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A '''logical fallacy''' is an error in [[formal logic|logical]] reasoning. While the common usage of the word ''fallacy'' would include ''any'' error in [[reason]]ing, in logic a fallacy is defined as a particularly [[deceit|deceptive]] argument which seems correct, but upon further examination is found to be incorrect.<ref name="copi">Copi, Irving M. and Carl Cohen. "Introduction to Logic, 12e". Pearson Education: 2005</ref>

A '''logical fallacy''' is an error in [[formal logic|logical]] reasoning. While the common usage of the word ''fallacy'' would include ''any'' error in [[reason]]ing, in logic a fallacy is defined as a particularly [[deceit|deceptive]] argument which seems correct, but upon further examination is found to be incorrect.<ref name="copi">Copi, Irving M. and Carl Cohen. "Introduction to Logic, 12e". Pearson Education: 2005</ref> The maker of such an argument, however, need not be aware of its fallacious nature.

Logical fallacies fall into two general categories: formal fallacies and informal fallacies. Formal fallacies apply to [[deductive argument]]s, and are those which relate to an improper application of a rule, whereas informal fallacies apply to [[inductive argument]]s, and are those which involve the improper use of the content of an argument.

Logical fallacies fall into two general categories: formal fallacies and informal fallacies. Formal fallacies apply to [[deductive argument]]s, and are those which relate to an improper application of a rule, whereas informal fallacies apply to [[inductive argument]]s, and are those which involve the improper use of the content of an argument.

*Therefore P is true

*Therefore P is true

For example: "If you do not pay me $30 I will break your leg. Therefore you owe me $30."

For example: "If you do not pay me $30 I will break your leg. Therefore you owe me $30." It is fallacious because no amount of force can change the truth or falsity of the initial proposition.

===Appeal to pity===

===Appeal to pity===

Also called [[emotion]]al appeal, (Lat: ''ad misericordiam'') this fallacy is characterized by a use of emotion as a justification for the conclusion. An appeal to [[pity]] follows the form:

Also called [[emotion]]al appeal, (Lat: ''ad misericordiam'') this fallacy is characterized by a use of emotion as a justification for the conclusion. An appeal to [[pity]] follows the form:

*Person A argues that P

*Person A argues P

*Circumstance Q has happened to person P

*Person B agrees P, but adds X, where X is an emotional argument unconnected to P

*Therefore P is true

 

For example: "Yes, [[police|officer]], I realize I was speeding, but you shouldn't give me a ticket because I was racing to see my wife who is in the [[hospital]]." While this argument uses an emotional appeal to convince the officer not to hand out a citation, there is no logical connection between the premise ("you shouldn't give me a ticket") and the conclusion ("I was racing to see my wife").

For example: "Yes, [[police|officer]], I realize I was speeding, but you shouldn't give me a ticket because I was racing to see my wife who is in the [[hospital]]." While this argument uses an emotional appeal to convince the officer not to hand out a citation, there is no logical connection between the premise ("you shouldn't give me a ticket") and the conclusion ("I was racing to see my wife").

Appeals to pity are very commonly seen in business. A factory manager may make the following argument: "our factory's overheads are too high, and we cannot maintain our business if we continue here. Therefore we should relocate to an area where labour is cheaper." An appeal to pity would be of the following type: "but our workers have bills to pay, families to support, we cannot fire them." That statement may be true, but is fallacious because it is not relevant to the manager's argument.

===''Argumentum ad hominem''===

===''Argumentum ad hominem''===

*Therefore P is false

*Therefore P is false

For example: "We all know that George beats his wife, so obviously he's wrong when he says that we should vote against this proposition." This is fallacious reasoning because the premise ("George beats his wife") does not have a logical link with the conclusion ("George is wrong").

For example: "We all know that George beats his wife, so obviously he's wrong when he says that we should vote against this proposition." This is fallacious reasoning because the premise ("George beats his wife") does not have a logical link with the conclusion ("George is wrong"). Whatever undesirable qualities a person may have, they do not affect the truth or falsity of what he says.

====''Ad hominem tu quoque''====

====''Ad hominem tu quoque''====