Don't Fallacy Your Logic

Don't Fallacy Your Logic

Navigating the information world today has become somewhat of a  daunting task. The internet allowed information to spread like wild fire  and not all of it is what it seems. A lot of lies wrapped up with some  truth, agendas promulgated and even trolls just trying to get an  emotional rise out of their next group of victims. How does one orient  themselves in this sea?

One tool for discerning of  information is that of the logical fallacy. A fallacy is pretty much  faulty reasoning in the construction of an argument, so logical  fallacies are errors in that reasoning that end up invalidating the  entire argument. Fallacies can be committed intentionally to manipulate  or persuade by deception, as well as general carelessness or ignorance  on a given topic.

As we can see with this language-independent fallacy:

1. "James is different from Bob."
2. "Bob is a man."
3. "Therefore, James is different from a man."

We're  making the statement that Bob is different from James. Then somehow  making a logical leap to say that because James is different from Bob,  James can't be a man.

Another example would be:

1. "Basket ball players are tall."
2. "Playing basket ball makes you tall."

This  was probably the first logical fallacy I was introduced to and been  rather simplistic I think it's a good one to see how this can be applied  further. If you can't already tell, we're making a selection bias and  presuming an outcome, when all basket ball players are chosen for their  height.

Fallacies have been around for a long time but  the first systematic study we are aware of begun with Aristotle's work,  De Sophisticis Elenchis (Sophistical Refutations). Very much worth a  read for anyone interested to discover more about logical fallacies.

So, what types of logical fallacies exist?


Probably  the most used logical fallacy and is basically exaggerating,  misrepresenting, or just completely fabricating someone's argument.

Example:  John said we should put more money into health services, Carlos  responded by saying John hates our country so much that he wants to  leave us defenceless by cutting military spending.

False Cause

This  is our basketball example from above. It's when we presumed that a real  or perceived relationship between things means that one causes the  other. This is shown a lot in statistics where correlation doesn't equal  causation. Sometimes these things are entirely coincidental or may be  down to a common cause.

Example:  Imagine for a second, we have a fancy chart. Showing an increase in  global temperatures and a decrease in global pirate activity. We can  easily assume from this that pirates cool the earth and their decline is  the cause of global warming.

Appeal to Emotion

This I saw a lot during our local elections in the UK, consistently repeating the rhetoric "Think of the children".

An  attempt is made to manipulate an emotional response in place of a valid  or compelling argument. Arguments may illicit an emotional response but  the fallacy occurs when emotion is used instead of a logical argument,  or to obscure the fact that there is no compelling rational reason for  the position taken. These are all very effective argumentative tactic's  that are completely dishonest. We are all emotional beings bar  psychopaths so creating an emotional response becomes an easy task.

Example:  Gillian didn't much like eating her vegetables but her mother told her  to think about the poor, starving children in a third world country.

Fallacy Fallacy

A  presumption is made over a claim that has been poorly argued or a  fallacy has been used, so the claim itself must surely be wrong. A claim  may be logically coherent but false or vice versa true but not  logically coherent with poor arguments.

Example:  Discovering Charles' fallacy in his argument of eating healthy food,  just because his nutritionist said he should, Carl said we should eat  Ice-cream and snickers every day for breakfast.

Tu Quoque

A  criticism is responded with criticism taking the heat off the accuser.  Pronounced Too-Kwo-Kwee it literally translates to 'you too' and is a  complete red herring and appeal to hypocrisy. This puts the accuser into  the clear and puts the focus back on the person making the original  criticism.

Example: George  had identified that Charles had committed a logical fallacy, but instead  of addressing the substance of his claim, Charles accused George of  committing a fallacy earlier in the conversation.

Personal Incredulity

When  something requires some previous awareness or knowledge making it  difficult to understand, a person would make out like it's probably not  true. Complex subjects will always require some amount of understanding  before one is able to make an informed judgement about the subject at  hand. The fallacy happens because one just dismisses the subject without  gaining that understanding.

Example:  Bill drew a picture of a chimp and a human to show how evolution may  have progressed for us. Richard suggested we were really stupid to  believe that a monkey turned into a human just through random things  happening over time.


An  appeal is made to popularity or the fact that many people do something  as an attempt to validate a claim. The flaw comes in this argument  because just as many people do one thing, that does not validate the  argument they are making. It would be like the earth making itself flat  just to validate the flat-earth theory.

Example:  Gillian had asked George to explain how so many people could believe in  leprechauns if they're only some silly old superstition. George looked  very perplexedly over his pint and nearly fell from his stool.

These  are just a few of the many, many logical fallacies out there. They are  worth learning and trying to apply to yourself and others. This is some  kind of intellectual kung-fu, the vital art of self-defence during a  debate.

Most fallacies fall under one of these four  categories: Fallacies of Relevance, Component Fallacies, Fallacies of  Ambiguity and Fallacies of Omission.

There is also  Occam's Razor which is another useful tool in logical reasoning formed  from logical fallacies. The original Latin "non sunt multiplicanda entia  praeter necessitatem" basically means "don't multiply the agents in a  theory beyond what's necessary." This means if two competing theories  explain a single phenomenon, and they both generally reach the same  conclusion whilst been equally persuasive and convincing then the  logician should always pick the less complex one.

An  example to help illustrate this would be someone coming home from work  to find their dog has vanished from their garden. Now the dog could very  well have vanished into thin air, been a teleporting dog an all. It's  probably more likely though that the dog just escaped because of the  faulty latch on the gate and isn't some canine superhero.