Fallacy of opposition

A fallacy of opposition occurs when someone assumes that:


 * Those who disagree with (oppose) you must be wrong and not thinking straight, or
 * "I would not believe something that is not true; I believe [this]; therefore, [this] must be true."

Though knowledge of reality cannot be certain, the fallacy of opposition makes people certain that they are privy to the unknowns of the Universe. Even those who are the most confident in their opinions can be totally wrong, and their opponents can be right.

The fallacy is essentially circular logic; the argument properly breaks down to "I am right, because I am right."

Carrying this ideology through to its conclusion would make someone totally impervious to the outside world; lower levels of the fallacy of opposition result in a closed mind.

Alternate names

 * Autistic certainty (no relation to autism; "autistic" here means "self-generated without reference to external reality")
 * Fallacy of self-confidence
 * Invincible ignorance

Fallacy of prejudice
The related fallacy of prejudice occurs when the quality of an argument is judged based on whether or not the listener agrees with its conclusions. If the listener agrees, the argument is good; if the listener disagrees, the argument is bad. This line of thinking is clearly fallacious — it is entirely possible that two people agree on something for different reasons or for bad reasons. Or more formally:

This style of thinking is related to substituting explanation for premise, in which a bad explanation is taken as proof that the event which is explained did not occur.

Intelligent design
In the article Teaching Intelligent Design as Religion or Science?, William Dembski writes:

In other words, people that do not consider ID to be scientific are themselves using wrong argumentation according to Dembski.

Hallucination
Many people experiencing hallucinations consider said hallucinations to be reality, without consideration of whether said hallucinations contradict other knowns, and may lead people into dangerous actions.

Knights and Knaves
A logical puzzle made popular by the logician take place on the fictional "Island of Knights and Knaves", which is populated only by Knights (who always tell the truth) and Knaves (who always lie), and in which you must ask questions to the locals in a smart way to solve the puzzles.

Of course nobody really thinks that the world consists of knights and knaves in Smullyan's sense. But unconsciously falling into this trap is a real danger in highly controversial areas, such as the creation-evolution debate. This fallacy may take the form of "an evolutionist said that, so it must be wrong" or vice versa.

Hitler
The classical example of this fallacy: Adolf Hitler argued in My Struggle (Mein Kampf) that the antisemitic hoax The Protocols of the Learned Elders of Zion must be genuine because the Frankfurter Zeitung, a paper he disliked, said the Protocols were fake. The Frankfurter Zeitung opposed Hitler's ideas, and so in Hitler's eyes, everything they said was false.

Ironically, because of the atrocities he committed, Hitler has become a sort of ultimate knave in the eyes of most people today, and it has become quite common to commit this fallacy by invoking a (real or imagined) resemblance of an opponent's position to one that was held by Hitler or the Nazi Party.