Blog

Logical Fallacies

Why are logical fallacies important to identify?

I am an intuition-driven person. I enjoy roles where I need to understand other people and their needs, towards improving their experience - typically as a statistics educator but lately as a UX researcher. My ability to deeply empathize with others has guided me well. But as I move into roles with more responsibility, it's important to have a more objective framework to complement my intuition.

A logical fallacy is an error in reasoning caused by incorrect logic, making the associated argument invalid. There are many types of logical fallacy. This article is intended to serve as a personal reference list of fallacies, to be updated as I encounter more out in the world 😅.

Ad Hominem

Attacking the person and not their arguments

Red Herring

Bringing up something irrelevant and distracting to the main argument

False equivalences and non-sequiturs are closely related to red herrings as well.

No true Scotsman

aka Appeal to Purity

Protection of a universal generalization from counterexamples by ad hoc changes to the definition to exclude the counterexample

Not always a fallacy; depends on the syntactical context of the term "true"

Begging the Question

aka Begging the Claim

a form of Circular Reasoning

Putting forth a premise that must be true for the claim to be true,

Putting forth a premise that already assumes the conclusion is true.

Restating a point instead of proving it.

Moral Equivalence

Making unfair and/or inaccurate comparisons

Ad Populum

Assuming that because the majority believes it, it must be true

Related to bandwagoning, this fallacy occurs when one assumes that because something is popular then its valid. However popularity alone doesn't validate an agument, although it's often used in marketing! Such arguments don't take into account whether this 'majority' is qualified or whether contrary evidence exists.

Genetic Fallacy

Judging something based on its origins

Texas Sharpshooter Fallacy

Cherrypicking data to make an argument

The fallacy occurs when a discussant doesn't consider the full spectrum of evidence, but instead picks specific patterns/correlations that suit their argument. Evidence that contradicts their argument is ignored or deemed statistically insignificant.

This fallacy gets its colorful name from an anecdote about a Texan who fires his gun at a barn wall, and then proceeds to paint a target around the closest cluster of bullet holes. He then points at the bullet-riddled target as evidence of his expert marksmanship.

Post hoc ergo propter hoc

aka False Cause

Just because B followed A does not mean A caused B

Correlation is not causation!

Either/Or

aka False Dilemma

Making the oversimplifying assumption that there are only two mutually exclusive outcomes, when there are more

Rather than presenting a situation as a spectrum of possibilities, this fallacy presents a complex situation as one of only two outcomes. It misses out on opportunities to compromise or re-frame the issue in a new way.

Appeal to Ignorance

Assuming a conclusion is true because it cannot be disproved

Burden of Proof

Burden lies not with the person making the claim, but someone else

When someone makes a claim, it is up to them to prove it - not to someone else to disprove it.

Special Pleading

Asking for special treatment based on what are believed to be special circumstances

Involves the misrepresentation of the other discussant's argument, typically to make it easier to attach

Straw Man

Oversimplifying/misrepresenting the discussant's argument, to make it easier to attack

Slippery Slope

Assuming the first event A will lead to an extreme result Z

If A happens, then extreme result ZZ will happen, so A should not happen

Hasty Generalization

Generalizing from insufficient evidence

Appeal to Authority

Using the opinion of an authority figure or institution instead of an argument

Loaded Question

Asking a question with a built-in assumption, so that it can't be answered without appearing guilty

Tu quoque

Avoiding engagement with criticism by turning it back on the accuser

Appeal to Nature

Because something is 'natural' it is therefore valid, justified, inevitable, or ideal

Middle Ground

Saying that a compromise between two extremes is the truth

This fallacy is misleading because the extremes could be both true or both false, meaning that the compromise is not valid.

Personal incredulity

Because someone finds something difficult to understand, it's not true

Fallacy Fallacy

Presuming that because a claim has been poorly argued, or a fallacy has been made, that it's necessarily wrong

References

• Quizzma
• 15 Common Logical Fallacies and How to Spot Them