Common Logical Fallacies
A flawed argument is one that falls victim to one or more “logical fallacies,” or mistakes of reasoning. Humans make hundreds of these mistakes on a daily basis, but being aware of them can go a long way towards protecting yourself against faulty reasoning. This is hardly a complete list of logical fallacies, but they are the ones most often seen in political discussions.
Most common fallacies have several names, both official and colloquial, and many of the official names are derived from Latin (which can be off-putting for average people). We’ve tried to restrict the following fallacies to their easiest common name, and we give a relatively simple example for each. For the examples, “Smith” is the one committing the fallacy.
For more information about fallacies, a good place to start is Wikipedia’s list of logical fallacies at http://en.wikipedia.org/wiki/List_of_fallacies
There are several fallacies that are “appeals” to various things. Any argument that tries to use anything outside of pure logic is an appeal, but the following are the most common in politics:
(1) Appeal to Anecdote: citing a personal example as representative of a general principle.
Smith: “My adult daughter finds it difficult to afford her birth control pills, therefore birth control is prohibitively expensive for everyone.”
(2) Appeal to Authority: citing the opinion or argument of someone else who is presumed to be more knowledgeable. (This is often questionable when the person cited is an expert in a field that has nothing to do with the topic at hand.)
Smith: “Nobel Peace Prize-winner Monique Harlow believes that the government has been hiding the truth about alien visitations to Earth, and I can’t disagree with her.”
(3) Appeal to Emotion: provoking an emotional response in order to short-circuit debate.
Smith: “If we don’t pass the crime bill, average Americans will be at the mercy of rapists, burglars, and murderous gangs that strike in the dead of night.” (This is an example of an appeal to fear.)
(4) Appeal to Motive: questioning why somebody holds a particular position instead of arguing against it.
Smith: “My opponent only dislikes my climate change bill because he is in the pocket of Big Oil.”
(5) Appeal to Nature: claiming that something natural is inherently superior to something artificial.
Smith: “Complementary and alternative medicine should have fewer government restrictions than pharmaceutical companies, since it relies on herbs and supplements grown in the ground instead of drugs created in a lab.” (Snake venom is 100% natural, too.)
(6) Appeal to Popularity: citing popular opinion to back up an argument.
Smith: “Polls show that over seventy percent of Americans are opposed to the House’s new environmental legislation, which is why the Senate should vote against it.”
(7) Appeal to Tradition: arguing that something is right because it’s old.
Smith: “Bloodletting was an accepted medicinal practice for hundreds of years, so it should be covered by minimum health insurance standards.”
Argument from Ignorance (Ad Ignorantiam): asserting that something is true because it has not or cannot be proven false.
Smith: “Sprinkling sugar on your lawn keeps away tigers. I’ve been doing this for ten years, and I’ve never seen a tiger – not even once.”
Smith: “No one has objected to Pittsburgh’s new parking policies in the newspaper letters to the editor, so I suppose those policies are very good.”
Causation Fallacy (Post Hoc Ergo Propter Hoc): claiming that A must have caused B since B followed after A.
Smith: “Unemployment went up as soon as the president took office, which means the jobless rate is entirely his fault.”
Circular Argument (Tautology, Begging the Question): when the conclusion of an argument is the same as the premise.
Smith: “This law will hurt the middle class, which is why it won’t be good for Americans of average income.”
Equivocation: deliberately confusing the meaning of a word or phrase being used in multiple contexts.
Smith: “Since America is the land of the free, we all have a right to free beer.”
False Dilemma (Bifurcation, False Dichotomy): falsely assuming that there are only a certain number of possibilities or positions in any given argument.
Smith: “Not supporting my bill is the same as fighting for the status quo.”
Genetic Fallacy: positing that the source of an argument is relevant to the logic of the argument.
Smith: “Isaac Newton was led to his theory of gravity by his interest in the occult, specifically the concept of ‘action at a distance,’ therefore anyone who believes in gravity is a follower of the occult.”
Guilt by Association (Association fallacy): attempting to discredit an argument by highlighting something only tangentially related to it.
Smith: “The Nazis used Darwin’s thoughts on natural selection to justify exterminating the Jews, so clearly there is something wrong with the theory of evolution.”
Smith: “My opponent for the office of District Attorney was close friends with Bob Jones and Dan Brown, both who are now in jail.”
Hasty Generalization (Hasty Induction): forming a general conclusion on the basis of a sample that is far too small, usually just one example.
Smith: “My neighbor is a Democrat who believes that the entire American economy should be centrally planned, therefore all Democrats are socialists.”
Irrelevant Conclusion (Non Sequitur, Ignoratio Elenchi): forming an argument in which the conclusion doesn’t follow from the premise(s).
Smith: “John was a tireless defender of worker’s rights, which is why I am certain his nephew is the perfect choice to head the Department of Labor.”
Nirvana Fallacy: assuming that something can only be good if it has absolutely no downside.
Smith: “If just one child is denied a world-class education as a result of your bill to modernize standardized testing techniques, then we must reject it.”
Personal Attack (Ad Hominem, Mudslinging): attacking the holder of an argument instead of addressing the argument itself.
Smith: “I refuse to accept criticism of my position on welfare reform from a man who was convicted of tax fraud.”
Shifting the Burden: placing the burden of proof outside of the person making an argument.
Smith: “Until my opponent proves otherwise, I say he hates America.”
Slippery Slope: claiming that a small step in a certain direction will necessarily lead to an extreme outcome.
Smith: “Once they institute mandatory background checks for firearms, it’s only a matter of time before they take our guns.”
Special Pleading: making arbitrary (and typically difficult to refute) exceptions to a rule or position.
Smith: “Skeptics will never be able to accept psychic powers because psychic energy is rendered inactive in their presence.”
Straw Man Argument: misrepresenting an opposing viewpoint.
Jones: “I don’t think the government should interfere much with an individual’s right to own a handgun.”
Smith: “So you think everybody should be allowed to own an intercontinental ballistic missile!”
Syllogistic Fallacy: assuming two things are directly related because they are both correlated to something else. This is a pretty complicated fallacy that comes in various forms, but the simplest way to look at it is drawing a false conclusion from two correlations (if X is correlated to Y and Y is correlated to Z, then X must be correlated to Z).
Smith: “Something must be done and my proposal is something. Therefore, my proposal must be done.” (This is a specific syllogistic fallacy known as the “politician’s fallacy.”)
Two Wrongs Make a Right (Tu Quoque): justifying a flawed argument or bad behavior by pointing out the flaws in another.
Smith: “Republicans shouldn’t complain about Democrats overusing the filibuster, since they do the same thing when they’re in the minority.”
Unstated Premise (Audiatur Et Altera Pars, Moving the Goalposts): adding a new premise to an argument after it has been made.
Smith: “I have never raised taxes.”
Jones: “What about that cigarette tax you voted for last year?”
Smith: “I meant that I’ve never proposed my own tax increases.”