A recent discussion on a web forum has lead me to digging through my old Philosophy resources, and I found a rather nice listing of the common formal fallacies.
Fallacy:
a mistaken inference, faulty reasoning; a seemingly reasonable argument which is actually unsound.
Ad Hominem:
a fallacy of reasoning in which a speaker attacks the personality of her opponent and not the issues argued by the opponent. Perhaps the best example of this can be seen in the 1992 Presidential election in which President George Bush spent most of his campaign focusing on Governor Bill Clinton’s character and not Clinton’s platform. Debaters using this approach are considered to be unethical and judges should give little importance to the value statements of the slandered debater’s character. Hence, the judge should formulate a decision based upon the issues in the round and drop the unethical debater.
Ad Verecundiam:
the argument of appealing to tradition as a rationale for adopting a position or opinion. For example, we should do it this way because we have always done it this way. While it is possible for tradition to be a valid rationale for adopting a position, it is necessary for the speaker to demonstrate the rationale behind the tradition other than “we have always done it this way.” We use to scandalize divorcees, but now we make
television shows about them.
Ad Populum:
known as the appeal to the people. If the majority thinks something is worthwhile then it must be. However, the will of the people may be negative or undesirable, e.g. the Jim Crow laws of the 1950s in which the majority of the people felt that segregation was an acceptable practice.
Amphibole:
the fallacy of reasoning in which language is misinterpreted or misconstrued to change the intent of the meaning. For example, a sign outside of a Wendy’s burger joint reads, “Hiring: One Day Shift,” could be interpreted as hiring one person to work in the day time or hiring a person to work one day.
Argumentum Ab Auctoritate Est Fortissimum In Lege:
a fallacy of reasoning which contends argument from authority is the strongest, but the analysis of people in power is not necessarily better than the common folk’s analysis. For example, President Clinton’s conclusions for how the government should be run are not necessarily better than those of Bob Jones, the McDonald’s worker.
Argumentum Ad Populum:
a fallacy of reasoning which holds that just because a majority of people believe a thing is right or true doesn’t mean it is right or true. For example, there was a time when a majority of people believed the sun revolved around the earth and this was taught as the truth, to preach otherwise was heresy.
Faulty Analogy:
a fallacy of reasoning in which an inappropriate comparison is made. For example, comparing nurses to prostitutes because they both care for the ill, comparing apartheid to social control, comparing the KKK to a Kiwanis or Rotary Club, or comparing Dan Quayle to John Kennedy. Such comparisons are inadequate because there are not enough similarities between the items compared and the comparison drawn is colored by a biased or prejudiced view.
Hasty Generalization:
a fallacy of reasoning in which a generalized conclusion is made from a sample which is too small to make such a conclusion from. For example, two out of three doctors may recommend Trident chewing gum, but that doesn’t mean all doctors do; just because a riot breaks out at a rock concert doesn’t mean riots break out at all concerts; just because some rock music is wicked and evil, doesn’t mean all rock music is wicked and evil. Still, it is necessary for speakers to draw conclusions from limited samples or situations; therefore, it is necessary to have some method or standard for determining what is a sufficient sample size. Two such standards exist: numerics and significance. Numerics holds there must be three to five examples which reach the same conclusion before the conclusion can be considered a valid generalization. Significance argues that the most important issue to look at is sufficient enough to base a conclusion on. The problem, however, is in establishing the issue as the largest in scope in terms of who is affected and how those people are affected.
Non Sequitur:
a reasoning fallacy in which either the claim or argument being made does not address the issues or evidence in question. For example, the evidence not meeting the tag line (tag: millions will die without Justice, card: Justice is important), or arguing that individuals should respect the rights of others in support of social control.
Post Hoc Ergo Propter Hoc:
because one event happens after another, the first happening was the cause of the second. For example, just because a famine occurred after the Seattle Seahawks finally won a football game does not mean the win caused the famine.
Reductio Ad Absurdum:
a fallacy of reasoning in which the method of disproving an argument is by showing that it leads to absurd consequence. For example, a speaker claiming society must be more matriarchal could be refuted by showing this shift would cause a major collapse of the economic system because the female perspective is too cooperative and caring…which is clearly absurd!
Significance (Fallacy):
is a fallacy of reasoning in which people assign and accept the importance or power of something without knowing all of the details. For example, people accept the idea that nuclear energy is inherently evil and detrimental to the environment without questioning the scientific base for this conclusion.
Strawman:
also known as a red herring, is the reasoning fallacy in which an issue is made to be bigger or more important than it actually is to distract from the truly important or real issues in the round and is usually omitted in rebuttals by the exploiting speaker. This strategy makes it difficult for an opponent to make a cohesive attack and forces the judge to base a decision on the real issues that are finally identified, if at all, in the last rebuttal when there is no time for adequate development or clarification.