Logical fallacies are errors in reasoning that undermine the quality of an argument.

THREAD: 20 common logical fallacies to learn, identify, and avoid:

Ad Hominem

Latin for "to the person" - an attack of the person rather than the argument.

Instead of addressing the argument and its points and merits, the offender attempts to refute the opposition on the basis of personal characteristics.

All-too-common in politics.
The Texas Sharpshooter

A Texan fires a gun at a barn wall and then paints a target around the closest cluster of bullet holes to create the appearance of accuracy.

Selecting and highlighting evidence that supports the conclusion while ignoring evidence that may refute it.
The Bandwagon Fallacy

An assumption of truth on the basis of the majority of people believing it to be true.

"Everyone believes X, so obviously X is true."

Typically offered without regard for the qualifications or ability of the people in question to validate the claim.
Straw Man

The offender ignores the actual argument and replaces it with a flimsy, distorted, easily-refuted argument (a “straw man”).

By replacing a strong argument with a weak one, the offender can create the illusion of an easy, swift victory.
Red Herring

The kippered herring was a smelly fish used to distract hunting dogs while training them to stay focused on a scent.

"Red herring" is now synonymous with distraction.

The offender distracts from the argument with a seemingly related (but actually unrelated) point.
Hasty Generalization

Jumping to conclusions.

Material, wide-ranging conclusions are made on the basis of an immaterial, narrow body of evidence.

Insufficient evidence has been gathered to justify the claimed conclusions.
Appeal to Authority

The over-reliance on the perspective of an "expert" to support the legitimacy of an argument.

The qualifications of the authority figure in the field of question must be considered.

Their support can be a feature - but not a pillar - of the argument.
No True Scotsman

The "appeal to purity" - the changing of the original argument to evade a counter-argument.

You claim a Scotsman never drinks scotch with soda. Charles says he is a Scotsman and drinks scotch with soda. You exclaim that Charles must not be a true Scotsman!
Sunk Cost Fallacy

Sunk costs are the economic costs already invested in an activity that cannot be recovered.

The fallacy is found in thinking that you should continue on the basis of all that you've put in, with no regard for future costs or likelihood of ultimate success.

The conclusion does not follow logically from the premises.

Presented evidence provides little or no actual support for the argument.

“Charles ate fish for dinner and is well-spoken, so he must be a banker.”
False Dilemma

Presenting only two choices or alternatives when there are many more that exist.

Ignores nuance and lends itself to extreme positions.

Typically reduces the potential for compromise, as the two options are painted as being extremely far apart.
Tu Quoque

Latin for “you too” - attempting to discredit an opponent’s argument by pointing out personal behavior as being inconsistent with their argument.

Targeting the hypocrisy of the opponent.

“Don’t question my integrity, look at all of the bad things you’ve done!”
Slippery Slope

An argument that begins with a benign starting point before using a series of successive steps to get to a more radical, extreme end point.

No single step appears ridiculous on the surface, but the connection of multiple steps into a series is highly-improbable.
Begging the Question

A form of circular reasoning in which the argument is presented in such a way that the conclusion is included in the premise.

“Ghosts are real because I once experienced something that had to be a ghost.”

Easy to identify. The logic collapses on itself.
Loaded Question

Asking a question with a presumption built into the question (pre-loaded!).

Typically intended to be inflammatory in nature.

The individual on the receiving end of the question is forced to respond despite the baseless, irrelevant nature of the presumption.
Post Hoc Ergo Propter Hoc

Argues that since Event B followed Event A, Event B must have been caused by Event A.

Just because B followed A, doesn’t necessarily mean that B was caused by A.

Correlation ≠ Causation.

Comes from the roots “equal” and “voice” - a single word or phrase can say two very different things.

Occurs when the offender uses a word or phrase in an intentionally misleading manner that sounds like it’s saying one thing but is actually saying something else.
Personal Incredulity

You are unable to understand or believe something, therefore you argue that it cannot be true.

Complex topics often require significant upfront work to understand, so an inability to understand cannot be used to argue the illegitimacy of a claim.
Burden of Proof

The inability to provide evidence that a claim is false is used as justification that the claim is true.

The burden of proof lies with the person making the claim to provide supporting evidence.

The lack of refuting evidence is not supporting evidence.
The Fallacy Fallacy

Incorrectly assumes that a claim must be false if a fallacy was used to argue the claim.

Just because someone has poorly argued a claim, does not mean the claim itself is definitively false.
So those are 20 common logical fallacies to learn, identify, and avoid.

I will be turning this thread into a longer-form piece for my newsletter, where I will explore these in greater depth (including examples!).

Subscribe below so you don’t miss it: https://t.co/qMB8i60ney
And if you are a job seeker looking to leverage your improved reasoning and debate skills to advance your career, check out my curated job board, where I share unique roles at high-growth companies in finance and tech.

New roles drop every week! https://t.co/33hwlEqYaW
And follow me @SahilBloom for more writing on decision-making, mental models, business, and finance.

You can find all of my threads (120+!) in the meta-thread below: https://t.co/Q2PggDyCJM

More from Sahil Bloom

More from All

You May Also Like


It was Ved Vyas who edited the eighteen thousand shlokas of Bhagwat. This book destroys all your sins. It has twelve parts which are like kalpvraksh.

In the first skandh, the importance of Vedvyas

and characters of Pandavas are described by the dialogues between Suutji and Shaunakji. Then there is the story of Parikshit.
Next there is a Brahm Narad dialogue describing the avtaar of Bhagwan. Then the characteristics of Puraan are mentioned.

It also discusses the evolution of universe.(
https://t.co/2aK1AZSC79 )

Next is the portrayal of Vidur and his dialogue with Maitreyji. Then there is a mention of Creation of universe by Brahma and the preachings of Sankhya by Kapil Muni.

In the next section we find the portrayal of Sati, Dhruv, Pruthu, and the story of ancient King, Bahirshi.
In the next section we find the character of King Priyavrat and his sons, different types of loks in this universe, and description of Narak. ( https://t.co/gmDTkLktKS )

In the sixth part we find the portrayal of Ajaamil ( https://t.co/LdVSSNspa2 ), Daksh and the birth of Marudgans( https://t.co/tecNidVckj )

In the seventh section we find the story of Prahlad and the description of Varnashram dharma. This section is based on karma vaasna.
The UN just voted to condemn Israel 9 times, and the rest of the world 0.

View the resolutions and voting results here:

The resolution titled "The occupied Syrian Golan," which condemns Israel for "repressive measures" against Syrian citizens in the Golan Heights, was adopted by a vote of 151 - 2 - 14.

Israel and the U.S. voted 'No'

The resolution titled "Israeli practices affecting the human rights of the Palestinian people..." was adopted by a vote of 153 - 6 - 9.

Australia, Canada, Israel, Marshall Islands, Micronesia, and the U.S. voted 'No' https://t.co/1Ntpi7Vqab

The resolution titled "Israeli settlements in the Occupied Palestinian Territory, including East Jerusalem, and the occupied Syrian Golan" was adopted by a vote of 153 – 5 – 10.

Canada, Israel, Marshall Islands, Micronesia, and the U.S. voted 'No'

The resolution titled "Applicability of the Geneva Convention... to the
Occupied Palestinian Territory..." was adopted by a vote of 154 - 5 - 8.

Canada, Israel, Marshall Islands, Micronesia, and the U.S. voted 'No'