Sunday, August 26, 2007

Logical Fallacies

The invaluable New England Skeptical Society has a great article on their website that innumerates the logical fallacies that people, all people, are liable to hear and make. In my attempt to commit all of them to memory and internalize them, I am going to provide them here, each on with an example that I have actually heard in real life or, in the absence of such, a common example. Enjoy them and think of these fallacies the next time some poor misguided person tries to make you believe something that makes no sense.


My face looks puffy today because I went to sleep with the fan on.
Magical Thinking
This root/stem/noodle will make you live a long time because it is
Argument from Authority

Why would the Korean government restrict/ban US beef imports if there were nothing wrong with them?
Appeal to Common Belief

Everybody knows hot spices make greasy food less greasy and kill bacteria.
Appeal to Impending Acceptance

American corporation Lone Star Funds bought Korea Exchange Bank after the Asian Economic Crisis when the bank was in serious risk of going bankrupt. They turned it around and sold it for a large profit. Some in the Korean Assembly and the Prosecutor's office were incensed by the thought of foreigners making profits on Korea's misfortunes, and attempted to prosecute the company on stock manipulation charges. Frequently throughout this period people would defend the investigation by saying "They're under investigation, soon they'll be prosecuted, so of course they're guilty." (see also Argument from authority, Appeal to emotion, Argument from Conspiracy, Argument from benefit)
Appeal to Virtue or Sincerity

She means well and just wants to help, so why don't you let her give you acupuncture on the tips of your fingers and the incredibly sensitive areas right behind your cuticles?
Argument from Conspiracy or Anti-authority

The Korean government recently closed government offices to media, which had previously had free run of all government buildings, roaming the halls with cameras and demanding interviews on the spot. They also consolidated the forty-odd press rooms they operated into a few big ones. The media reported this as a bid by the government to destroy the fourth estate and return Korea to dictatorship-like state where the government has a stranglehold on the press. the government, for its part, claims that the exorbitant price of having press rooms in every government building was prohibitive and they want to save money by consolidating those rooms.
Appeal to Emotion

People are inherently good, because it would be a horrible world to live in if that weren't so.

Argument from Final Outcome or Consequences
Oriental Medicine is real because it handles all the things that Western Medicine can't do anything about, like back pain and fatigue.

Argument from Benefit

The Bush administration must be responsible for the September 11th attacks because it allowed them to seize unprecedented power.

Appeal to Fear

Korean farmers often use the fear of disease and contamination to justify trade barriers that allow them to uneconomically persist in their vocations. Note, however, that some of these fears (i.e. fear of contaminated food from China) turn out to have been well grounded.

Appeal to Flattery

People who drive hybrid cars are smarter or better than other, more polluting people.

Appeal to Pity

The clearest large-scale example of the appeal to pity is applied to the comfort women who were enlisted to sexually service Japanese soldiers during World War II. Any serious enquiry into the question of whether they were forced into servitude or whether they went willingly is effectively shut off through appeals to pity.

Post-hoc Ergo Propter Hoc (A preceded B, therefore A caused B)

I took Oriental medicine, had acupuncture, and after a month my chronic stress-related sluggishness went away. Oriental medicine cured me.

Confusing Correlation with Causation

"Long ago we lived in homes of red earth and we didn't have skin conditions, so if you use sheets dyed with red earth, you won't get skin problems."

One of the most interesting correlation/causation arguments I've heard is the one against the book "The Seven Habits of Highly Effective People". We don't know whether the habits are causing the effectiveness or if both phenomena are by-products of some root cause.

Special Pleading, or Ad-hoc Reasoning

Well of course that wish didn't come true, you didn't believe in it
enough. You gotta believe!
This is a special favorite of John Edward and other psychic mediums, who claim all sorts of 'interferences', 'static' and communications difficulties as the reasons for inaccurate readings.

Argument from Prior Error
Scientists used to think that pesticides were healthy when in fact they held health risks, therefore we shouldn't trust what they say about genetically modified foods.

Ad Hominem

Al Gore is stiff and boring. Michael Moore/Rush Limbaugh are fat. George Bush is dumb. Dick Cheney is oily and cold. Lynn Cheney is married to Dick Cheney. All the Republican presidential candidates are divorced. Joh Edwards gets expensive haircuts.

Tu Quoque

America is not without sin, so it is inappropriate for America's congress to condemn Japan for refusing to cop to its wartime offenses.

This is also used by Oriental Medicine proponents a lot.

Ad Ignorantum (Something is true because we don't know that it's not true)

Dog meat gives you vitality because it has good protein. What, it
doesn't? It's still awesome, I can feel it.

Confusing Absence of Evidence with Evidence of Absence
The galling thing about this fallacy is that many times the people using it are claiming an absence of evidence when evidence in fact exists. The best example I can think of is "There are no transitional fossils from dinosaurs to birds/apes to man/fish to land dwelling creatures." Creationists use this argument all the time in conjunction with the moving goalpost ("Show me the transitional fossil between ape and that transitional fossil!")

Argument from Personal Incredulity
Evolution is impossible. I can't see how a monkey could turn into a

Appeal to Ridicule

You're telling me that cow flatulence could somehow produce enough methane to contribute to global warming? Cow farts?! Yuk yuk yuk!

Confusing Currently Unexplained with Unexplainable
This is also known as the 'God of the Gaps' fallacy, i.e. whatever is
unexplained is the province of God. What happens after we die? Must be heaven, because science provides no answers to this question.

False Dichotomy
The Goguryeo kingdom is either part of Chinese history or part of Korean history. It can not be included in both, because to allow the other side to claim it as their own would imply that it is not one's own.

False Continuum
Everybody has an opinion and all opinions are equally valid in all situations, and so we have to respect people whose opinions are different from our own, even in issues such as science in which opinions matter less than testable hypotheses and established facts.

The Moving Goalpost

You're saying that you have proof that sleeping with a fan in the room will not eat all the oxygen and kill you, nor will it 'supermix' the air so that you consume the oxygen too fast and suffocate? Well, it still can give you hypothermia, even in the summer. Oh, it can't? Well, it'll give you a sore throat. And make your body swell. (See also special pleading)

(I realize this is a little different from the original meaning of the moving
goalpost, in which increasingly elaborate proof is demanded, but in this case
the thing proved is moving, so it seems to me the term should still be

Reductio Ad Absurdum
If we allow gay marriage, we will have to allow people to marry anyone or thing, resulting in marriage to animals and inanimate objects.
False Analogy
Vietnam and Iraq often form a false analogy for many reasons. The
different natures of the civil wars in Vietnam and Iraq, the way that
America got involved in each conflict, and of course the number of parties involved, the stakes, and the global climate at each time are substantially different. That's not to say that the analogy must always be false, as it may actually be fairly accurate in terms of the political climate in the US, in reference to which the Vietnam-Iraq War analogy may be useful.
Incidentally, there are many other lists of logical fallacies available on the web. This one is incredibly extensive and has lots of nifty latinisms, like argumentam ad misericordiam for appeal to pity, as well as a few that are not included here, such as the appeal to nature (natural things are inherently good) and red herring (introduction of irrelevent facts).
I encourage you strongly to check out the full article by Dr. Steven Novella. He is a very smart man (argument from authority) doing a lot of good work for the skeptical movement (appeal to virtue) and I know a smart person like you will be able to get the most out of these tools for rational thought (appeal to flattery).

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