Underpinnings of Informal Fallacies

December 12th, 2009

Informal fallacies

The types of mistakes in reasoning that arise from the mishandling of the content of the propositions constituting the argument.

Ad hoc Using an off-the-cuff explanation with no evidentiary support.
Ad hominem Attacking the opponent directly rather than addressing the opponent’s idea.
Ambiguity Ambiguity occurs when linguistic ambiguity causes the form of an argument to appear validating when it is not.
Argument by assertion The belief that if you say a thing enough times, it becomes true and you win the argument.
Argumentum ex culo Making things up.
Argument from ignorance Basing the truth of a premise only on whether it has been proved to your satisfaction.
Argument from incredulity Literally “that’s unbelievable = that’s obviously not real”. This kind of thinking would quickly put an end to virtually all quantum physics.
Argument from adverse consequences Arguing against a point based on expected negative outcome.
Argument from authority Because someone famous/powerful/respected believes it, it must be true.
Association fallacy Associating the values of one group with the values of another due to superficial or co-incidental similarities.
Balance fallacy Giving equal weighting to both sides of an argument, even if one really doesn’t deserve the time.
Begging the question Assuming the conclusion as part of the premise (similar to circular reasoning).
Bullshit Deceit through obfuscation.
Correlation does not equal causation Two events can consistently correlate with each other but not have any causal relationship.
Equivocation Deliberately substituting the meaning of a given word in one context for another that is inappropriate to make your argument.
False analogy Creating an analogy or metaphor, then extending it to prove one’s point.
False dilemma Portraying two options as the only possibilities, with no middle ground (see Pascal’s wager for an example).
Moving the goalposts Changing evidential requirements in an argument once they have been met, “what I really meant was…”
Negative proof Arguing that something must exist because there is no evidence it does not exist.
No True Scotsman Excluding an inconveniently misbehaving member of a class to defend the class as a whole.
Non sequitur Giving an evasive or nonsensical answer to a challenge.One single proof: Dismissing all circumstantial evidence in favor of a single “smoking gun” that may not (and may not need to) exist.
Poisoning the well Attempting to refute an argument based on the perceived veracity of the presenter.
Post hoc, ergo propter hoc Saying that because event A happened before B, A must have caused B.
Red herring A group of fallacies which bring up a fact which is irrelevant to the issue.

Guilt by association: (eg: Godwin’s Law) Saying that something is bad because a bad person or group did it.
Honor by association: Saying that something is good because a good person or group did it.
My enemy’s enemy: Supporting someone because they oppose the same people
Argumentum ad baculum: Attempting to intimidate an opponent (baculum is Latin for “stick”).
Argumentum ad populum: or bandwagon — Arguing for a point based on popularity rather than merit.
Argumentum ad verecundiam: “Argument from shame”. Also see emotional appeal.

Slippery slope If event A happens, it will lead downhill to further undesirable results. For example, “if we allow gays to get married, then we’ll have to let men marry little kids”.
Spotlight fallacy Assuming aspects of a group from aspects from a smaller observed part of the group
Straw man Falsifying an opponent’s position for greater rhetorical flexibility.
Style over substance fallacy Using language or rhetoric to enhance the appeal of an argument, but not its validity.
Texas sharpshooter A data mining fallacy and pattern recognition error where the arguer makes an ad hoc conclusion from a set of unrelated data without looking for corroborating data.
Galileo gambit This states that if someone is going against the tide of popular thinking, they must be right because the likes of Galileo were right, while in reality, Galileo was right for the more simple reason that he was right.

Logic – For the love of it

Jeffrey Slee

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