Appeal to Ignorance

Appeal_to_Ignorance_LargeAppeal to Ignorance is an argument that asserts that something is true because it hasn’t been proven false, or something is false because it hasn’t been proven to be true.

This reasoning is problematic because it ignores the possibility that the truth or falsity of something might just not be known yet. Or that something may be incredibly difficult or impossible to know. This argument shifts the burden of proof to the opposite position instead of providing evidence to support their own position.


“The existence of life on other planets has never been proven, therefore it is reasonable to conclude that such life does not exist.”

“UFOs must be aliens, because there are so many cases where scientists dont’ know what happened and can’t prove otherwise.”


Appeal to Antiquity

Appeal_to_Antiquity_LargeAppeal to Antiquity is the line of thinking that an idea old being old, means that it is better. The fact that something has been done for a long time is treated as evidence. This argument is usually fueled by stubbornness, and a lack of historical context. It avoids evaluating a topic for it’s actual merits or disadvantages.


Ayurvedic medicine has been used for thousands of years, therefore it must have some medicinal value.



Appeal to Emotion

Appeal_to_Emotion_LargeAn Appeal to Emotion is when someone uses emotional consequences or personal feelings to persuade someone of something.

Just because something feels correct, incorrect, negative,  positive, or invokes “feels” of any kind, does not mean that something is better, correct, wrong, etc. Emotional consequences can obscure facts and lead to irrational conclusions. Politicians use this tactic regularly in debates when giving examples of individuals affected by their or their opponents policies.


In 1971 the organization Keep America Beautiful aired an ad depicting a Native American rowing, riding, and walking among an increasingly filthy urban landscape. From a freeway, a passerby throws some garbage at his feet when then he begins to cry. The ad appeals the audience’s notion of a forgotten and ideal landscape, punctuated by the image of a noble savage heartbroken as his former home is transformed into a modern filthy city. Not only does this ad say nothing specific about the environmental impact of littering, except that it makes Native Americans cry, the ad has been accused of being  a politically motivated diversionary tactic, designed to put the burden of waste disposal on the consumer instead of on the manufacturers(see references below).

Heather Rogers(2006). “Gone Tomorrow: The Hidden Life of Garbage ” (http://www.amazon.com/Gone-Tomorrow-Hidden-Life-Garbage/dp/1595581200)

Ariane Conrad Hyde (2005-04-01). “Litterbug World”. Alternet. (http://www.alternet.org/story/21651/litterbug_world)



Composition_LargeComposition is the conclusion that just because an element of something has a certain property, that the larger thing must also have that same property. Composition is the converse of Division.

Pretend it’s 2005 for a moment, you’re at home with a bunch of friends, you’re all in front of the TV with your popcorn and your soda and you’re watching the ABC series Lost. Still shaken from the terrifying revelation that Ethan was not on the plane, when suddenly John Locke and Boone uncover the hatch! In this moment of passion, if one were to proclaim that Lost will quite clearly be one of the best TV shows ever written, they would have fallen for Composition. It would have been better to concluded that this episode is the best, and in no way is that a predictor for the gnarled mess to come. Okay, so this isn’t the best example. Quality is subjective yada, yada, and for someone out there, Lost is the best show ever written, but we all know that they are wrong. Breaking Bad.

Better Examples:

Oxygen is a gas*, and hydrogen is a gas*, therefore H2O is a gas*.

Swallowing a piece of gum is harmless, therefore swallowing a box of gum is harmless.

If I let my dog poop on the sidewalk, my life will be easier. Therefore, if everyone lets their dog poop on the sidewalk, everyone’s life will be easier.


*When outside at room temperature/sea level/on earth. (All three elements listed can be either gas or liquid depending on their temperature and the pressure they are under. Thanks James for spotting this!) https://en.wikipedia.org/wiki/Phase_transition



Division_LargeDivision is the conclusion that just because something has a certain property, that all its parts must also have that same property. Division is the converse of Composition.

In many cases, it is necessarily true that smaller things have the same characteristics as what they make up. The percentage of chocolate in a bag of m&ms is the same as in a single m&m for instance. But the amalgamate color of a bag of m&ms(er brownish vomity?) does not translate to each little candy.


Corporation X is unscrupulous in its business practices.

Therefore, everyone working for Corporation X has no morals.


San Francisco has the most expensive rents in the United States.

Therefore, my San Francisco apartment is more expensive than one in Manhattan.



Ad Hominem

Ad_Hominem_LargeAd Hominem is a personal attack on an opponent rather than an attack on their argument.

