The Most Common Logical Fallacies

atkins-bookshelf-booksBecause of its easy access and the ability to offer anonymity, the Internet has become the defacto setting for debates of an increasingly wide range of topics. Not all debates, however, are created equal; they vary widely and can be fairly judged by the quality of intelligence, expertise, logic, and rhetoric that each participant brings to the discussion. Any experinced reader will recognize that sometimes the discussions in online communities are rational, objective, intelligent and helpful. Sometimes the discussion are spectacularly derailed by internet trolls (the bane of the Internet) that lob their incendiary barbs into a once-civilized forum, setting off an explosive war of words. Other times, well-intentioned — and well-educated — people simply fall into the trap of logical fallacies (common errors in reasoning) that steer the discourse away from being constructive and objective. (Unless you are a politician and logical fallacies are your weapon of choice!)

Enter Ali Almossawi’s marvelous little tome, An Illustrated Book of Bad Arguments — an antidote to the wacky, freewheeling debates (you know the kind: “don’t confuse me with the facts, I’ve already made up my mind”) flourishing in forums, chat rooms, and blogs. Almossawi, a software engineer (degrees from MIT and Carnegie Mellon University) by day and philosopher by night, presents 19 of the most common logical fallacies written in clear, comprehensible language (eschewing the fancy Latin nomenclature); each is paired with an amusing pen-and-ink illustration. In short, the book cuts a safe path through the minefield of reasoning by specifically highlighting the mines to circumnavigate. Almossawi asserts: “[Formalizing] one’s reasoning could lead to useful benefits such as calirty of thought and expression, improved objectivity, and greater confidence… My hope is that the reader will learn from these pages some of the most common pitfalls in arguments and be able to identify and avoid them in practice.” To the end, here are some highlights from this clever book. Go forth and argue passionately and logically…

Attacking a Straw Man or Straw Man Argument
Definition: To intentionally criticize a person’s argument by focusing on a misrepresentation rather than on the actual argument. (Often confused with  ignoratio elenchi, or the Chewbacca defense, that presents an argument that may or may not be logically valid, but does not address the relevant issues.)
Example: “That old fool Darwin believes that humans were once wild chimpanzees swinging from tree to tree.”

Appeal to Irrelevant Authority
Definition: Invoking the assertion by someone who is not an expert on the specific topic to support an argument.
Example: “Professor X, who teaches English at Nameless University, stated that the black holes cannot be seen and thus do not exist.”

Definition: Changing the meaning of a critical word during an argument to support an argument not based on fact.
Example: “How can you object to faith, when you often take leaps of faith yourself — for example, trusting friends, investing in the stock market, choosing a spouse.”

False Dilemma (Black-and-White Thinking)
Definition: An argument that considers only a limited (usuallly two) alternatives, excluding other options.
Example: “Were Chicago to regulate noise from bars that are near neighborhoods, would mean shutting down all the bars.”

Not a Cause for a Cause
Definition: An argument that confuses correlation with causation.
Example: “When I wear my watch, I always run faster and win races.”

Appeal to Fear
Definition: Uses deception or propaganda to create a sense of fear in order to support an idea.
Example: “If you vote for candidate X, the economy will collapse.”

Hasty Generalization
Definition: Reaching a conclusion based on insufficient evidence or a small sample group.
Example: “I spoke to five neighbors and all of them are voting for candidate X, thus the entire neighborhood will vote for candidate X.”

Appeal to Ignorance
Definition: Proposes that an argument is true because there is no evidence to prove that it is false.
Example: “God exists because there is no proof that He doesn’t exist.”

No True Scotsman
Definition: Retaining an initial unreasoned universal assertion by arbitrarily changing the criteria/definition in order to exclude an example that disproves that universal assertion.
Example: “American presidents are completely honest.” [Counter argument: what about Nixon?] “Well, Nixon was not a true American.”

Genetic Fallacy
Definition: An argument is either supported or dismissed based on someone’s or something’s origins.
Example: “He is an American; of course he supports the right to bear arms.”

Guilt by Association
Definition: Discrediting an argument by asserting that it is commonly held by another unpopular group.
Example: “The movement to legalize pot will lead to anarchy because it is held by a bunch of middle-aged, over-the-hill hippies.

Appeal to Hypocrisy
Definition: Discrediting a person’s argument by pointing out that it conflicts with the past actions or statements of that individual.
Example: “Should we listen to the call to reform by an animal rights activist who comes to this debate wearing a leather jacket?”

Appeal to the Bandwagon (Appeal to the Masses)
Definition: An argument is supported because many people believe it.
Example: “UFOs exist because according to a recent poll, a majority of Americans believe in them.”

Slippery Slope
Definition: An argument that without any evidence asserts that some event (or chain of related events) will follow from another event.
Example: “Easy access to violent video games will lead to acts of aggression, then increased homicide rates, and finally complete lawlessness all across the country.”

Ad Hominem
Definition: To discredit an argument by directly attacking the person making the argument.
Example: “How can Candidate X know anything about tax reform when he was convicted for tax evasion ten years ago.”

Circular Reasoning
Definition: An argument that relies on an assumed conclusion in several (generally two) premises, often taking the form: “Because of X then X.”
Example: “God wrote the Bible because it says so in the Bible.”


Read related posts: The O.J. Simpson Trial and the Chewbacca Defense
The Most Common Myths About Shakespeare
Who Designed the Apple Logo?

Top Thanksgiving Myths

For further reading: An Illustrated Book of Bad Arguments: Learn the Lost Art of Making Sense by Ali Almossawi, Workman Publishing (2014)

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