Learn how to spot hidden flaws in everyday reasoning

Gensler's informal fallacies drill is back: new passages drawn from real arguments, more than one right answer, and a guide beside every question.

Fallacies are flaws in reasoning. They make arguments weak or misleading. Because they often seem sound, anyone can be persuaded by arguments that carry them.

In a world gobbled up by AI, where more people have access to a mobile phone than safely managed sanitation, fallacies are everpresent. Sometimes they are conjured up by someone trying to influence public opinion. Other times, they are unwittingly created. You can find them on your Instagram feed and in political campaigns. Even established newspapers can carry them. They are regurgitated by teammates on a coffee break, or by friends at a football game. Knowing how to identify logical fallacies can sharpen your critical thinking and protect you from bad reasoning.

Today, I’m bringing back one of Gensler’s original logical drills designed to help you spot flaws in reasoning: Informal Fallacies (Set R). They feature some of the classic arguments, along with new ones that echo conversations you might see on comment sections of Reddit or YouTube, on topics ranging from climate science and world history to MrBeast’s lunch kits.

You can try the new drills here or play with an interactive demo below:

New passages and real-life examples of fallacies

Set R features Gensler’s library along with a new set of passages. I tried to fill the gaps left by the original by authoring arguments that commit fallacies that were underrepresented. Every fallacy now has between eight and fourteen passages.

The new passages often mention real-life examples. A Nobel laureate insisting vitamin C cures colds. A board of Secretaries of State vouching for a blood test none of them understood. The coldest week in twenty years, offered as proof that the climate isn’t warming.

They name politicians we see in the news today like Trump, Mamdani and Macron. For people more interested in music, football or wider pop culture, there are passages that reference Taylor Swift, Cristiano Ronaldo and characters from fantasy universes like Game of Thrones.

What else is new?

The original LogiCola would only let you pick one answer. But some of Gensler’s own passages commit more than one fallacy. Now you can select up to 3.

You can check the definition of every fallacy by clicking on the guide button. It opens next to the question, so you can go back and forth without leaving the exercise.

Final Notes

Authoring content for this set was harder than the formal translation drills because of the ambiguity that comes with informal fallacies, as well as the risk of letting my personal leanings and worldview blend in. I made an effort to make the drills feel neutral and I’ll keep reviewing and authoring new passages periodically. If you spot anything that feels off, you can always email me or make a post on GitHub. Ideas for new passages are welcome on our Reddit Community.

Thank you Cristina Ungurean and Vania Tabanelli for reading drafts of this. And Miguel Pinto, André Rodrigues, Mariana Rodrigues and Emanuel Martins for helping test the set.