Fallacies

A fallacy is a defect in an argument other than its having false premises. Fallacies are divided into two types: formal and informal. A formal fallacy is a fallacy that can be identified by inspecting the form of the argument. Any argument that has an invalid form has committed a formal fallacy. For example: "All A are B; all A are C; therefore all B are C" contains a formal fallacy. An informal fallacy is a fallacy that, in order to be identified, requires an analysis of the content of the argument and not just an inspection of the form of the argument. For example, "George Bush is no friend of mine; no friend of mine is a Chinese communist; therefore, George Bush is a Chinese communist." While it may appear to have a valid form, it is clearly fallacious. Because detecting the fallaciousness of this argument depends on understanding the contentÐ'--in particular the meaning of "no friend of mine"Ð'--the argument contains an informal fallacy.

Informal fallacies can be classified in a number of ways. This list contains 22 informal fallacies, divided into five groups: fallacies of relevance, weak induction, presumption, ambiguity, and grammatical analogy. Note: Your text lists others as well as variant names for some of these. Don't get confused. J

Fallacies of relevance apply to arguments with premises that are not logically relevant to the conclusion but that are psychologically relevant to the conclusion in such a way as to make the conclusion appear to follow from them. The eight fallacies of relevance are:

Appeal to forceÐ'--when the arguer, instead of providing genuine evidence for a conclusion, uses some sort of threat of harm to the listener if the conclusion isn't accepted. "If you don't accept my argument, I'll punch you."

Appeal to pityÐ'--when the arguer, instead of providing genuine evidence for a conclusion, attempts to get the conclusion accepted by evoking pity from the listener. "If you don't give me a raise, my 12 children will starve to death."

Appeal to the peopleÐ'--when the arguer, instead of providing genuine evidence for a conclusion, tries to get the conclusion accepted by playing on the listener's desire to be loved, esteemed, admired, recognized, or accepted by others.

Argument against the personÐ'--when one arguer directs his or her attention to the character of the second arguer, rather than to the second arguer's argument.

AccidentÐ'--when a general rule is wrongly or unjustifiably applied to a specific case.

Straw manÐ'--when an arguer distorts someone else's argument for the purpose of more easily attacking it, refutes the distortion (the straw man) and then concludes that the real argument has been refuted.

Missing the pointÐ'--when the premises of an argument lead (or seem to lead) to one conclusion and then a completely different conclusion is drawn.

Red herringÐ'--when an arguer diverts the attention of the listener by going off on extraneous issues and points, but ends by assuming that some conclusion relevant to the point at hand has been established.

When fallacies of weak induction are committed, the defect in the argument that makes the argument fallacious is not that the premises are logically irrelevant to the conclusion, as with fallacies of relevance. Rather, the defect is that the connection between the premises of an inductive argument and its conclusion is not strong enough to make the conclusion very likely. In effect, then, the fallacies of weak induction are simply weak inductive arguments.

Appeal to unqualified authorityÐ'--when the arguer cites the testimony or belief of an authority who either is not reliable or is not an expert on the subject.

Appeal to ignoranceÐ'--the premises state that nothing is known for certain about a subject, and the conclusion states something definite about that