This informal fallacy is arguably one of the most prevalent bad arguments. It is used to discredit an opponent and distract from the subject of debate. It can imply an arguer’s position is irrelevant because of some personal flaw, or that their position is bias because of personal beliefs, or the potential for personal gain.


“My opponent argues that investing in little hats for animals doesn’t make sense. But, how can you trust someone who has such a poor history with his own personal finances?”

“Obviously you’d say that! You’re a bleeding heart liberal with no sense of practicality!”

“Of course library employees want more money for the local library system. It means they’ll have more room in their budget for raises.”


Red Herring

Red_Herring_LargeA Red Herring is a distraction used to avoid or derail an argument, often designed to appear logical. It is also the term for a misleading direction in a story.

Lets say we’re having a discussion about how worthwhile it is to be vegetarian. You say it’s better for the environment, and healthier for you, and doesn’t involve the unethical treatment of animals. Then I say that any distinction between living things is sticky and thus eating any living is equally unethical, additionally ethics are subjective.

If I said this, I would have used a red herring. My argument has nothing to do with how worthwhile it is to be vegetarian. My argument is simply a lame diversionary tactic.


Sam – “Charlie, why did you steal that banana?”

Charlie – “Stealing is an artificial construct. Everything on the earth belongs to everyone, you just don’t see it.”


The origin story goes; While training hunting dogs, hunters would drag a red stinky smoked fish  across the scent trail to distract the dogs eventually training them to follow the original scent and ignore competing stronger scents.

As it turns out,  references to this practice are red herrings in the other scents er… sense. It turns out , it was a story of distracting hunting dogs that was used only as a device  to describe a  distracting (and false) report of Napoleon’s defeat in 1807. Hunters did no such thing.

Quinion, Michael (2002–2008). “The Lure of the Red Herring”.World Wide Words.(http://www.worldwidewords.org/articles/herring.htm)


The Conjunction Fallacy

The_Conjunction_Fallacy_LargeWhich is more probable?

A: You decide to move to Greenland tomorrow.

or B: Tomorrow, you receive a phone call from an old friend who is in the same line of work you are in and he is currently living in Greenland working on an amazing project and needs your help and offers you a sweet job! Like the once in a lifetime job opportunity you simply cannot pass up, pays great, tons of vacation time, very rewarding, all that stuff. Later that evening after giving it some serious thought and talking it over with your surprisingly supportive friends and loved ones you decide that you are going to take the job and move there.

If you said B, you’d have fallen for The Conjunction Fallacy.

The Conjunction Fallacy occurs when someone assumes a more specific set of things is more probable than a more broad set of things. 

Probably the most famous example of this fallacy is from Tversky and Kahneman.

Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.

Which is more probable?

  1. Linda is a bank teller.
  2. Linda is a bank teller and is active in the feminist movement.

(Number 1 obviously, but I’m really rooting for number 2!)

Tversky, A. and Kahneman, D. 1982. “Judgments of and by Representativeness”, Pp 84-98 in Kahneman, D., Slovic, P., and Tversky, A., eds. Judgment under uncertainty: Heuristics and biases. New York: Cambridge University Press.



The Hot Hand Fallacy

The_Hot_Hand_Fallacy_LargeThe Hot Hand Fallacy is the assumption that wins or losses in games of chance exist in streaks.

While gambling, some people will feel they are having an ‘cold night’ or that ‘someone is really on tonight’, assuming luck exists as an etherial vein you can tap into as opposed to a series of independent events.

Humans are excellent at seeing patterns in what is really just noise. This is known as the ‘clustering illusion.’ Randomness is clumpy er clustery.

In basketball it is a common belief that when a player makes a basket, they will be more likely to make another basket, and another and another. This is untrue. Each basket a player makes is a statistically distinct event and thus has no effect on future baskets. Sports = arbitrary :)

This fallacy is the cousin of the ‘Gambler’s Fallacy’ which also preys on peoples misunderstanding of statistical independence.




The Masked Man Fallacy

The_Masked_Man_Fallacy_LargeThe Masked Man Fallacy is when an intensional statement is confused with an extensional statement, and a false conclusion is reached.

Intensional – Something that MUST be true about something.

Extensional – Something that IS POSSIBLE to be true about something.

I know, super confusing, a total brain melter. I apologize. Here is a  soothing example.



The kid with the baseball cap ‘s name is Sammy.

The homeowner thinks the kid with the baseball cap egged his house last night.

Therefore, the homeowner thinks Sammy egged his house last night.

In the conclusion ‘kid with the baseball cap’ was substituted with ‘Sammy’, this is wrong because in these statements the homeowner doesn’t necessarily (intentionally) know the kid’s name. So he thinks nothing of Sammy, only the sweet revenge he’s planning for that little turd in the baseball cap.