We often make legitimate appeals in support of arguments. For example, to support a statement about the relationship between energy and mass, Danielle might appeal to Albert Einstein's theories as an authoritative source. To support a claim dealing with guns and gun control, Janelle might appeal to the Bill of Rights. And to support an argument on immigration, Claudelle might appeal to the humanity or generosity of her audience. As long as Einstein is an authority on Danielle's topic, as long as the Bill of Rights deals with Janelle's topic, and as long as the generosity of her audience is directly related to Claudelle's topic, each of these appeals would be perfectly acceptable.
However, what if Danielle had appealed to Einstein as an authority on rap music, or if Janelle had used the Bill of Rights to support a claim about which store has the best prices, or if Claudelle had appealed to the generosity of the judges in evaluating her performance in gymnastics? We would probably have a puzzled reaction, since these appeals would seem to have little or nothing to do with the claims they were used to support.
The problem is that fallacious appeals are not always as obvious as these last three, and it necessary for the critical thinker to determine, in each case, whether an appeal is appropriate or not. Generally speaking, fallacious appeals can be divided into two groups: misdirected appeals and emotional appeals.
In a misdirected appeal, an otherwise legitimate appeal is misapplied by being used to support an unrelated claim. Danielle's use of Einstein, who was an authority but not on rap music, and Janelle's use of the Bill of Rights, which guarantees some things but not which store has the best prices, are examples of misdirected appeals.
By itself, an emotional appeal is never a legitimate strategy in an argument, because it is based on emotions rather than verifiable or evaluative support. Claudelle's appeal to the generosity of her audience in an argument about immigration, for example, would be appropriate as long as she was discussing that generosity as a value related to the subject. However, an appeal to the generosity of the judges at a gymnastic meet is merely a play on their emotions (probably an appeal to their pity); anyway, the value of generosity has nothing to do with the evaluations the judges would render. Thus, Claudelle's appeal to the judges' generosity would be a fallacious emotional appeal.
The following are some of the most common fallacious appeals. Popular variations on the names are listed following the link.