Rap music inspires violence in teenagers."

Straw Man

Creating a distorted or simplified caricature of your opponent's argument, and then arguing against that. "You say Israel should stop building settlements on the West Bank in violation of treaty. So you're saying Israel doesn't have the right to be a nation?"

Misleading Vividness

Describing an occurence in vivid detail, even if it is rare occurence, to convince someone that it is a problem. "After a court decision to legalise gay marriage, school libraries were required to stock same-sex literature; primary schoolchildren were given homosexual fairy stories and even manuals of explicit homosexual advocacy."

Anecdotal Evidence

Discounting evidence arrived at by systematic search or testing in a favor of a few firsthand stories. "I'm going to carry on smoking. My grandfather smoked 40 a day and he lived until he was 90!"

Guilt by Association

Discrediting an idea or claim by associating it with an indesirable person or group. "Oh you want to relax the anti-terrorism laws just like the terrorists want us to do. Are you saying you support terrorism?"

Appeal to Spite

Dismissing a claim by appealing to personal bias against the claimant. "Don't you just hate how those rich Liberal Hollywood actors go on TV to promote thier agendas?"

Hasty Generalization

Drawing a general conclusion from a tiny sample. "I just got cut off by the woman driver in front. Women can't drive."

Jumping to Conclusions

Drawing a quick conclusion without fairly considering relevant (and easily available) evidence. "She wants birth control in her medical coverage? What a slut!"

Biased Generalizing

Generalizing from an unrepresentative sample to increase the strength of your argument. "Our website poll found that 90% of internet users oppose online piracy laws."

Burden of Proof

I don't need to prove my claim - you must prove it is false. "I maintain long-term solar cycles are the cause of global warming. Show me I'm wrong."

Suppressed Evidence

Intentionally failing to use significant and relevant information which counts against one's own conclusion. "The Iraqi regime possesses and produces chemical and biological weapons. It is seeking nuclear weapons."

Red Herring

Introducing irrelevant material to the argument to distract and lead towards a different conclusion. "The Senator needn't account for irregularities in his expenses. After all, there are other senators who have done far worse things."

Begging the Question

Making a claim while leaving out one or more major contributing factors that may affect the conclusion. "If we label food with warning labels, it will encourage people to eat more healthily."

Appeal to Nature

Making your claim seem more true by drawing a comparison with the "good" natural world. "Of course homosexuality is unnatural. You don't see same-sex animals copulating."

Unfalsifiability

Offering a claim that cannot be proven false, because there is no way to check if it is false or not. "He lied because he's possessed by demons."

Appeal to Ridicule

Presenting the opponent's argument in a way that makes it appear absurd. "Faith in God is like believing in Santa Claus and the Tooth Fairy."

False Dilemma

Presenting two opposing options as the only two options while hiding alternatives. "We're going to have to cut the education budget or go deeper into debt. We can't afford to go deeper into debt. So we'll have to cut the education budget."

Relativist Fallacy

Rejecting a claim because of a belief that truth is relative to a person or group. "That's perhaps true for you. But it's not true for me."

Circumstance Ad Hominem

Stating a claim isn't credible only because of the advocate's interests in their claim. "A study into the health risks of mobile phone involved mobile phone companies. Therefore, the study cannot be trusted."

Appeal to Wishful Thinking

Suggesting a claim is true or false just because you strongly hope it is. "The President wouldn't lie. He's our leader and a good American."

Appeal to Novelty

Supposing something is better because it is new or newer. "Awesome! The latest version of this operating system is going to make my computer faster and better..."

Appeal to Money

Supposing that, if someone is rich or something is expensive, then it affects the truth of the claim. "If it costs more, it must be better."

Appeal to Ignorance

A claim is true simply because it has not been proven false (or false because it has not been proven true). "Nobody has proved to me there is a God. So there is no God."

Circular Logic

A conclusion is derived from a premise based on the conclusion. "Stripping privacy rights only matters to those with something to hide. You must have something to hide if you oppose privacy protection."

Denying the Antecedent

There isn't only one explanation for an outcome. So it's false to assume the cause based on the effect. "If you get a degree, you'll get a good job. If you don't get a degree, you won't get a good job."

Ad Hoc Rescue

Trying to save a cherished belief by repeatedly revising the argument to explain away problems. "...But apart from better sanitation, medecine, education, irrigation, public health, roads, a freshwater system and public order... what have the Romans done for us?"

Appeal to Flattery

Using an irrelevant compliment to slip an unfounded claim which is accepted along with the compliment. "Intelligent and sophisticated readers will of course recognise a fallacy like this when they read one."

Appeal to Anonymous Authority

Using evidence from an unnamed 'expert' or 'study' or generalized group to claim something is true. "They say that it takes 7 years to digest chewing gum."