Twenty Cognitive Biases



19 Bad Arguments

(from the Book of Bad Arguments by Ali Almossawi)

1. Argument from Consequences: Speaking for or against the truth of a statement by appealing to the consequences of accepting or rejecting it.

The problem with it: Just because a proposition leads to some unfavorable result does not mean that it is false. And just because it leads to good consequences doesn't make it true.


2. Straw Man: Misrepresenting, misquoting, misconstruing, and oversimplifying in order to caricature a person’s argument and then attack the caricature rather than the original argument.

The problem with it: Making someone’s argument more absurd makes it easier to attack, but doesn’t address the original argument.


3. Appeal to Irrelevant Authority: An appeal to the feeling that others are more knowledgeable.

The problem with it: 1) Experts do not possess an inherent ability to produce absolute truth. 2) Experts in fields other than that of the issue at hand cannot be relied upon to assert the truth of the matter at hand. 3) Appeals to ancient wisdom are false because nothing is particularly true or not true just because it was believed a long time ago.


4. Equivocation: Changing the meaning of a word during the course of an argument and using different meanings to support one’s assertion.

The problem with it: Shifting the underlying meaning of a word during an argument without acknowledging that change is a form of lying called prevarication.


5. False Dilemma: When someone presents only two choices and asserts that one must conclude with one or the other of those choices.

The problem with it: In many instances, there are actually at least several choices and mixtures of choices.


6. Not a Cause for a Cause: Assuming a cause for an event where one does not exist.

The problem with it: Sometimes things happen at the same time as or right after other things by coincidence.

Example: “God looked down and, and he said we’re not going to let it rain on your speech… The truth is it stopped immediately.” – Donald Trump, 1.20.17, Inauguration Day


7. Appeal to Fear: Playing on the fear of the listener by projecting harm in the future if a proposition is accepted or rejected.

The problem with it: This type of argument does not provide evidence which connects a proposition to a conclusion.

Example: “When Mexico sends its people, they’re not sending their best. They’re sending people that have lots of problems… They’re bringing drugs. They’re bringing crime. They’re bringing rapists.” Donald Trump, 7.8.15, presidential announcement speech


8. Hasty Generalization: Generalizing from a sample that is either too small or special to be representative of the whole.

The problem with it: Small sample sizes are misleading at best and considered false data at worse.


9. Appeal to Ignorance: Assuming a proposition to be true only because there is no evidence to prove that it is not. Alternately, presuming something is false simply because they can’t imagine it could possibly be true.

The problem with it: The burden of proof lies with the person making the claim.


10. No True Scotsman: Arbitrarily redefining the criteria for membership into a category in order to challenge a claim.

The problem with it: Shifting the definition of a group does not address the underlying challenge to the assertion, but rather rewrites the rules of the argument to fit a conclusion.

Original Example: (From Thinking about Thinking by Antony Flew) A Scotsman reads a news story about an Englishman who commits a violent crime. He exclaims “No Scotsman would do such a thing.” The next day he reads of a Scotsman who committed an even worse crime, and exclaims “No true Scotsman would do such a thing.”


11. Genetic Fallacy: Using the history or origin of the argument itself to invalidate the argument.

The problem with it: An argument’s origin, and the origin of the person presenting the argument, have no bearing on the validity of the argument itself.

Example: She cannot offer input on how to run the Department of Education because she has never attended public school.


12. Guilt by Association: Discrediting an argument that is shared by a socially reproachable group.

The problem with it: The fact that two groups share something does not equate them both universally.


13. Affirming the Consequent: Assuming that if the consequent is true, then the antecedent must also be true.

The problem with it: This can be proved wrong with a simple logic form. It does not follow that If A then C,C; hence A.

Example: Some self-proclaimed Muslims commit acts of terrorism. Thus all self-proclaimed Muslims commit acts of terrorism.


14. Appeal to Hypocrisy (tu quoque or “you too”): Countering a charge with a personal attack rather than addressing the issue at hand.

The problem with it: It does not keep the focus on the argument itself.


15. Slippery Slope: Arguing that the acceptance of a proposition would lead to an insurmountably bad series of events.

The problem with it: Supposing worse and worse scenarios built on the previous supposed scenario is not built on any evidence, but rather on the fears of the listener.

Example: Allowing same-sex marriage will lead to marriages between humans and animals, such as a box turtle. (from a speech prepared for Texas Senator John Cornyn, 7.18.04)


16. Appeal to the Bandwagon: Using the fact that a large group of people or a majority believe in something as evidence to assert that it is true.

The problem with it: The number of people who believe something is true does not have any bearing on the veracity of the evidence.


17. Ad Hominem (“To the man”): An attack on a person’s character rather than at the argument. The attack may also be on the alleged intentions or motivations of the person for making the argument.

The problem with it: It is a distraction from the original issue at hand, essentially raising a separate argument altogether.


18. Circular Reasoning: Where one implicitly assumes the conclusion in the premise.

The problem with it: It does not introduce any additional information or evidence to support the argument.


19. Composition and Division: Inferring that the whole must have a particular attribute because its parts have that attribute. Or inferring that a part must have an attribute because the whole to which it belongs has that attribute.

 The problem with it: Using this logic produces false evidence.

Example: This presidential Cabinet’s personal wealth when added together is the richest in history, therefore every member of the Cabinet is rich and good at making money.