Association Fallacy

""'All wood burns,' states Sir Bedevere. 'Therefore,' he concludes, 'all that burns is wood.' This is, of course, pure bullshit. Universal affirmatives can only be partially converted: all of Alma Cogan is dead, but only some of the class of dead people are Alma Cogan.""

- "A Lesson in Logic", Monty Python and the Holy Grail (Soundtrack from the Motion Picture)


 * Claiming a quality of one thing is also a quality of another thing because they have some other thing in common, e.g. "Water is a liquid. Water will put out most fires. Therefore, any liquid will put out most fires." And then you pour on the olive oil. Or the high-proof vodka.

Also called

 * Reductio Ad Hitlerum, when the association is specifically made to Hitler.
 * Reductio ad Nazium, when the association is made to the Nazis.
 * Reductio ad Communum, when the association is made to Communists.
 * Broad Brush
 * Sweeping Generalization


 * Guilt By Association assumes that two separate things share a negative factor because they share a different, unrelated factor. (See also Stop Being Stereotypical, Don't Shoot the Message)

"Stalin was evil. Stalin was an atheist Therefore atheists are evil because Stalin belonged to both groups."
 * Equating complex calendars with human sacrifice because the ancient Aztecs had a complex calendar, and also practiced human sacrifice.
 * Stalin is sometimes used by religious conservatives to prove that atheism is bad.

"Pat Robertson said crazy things about Haitian voodoo practices causing the earthquake. Pat Robertson is a Christian. Therefore Christians are crazy."
 * Hitler (who described himself as Catholic, but just how devout he was is a matter very much up for debate) is also sometimes used like this.
 * Commonly used in arguments about religion:

"They burn witches.
 * In Monty Python and the Holy Grail, they use this to prove a woman is a witch.

They burn wood.

Therefore witches must be made of wood.

Wood floats.

Ducks float.

Therefore anything that weighs the same as a duck must be made of wood.

She weighs the same as a duck.

Therefore, she must also be made of wood, and therefore, a witch."

"You give a detailed and well-researched argument on a subject. Your mother/cousin/sibling/whatever turns up his/her nose and declares, "You're acting just like (insert "know-it-all" relative here)!" OR You're doing something a family member doesn't approve of, which Your Loser Relative also happened/happens to do. Your family member declares: "You're acting just like Your Loser Relative!""
 * Of course, in this instance they were completely right.
 * You get compared to Your Obnoxious/Loser Relative, with the implication that because they aren't model citizens, whatever it is you're doing or thinking is wrong and must be stopped immediately:

""Barack Obama plays basketball. Charles Barkley plays basketball. Is Charles Barkley qualified to lead our economy?""
 * Saturday Night Live's spoof of John McCain's political ads:

"Alcohol is Bad (reasons vary as to why it's bad. Don't get into it, just accept that it's a premise of the argument)
 * Australia has banned porn that stars small-breasted women because since children have no breasts and pedophiles like children, anyone who likes small-breasted women must be a pedophile.
 * The above never actually happened outside of a press release.
 * Some teetotaller sects of Christianity maintain that Jesus never drank wine, based on logic which is sort of an inverse of this fallacy; an anti-association fallacy if you will:

Jesus is Good

Because Jesus is Good, Jesus only does and associates with Good things (again, there are flaws in the logic best left alone)

Ergo, because alcohol is Bad, Jesus never partook of it."

In order to make this work, any time wine is referenced in a positive context (for example, Jesus' first miracle), the word is instead rendered as "unfermented grape juice" when translated into English.

Reductio ad Hitlerum

 * A very common form of Guilt by Association is "Hitler did it, therefore it's bad." While persuasive, it's not always true, since while Hitler did a lot of evil things, he also was a massive advocate of animal rights (well, definitely more so than Jewish, gay, or Gypsy rights...), built motorways, painted pictures, hosted the Olympics, ate sugar, and breathed oxygen. This is related to the Fallacy of Division, since it assumes the evilness of the whole of Hitler also applies to any part of Hitler. Related to Godwin's Law and Hitler Ate Sugar.

