Bronze-level articleLogical fallacy

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*[[Appeal to tradition]] - Just because it's ''always'' been that way doesn't mean it's the right way.  
 
*[[Appeal to tradition]] - Just because it's ''always'' been that way doesn't mean it's the right way.  
 
*[[Argument by assertion]] - The belief that if you say something enough times, it eventually becomes true and therefore you win the argument.
 
*[[Argument by assertion]] - The belief that if you say something enough times, it eventually becomes true and therefore you win the argument.
*''[[Argumentum ad martyrdom]]'' - The assertion that you're right because you perceive the opposition to be hostile to you personally; the belief that the more people hate you, the more right you are.
 
 
*''[[Argumentum ad nauseam]]'' - The belief that something becomes true if repeated often enough to make you vomit.
 
*''[[Argumentum ad nauseam]]'' - The belief that something becomes true if repeated often enough to make you vomit.
 
*''[[Argumentum ex culo]]'' -- Making things up.  
 
*''[[Argumentum ex culo]]'' -- Making things up.  

Revision as of 14:11, 10 October 2011

Part of the series on

Logic and rhetoric

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General logic
Bad logic
A logical fallacy is, fundamentally, an error in logic. This means that an argument that uses one certainly doesn't hold if you're using logic and reason as your source of decision making - although it doesn't stop people from using them or being swayed by them. People who want to sound smart tend to use the Latin (or some cases, Dog-Latin) names to refer to them. Others, who don't care about being too diplomatic when bringing them up, will just cry bullshit and carry on. There are two forms of a logical fallacy, formal and informal.

Contents

Formal fallacies

Formal fallacies are those fallacies that violate a particular rule of propositional calculus, such as modus ponens. These fallacies can be determined to be invalid simply by the inspection of the form or structure of the argument - at heart, a formal fallacy contains some sort of non sequitur. This doesn't necessarily mean that a conclusion is wrong, but it does mean that we will need a better reason or argument to derive the conclusion.

Informal fallacies

Informal fallacies are arguments that, while not violating propositional calculus rules, are invalid because of the content of their argument. Informal fallacies are often characterised by the fact that there is a disconnect of somekind between their premises and conclusions. Inappropriate generalisations and argument from ignorance are forms or informal fallacies. These tend to be more numerous and slightly more interesting than formal fallacies.

Common examples

Common fallacies include:

  • 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; also, tu quoque, where a criticism is falsely dismissed because its author is also guilty of the charge.
  • Appeal to tradition - Just because it's always been that way doesn't mean it's the right way.
  • Argument by assertion - The belief that if you say something enough times, it eventually becomes true and therefore you win the argument.
  • Argumentum ad nauseam - The belief that something becomes true if repeated often enough to make you vomit.
  • 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.
    • Negative proof -- Arguing that something must exist because there is no evidence it does not exist.
  • 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 coincidental 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.
  • Composition and division -- A pair of fallacies confusing what is true of a part with what is true of the whole.
  • Correlation does not equal causation -- The number of pirates on the seas has gone down, this correlates with global temperatures rising. So, do pirates cause global cooling?
  • Equivocation -- Deliberately substituting the meaning of a given word in one context for another context that is inappropriate in order to make your argument.
  • Ex equus pyga -- "From the horse's ass" is a variety of argument from authority. The horse's ass claims a particular status such as former military or government service to lend weight to their assertions or imperatives. It is a supremely ineffective strategy, resulting only in the inflation of the horse's ass's own chest. Anyone who has ever tried to cinch a saddle girth tight on an unwilling animal knows that the beast is not that hard to outsmart. All it takes is patience, since sooner or later he must exhale.
  • 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).
  • The 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.
  • Generalization from fictional evidence
  • Intuition pump -- Deliberately abusing a thought experiment to prove a fallacious point.
  • Moving the goalposts -- Changing evidential requirements in an argument once they have been met, "what I really meant was..."
  • 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.
  • Overgeneralization -- Taking a few specifics and making a general rule out of them, without the few specifics adequately representing the entire group.
  • Presupposition -- Making an implicit assumption as part of a phrase.
  • 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 -- Saying that something is bad because a bad person or group did it, e.g. saying painting is evil because Hitler liked to paint (see also Godwin's law) or ties are immoral because Bush/Obama/[insert disliked male politican here] wears ties.
    • 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.
    • "Argument from shame", or "Argument by ridicule" Also see emotional appeal.
  • Reification -- Treating an abstraction as a real thing, e.g. treating the test score called "intelligence" as an innate part of a person.
  • 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.

See also

External links

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