20 Most Common Logical Fallacies

What is an argument? What is a bad argument? Train your argumentation skills by studying "bad" logic. In this video, we discuss 20 common argumentation mistakes or logical fallacies.

00:00 Introduction: Spot the Fallacy
02:10 What Is an Argument?
05:10 Twenty Most Common Fallacies

06:50 1 — Ad Hominem
09:59 2 — Appeal to Common Belief
12:20 3 — Appeal to Emotion
14:15 4 — Appeal to Law
16:30 5 — Argument from Offence
17:42 6 — Argument from Trauma
21:31 7 — Begging the Question
23:12 8 — Bulverism
25:00 9 — Cherry Picking
28:59 10 — Chronological Snobbery

30:32 11 — False Dilemma
32:35 12 — Genetic Fallacy
33:40 13 — No True Scotsman
35:19 14 — Non Sequitur
37:15 15 — Poisoning the Well
38:52 16 — Reductio ad Hitlerum
41:42 17 — Slippery Slope
43:41 18 — Strawman Fallacy
45:15 19 — Unfalsifiability
47:18 20 — Whataboutism

50:32 Recapitulation (and a Secret)

Spot the Fallacy is a game, a pedagogical tool I developed to help undergraduates who have little (sometimes no) grounding in logic and argumentation.

At the beginning of each course, I introduce and demonstrate 20 “most common” logical fallacies (such as ad hominem, slippery slope, chronological snobbery, etc). I then tell students that I will be *deliberately* committing one fallacy per lecture. And I challenge them to “catch me”.

Eyes light up. Learning becomes a game. The most rewarding part are the fun discussions we have at the end of each lecture about what students found problematic in my argumentation and whether it amounted to a fallacy or not.

Obviously, the purpose is to help hone transferable critical skills, train intellectual and moral virtues, and foster a posture of learning that avoids the opposite pitfalls of naïve credulity and categorical cynicism. Ironically but predictably, learning about “bad” logic has translated into good essays and even better conversations.

I try to mix it up each year by introducing new fallacies. This keeps fresh even for returning students. This year's two new fallacies are Argument from Trauma and Whataboutism.

Oxford-style Online Tutorials with Dr. Jason Lepojärvi:

[josephfox]

I see myself in a lot of these. Thanks to you I can now really improve myself and have even more fallacies!

[TheKingBeyondEverything]

A video that every one needs to see for both Making good arguements and spotting bad arguments.

[WHTJunior]

I came here on a YouTube recommendation, after watching [31 logical fallacies in 8 minutes] by Jill Bearup. Both are very informative. I see people using these all the time online, mainly in forums and politics, and have probably committed some, myself. Together, these videos should help me spot the fallacies more effectively, and improve my debate/discussion skills.

[jjkthebest]

The thing that sucks is that it's incredibly hard not to cherry pick. We have limited time, so we can only analyse so much evidence.

Also, in my experience, logical fallacies are misidentified almost as often as they're committed. I think you know this, since you point out what isn't a fallacy on multiple occasions, but I feel like it's worth reiterating.

[michaelbaker]

I appreciated the slippery slope fallacy being illustrated with a warning about falling on ice.

[fieryjalapenos]

I’ve also heard 9 called the Texas sharpshooter argument. Using only a portion of a quote or article because that exact part supports your argument but ignoring the rest of the article because it refutes your point.

[goldenflames]

I needed exactly this video today for personal reasons, I am SO GLAD I found it, and I am now a loyal fan of your content and will be watching more to learn. This is so digestible and so well put together, and EXACTLY what I needed, thank you SO MUCH for making it 🙌🙌

[WalkmanYT]

Oh wow! Thank you so much for a solid list and explanation of logical fallacies. Not too long, and not too short

[bnease]

Great presentation. No matter how hard most of us try, we all slip up at times: enter the fallacy. I use your list to evaluate my own work. More than half the time, a logical fallacy finds its way into my speeches and writings.

[tiberiusgracchus]

Good video. I'm sure that Dr. Lepojarvi would say that this is just a brief introduction to thinking about logial fallacies. I really enjoy something like this that stimulates the mind.

One conclusion I draw from the video + my own experience: they often come together in twos or threes. Appeal to emotion is most often in the mix. I think that the ones I encounter most often are cherrypicking and whataboutism.

[dannovak]

Just remember this logic will get you the truth but rhetoric will win the day

[Ivan-tdkb]

Logical fallacies are often used to shutdown legitimate concerns. There’s definitely a bias towards being open to possibilities over being cautious.

[sanremy]

"the bank is not open because it is closed" i love this one.

[houstongordon]

Youtube needs a "just make it louder" option where quality goes pit the window and you can boost the volume UNTIL YOU CAN CLEARLY HEAR IT

[theflyingdutchguy]

ever sinds i have been lesrning about logical fallacies. it has become very clear how common these are. and how often people reach wrong and even bad conclusions. it has taught me how incredibly important and handy it is to learn these

[crozdaicolores]

This is one of the best videos ever. Reminds me a lot of David Tomasi. Thank you, Dr. Lepojärvi.

[arandiasjournal]

Thank you so much! This will definitely come in handy for my paralegal studies🙌

[Spanishman]

This is wonderful. Unfortunately I never learned this in school (hindsight is 20/20). When I finally looked for the information the first few videos were political debates and the examples contained. The sad part is that the videos were only a couple minutes long. It doesn't matter what your views are, it takes more than a couple minutes to explain the concepts

[danicapellvonhumboldt]

Very very informative and thorough work. Sharing this on social media. Love to learn about fallacies...

[TylerTheUke]

Thanks for the lecture! I grew up in Sudbury, but its been ages since Ive been back