Logical Fallacies

What exactly are logical fallacies?

and why we should learn to spot them

Logical fallacies are errors in reasoning that undermine the logic of an argument and represent either illegitimate arguments or simply irrelevant points.

They may be intentional or unintentional, and most of them are not very difficult to spot once you focus your eye on them. That is because they fail the test of whether they actually supply evidence to support the underlying claim.

  • Intentional fallacies occur when you are out of arguments, but still wish to press on with your position, or when you willfully follow a strategy to mislead.
  • Unintentional fallacies occur when your grasp of logic is erratic, your train of thought breaks down and you simply fail to hold the line of your arguments. It may happen because you are distracted, angry or emotional in another way, not very familiar with the topic and the underlying facts.

Failure to identify a logical fallacy may lead you to mistakenly accept an argument as valid, leading to false conclusions and possibly groundless action.

Last, but very important: arguments are won or lost not solely on the basis of logic - rhetoric play a very strong role in this, as rhetoric aims to persuade, regardless of the vector of persuasion. Emotions are a key target of rhetoric. Politics, anyone?

Can we avoid them?

Yes. In fact, this is a core critical thinking skill. The good new is, people can learn to avoid logical fallacies as they observe and analyse other people's reasoning and argumentation!

Also, allowing fewer fallacies in your own reasoning can be a great personal goal for those who want to grow and improve!

<a href="https://www.freepik.com/free-photo/suspicious-strict-serious-looking-attractive-clever-african-american-female-student-check-glasses-smirking-disapproval-frowning-displeased-bad-classmate-behaviour-standing-doubtful-look-disbelief_19429732.htm#query=yellow%20person%20error&position=28&from_view=search&track=ais">Image by benzoix</a> on Freepik
Image by benzoix on Freepik

The two types of fallacies

  • Formal fallacies are arguments that have invalid structure, form, or context errors. They are closely associated with 'broken' logic and often imply a relationship, overlap or dependency where none exists or cannot be proven.
  • Informal fallacies are arguments that have irrelevant or incorrect assumptions. Such fallacies involve bringing irrelevant information into an argument or are based on assumptions that prove to be incorrect upon examination. Informal fallacies often arise due to misuse of language or factual evidence.

Should I really be concerned?

It's a good idea to be aware of the presence of fallacies. Sometimes they form an integral part of a well-intended and harmless argument, but in other cases, they may have more serious consequences:


POSITIVES | Thank your brain for these!


  1. Cognitive biases provide a mechanism for ultra-fast decision-making and can make us very efficient
  2. They prevent cognitive overload and allow us to function in both predictable and unpredictable situations
  3. In unfamiliar situations, biases help us make judgements based on previous experience and similarities
  4. Bias awareness can help understand or predict behaviour and diffuse tensions or conflicts

NEGATIVES | Be aware and stay alert for these!


  1. Quick decisions may be sub-optimal and ill-informed
  2. We may jump to conclusions before considering all the facts
  3. We can treat others unfairly and we can be treated unfairly by others
  4. We may be heavily influenced or outright manipulated by others
  5. Biases can seriously distort communication - the same message may be decoded and interpreted in many different manners
  6. Biases are one of the principal impact vectors of disinformation and can be weaponised by malevolent actors

Related resources

Biases which frequently come into play with disinformation and help it influence our opinions and behaviours:

  • Authority bias
  • Bandwagon effect
  • Bias blind spot
  • Confirmation bias
  • Continued influence effect
  • Curse of knowledge
  • Dunning-Kruger effect
  • False consensus effect
  • Halo effect
  • Identifiable victim effect
  • In-group bias
  • Reactive devaluation
  • Selective perception
  • Semmelweis reflex

Suggested use in training

Biases are a complex concept and depending on factors like time available for a training intervention, group size, level of education and age of participants, you may have to use fairly different teaching methods and activities. What we can guarantee, though, is that this is a remarkably engaging topic and your learners will be thrilled to dive into the world of biases!

To get the fun going, you must absolutely pick a handful of biases from our resources and use them to build awareness and understanding of this thought process. Did you know that there are some 200 biases? A challenge to your learners may be to look for them and to report back to the group those biases that they found most intriguing!