Thursday, March 19, 2009

FALLACIES:

1. Fallacy: Hasty Generalization

This fallacy is committed when a person draws a conclusion about a population based on a sample that is not large enough. It has the following form:

  1. Sample S, which is too small, is taken from population P.
  2. Conclusion C is drawn about Population P based on S.

2. Fallacy: Gambler's Fallacy

The Gambler's Fallacy is committed when a person assumes that a departure from what occurs on average or in the long term will be corrected in the short term. The form of the fallacy is as follows:

  1. X has happened.
  2. X departs from what is expected to occur on average or over the long term.
  3. Therefore, X will come to an end soon.

3. Fallacy: Biased Sample

This fallacy is committed when a person draws a conclusion about a population based on a sample that is biased or prejudiced in some manner. It has the following form:

  1. Sample S, which is biased, is taken from population P.
  2. Conclusion C is drawn about Population P based on S.

4. Fallacy: Relativist Fallacy

The Relativist Fallacy is committed when a person rejects a claim by asserting that the claim might be true for others but is not for him/her. This sort of "reasoning" has the following form:

  1. Claim X is presented.
  2. Person A asserts that X may be true for others but is not true for him/her.
  3. Therefore A is justified in rejecting X.

5. Fallacy: Genetic Fallacy

A Genetic Fallacy is a line of "reasoning" in which a perceived defect in the origin of a claim or thing is taken to be evidence that discredits the claim or thing itself. It is also a line of reasoning in which the origin of a claim or thing is taken to be evidence for the claim or thing. This sort of "reasoning" has the following form:

  1. The origin of a claim or thing is presented.
  2. The claim is true(or false) or the thing is supported (or discredited).

6. Fallacy: Guilt By Association

Guilt by Association is a fallacy in which a person rejects a claim simply because it is pointed out that people she dislikes accept the claim. This sort of "reasoning" has the following form:

  1. It is pointed out that people person A does not like accept claim P.
  2. Therefore P is false

7. Fallacy: Composition

The fallacy of Composition is committed when a conclusion is drawn about a whole based on the features of its constituents when, in fact, no justification provided for the inference. There are actually two types of this fallacy, both of which are known by the same name (because of the high degree of similarity).

The first type of fallacy of Composition arises when a person reasons from the characteristics of individual members of a class or group to a conclusion regarding the characteristics of the entire class or group (taken as a whole). More formally, the "reasoning" would look something like this.

  1. Individual F things have characteristics A, B, C, etc.
  2. Therefore, the (whole) class of F things has characteristics A, B, C, etc.

8. Fallacy: False Dilemma

A False Dilemma is a fallacy in which a person uses the following pattern of "reasoning":

  1. Either claim X is true or claim Y is true (when X and Y could both be false).
  2. Claim Y is false.
  3. Therefore claim X is true.

This line of "reasoning" is fallacious because if both claims could be false, then it cannot be inferred that one is true because the other is false. That this is the case is made clear by the following example:

  1. Either 1+1=4 or 1+1=12.
  2. It is not the case that 1+1=4.
  3. Therefore 1+1=12.

In cases in which the two options are, in fact, the only two options, this line of reasoning is not fallacious. For example:

  1. Bill is dead or he is alive.
  2. Bill is not dead.
  3. Therefore Bill is alive

9. Fallacy: Two Wrongs Make a Right

Two Wrongs Make a Right is a fallacy in which a person "justifies" an action against a person by asserting that the person would do the same thing to him/her, when the action is not necessary to prevent B from doing X to A. This fallacy has the following pattern of "reasoning":

  1. It is claimed that person B would do X to person A.
  2. It is acceptable for person A to do X to person B (when A's doing X to B is not necessary to prevent B from doing X to A).

This sort of "reasoning" is fallacious because an action that is wrong is wrong even if another person would also do it.

It should be noted that it can be the case that it is not wrong for A to do X to B if X is done to prevent B from doing X to A or if X is done in justified retribution. For example, if Sally is running in the park and Biff tries to attack her, Sally would eb jsutified in attacking Biff to defend herself. As another example, if country A is planning to invade country B in order to enslave the people, then country B would be justified in launching a pre-emptive strike to prevent the invasion.

10. Fallacy: Appeal to Common Practice

The Appeal to Common Practice is a fallacy with the following structure:

  1. X is a common action.
  2. Therefore X is correct/moral/justified/reasonable, etc.

The basic idea behind the fallacy is that the fact that most people do X is used as "evidence" to support the action or practice. It is a fallacy because the mere fact that most people do something does not make it correct, moral, justified, or reasonable.

An appeal to fair play, which might seem to be an appeal to common practice, need not be a fallacy. For example, a woman working in an office might say "the men who do the same job as me get paid more than I do, so it would be right for me to get paid the same as them." This would not be a fallacy as long as there was no relevant difference between her and the men (in terms of ability, experience, hours worked, etc.). More formally:

  1. It is common practice to treat people of type Y in manner X and to treat people of type Z in a different manner.
  2. There is no relevant difference between people of type Y and type Z.
  3. Therefore people of type Z should be treated in manner X, too.

This argument rests heavily on the principle of relevant difference. On this principle two people, A and B, can only be treated differently if and only if there is a relevant difference between them. For example, it would be fine for me to give a better grade to A than B if A did better work than B. However, it would be wrong of me to give A a better grade than B simply because A has red hair and B has blonde hair.

There might be some cases in which the fact that most people accept X as moral entails that X is moral. For example, one view of morality is that morality is relative to the practices of a culture, time, person, etc. If what is moral is determined by what is commonly practiced, then this argument:

  1. Most people do X.
  2. Therefore X is morally correct.