Examples
""Y'know, Hitler was a vegetarian." "Vegetarianism then: not all it's cracked up to be. In some extreme cases may cause genocide." \\ -- Bill Bailey"
 * An anti-abortion Chick Tract claims abortion is wrong because Hitler killed Jewish babies, and therefore doctors who carry out abortions are as bad as Hitler.
 * There's an interesting inversion of this making the rounds on the internet. Whenever some distressing news is revealed to the world, someone will inevitably use the clip from Downfall where Hitler has a Villainous Breakdown upon learning that Berlin will be overrun. The person making the video will often put their words into Hitler's mouth. This is usually a case of Even Evil Has Standards, with the intended message being "Even Hitler thinks that's going too far".

Looks like this fallacy but is not

 * Similar to the above, when an example is used to establish a fact about a group in the aggregate, rather than about members of that group. For instance, noting instances of gay men who are HIV positive and concluding that gay men have higher rates of HIV is not a fallacy (assuming valid statistical techniques are used). Concluding that a particular gay man is HIV positive is a fallacy.
 * When a member of a group is presented as an example of a common feature at work, rather than proof in itself that there is a common feature. For instance, it is valid to use the 9/11 attacks and abortion-clinic bombings as examples of how radical Muslims and Christians can be evil. They are not, on the other hand, examples of how all Muslims and Christians are evil. Capiche?

Honor by Association

 * The flip side of Guilt by Association, stating that two things share a positive quality because they share a different, unrelated quality.

Examples

 * One Usenet poster who claims "we should all become vegetarian" claims in his sig that "Jesus was a vegetarian". His reasoning: vegetarianism is good; Jesus was good; therefore Jesus must have been a vegetarian. Which assumes that vegetarianism is "Good" by all standards and values of those who hold that Jesus Christ was good and that Jesus is believed to be "Good" by everyone.
 * Other people use a somewhat more complicated, but just as fallacious version of this argument: Because Jesus's teachings and behaviors were most in line with the Essene sect, Jesus must have been an Essene, and because the Essenes were mostly vegetarian (pescatarian, actually, but they leave out that part), Jesus must have been vegetarian and because Jesus is good, the vegetarianism is good and would therefore hate killing animals as much as they do. (Never mind that the Essenes weren't vegetarian out of compassion for animals, but rather because they believed anything created from sexual union was treif, but that fish spawned via abiogenesis in the waters and were therefore kosher. Of course that part gets left out, too.)
 * Some sects of Christianity that preach teetotalitarianism apply a similar fallacy to alcohol. They feel alcohol is bad, and Jesus was purest good, so he naturally would not have done anything bad. Therefore he would not have partaken of alcohol. Therefore, the same word is translated as "unfermented grape juice" in instances where it's being partaken of or otherwise addressed positively, and "wine" when speaking against the dangers of excessive drinking in their editions of the Bible. This is pretty much entirely nonsensical; grape skins are coated in yeast, and therefore keeping grape juice from fermenting with period technology is impossible. You pretty much had to own a vineyard to get fresh grape juice in those days, as the alcohol produced by fermentation was necessary to prevent spoilage.
 * Otacon states matter of factly that liking dogs is irrefutable proof that a person is decent, deep down. Snake immediately points out that Hitler was a big fan of dogs. Interesting in that while it applies under this variant, the exchange is often mistaken for an example of the Argumentum Ad Hitlerium fallacy. But Snake isn't saying liking dogs is bad; he's just shooting down Otacon's fallacy by pointing out a bad person who liked dogs.

Looks like this fallacy but is not

 * When the example is being used to show that there is overlap in the members of two groups, but not to state or imply that the overlap is total. For instance, saying "many (or even most) vegetarians are good, moral people" is not this. On the other hand, saying it might be misleading: One hopes that most people are good, moral people.