Lsat Common Errors Of Reasoning

Front 1

Uncertain Use of a Term or Concept

Back 1

As an argument progresses, the author must use each term in a constant, coherent fashion. Using a term in different ways is inherently confusing and undermines the integrity ofthe argument.

Front 2

Source Argument

Back 2

Also known as an ad hominem, this type of flawed argument attacks the person.'
(or source) instead of the argument they advance.

A source argument can take different forms, including the following:
1. Focusing on the motives of the source.
2. Focusing on the actions of the source (as in the above example).

Front 3

Circular Reasoning

Back 3

In circular reasoning the author assumes as true what is supposed to be proved.

E.g. "This essay is the best because it is better than all the others."

Front 4

Errors of Conditional Reasoning

Back 4

- Mistaken Negation e.g. "taking the nonexistence of something as evidence that a necessary precondition for that thing also did not exist"

- Mistaken Reversal e.g. "mistakes being sufficient to justify punishment for being required to justify it"

- Confuses a necessary condition for a sufficient condition e.g. "it treats something that is necessary for bringing about a state of affairs as something that is sufficient to bring about a state of affairs"

- Confuses a sufficient condition for a necessary condition e.g. "confuses a sufficient condition with a required condition"

Front 5

Mistaken Cause and Effect

Back 5

1. Assuming a causal relationship on the basis of the sequence of events.
2. Assuming a causal relationship when only a correlation exists.
3. Failure to consider an alternate cause for the effect, or an alternate cause
for both the cause and the effect.
4. Failure to consider that the events may be reversed.

Front 6

Straw Man

Back 6

Occurs when an author attempts to attack an opponent's position by ignoring the actual statements made by the opposing speaker and instead distorts and refashions the argument, making it weaker in the process.

Front 7

General Lack of Relevant Evidence for the Conclusion

Back 7

Some LSAT authors misuse information to such a degree that they fail to provide any information to support their conclusion or they provide information that is irrelevant to their conclusion.

Front 8

Internal Contradiction

Back 8

Occurs when an author makes conflicting statements e.g. "Everyone should join our country club. After all, it's an exclusive group that links many of the influential members of the community."

Front 9

Appeal Fallacies

Back 9

1. Appeal to Authority - uses the opinion of an authority in an attempt to persuade the reader. The flaw in this form of reasoning is that the authority may not have relevant knowledge or all the information regarding a situation, or there may be a difference of opinion among experts as to what is true in the case.
2. Appeal to Popular Opinion Appeal to Numbers - states that a position is true because the majority believe it
to be true.
3. Appeal to Emotion - occurs when emotions or emotionally-charged language is used in an attempt to persuade the reader.

Front 10

Survey Errors

Back 10

1. The survey uses a biased sample.
2. The survey questions are improperly constructed.
3. Respondents to the survey give inaccurate responses.

Front 11

Exceptional Case / Overgeneralization

Back 11

Takes a small number of instances and treats those instances as if they support a broad, sweeping conclusion.

Front 12

Errors of Composition

Back 12

Occurs when the author attributes a characteristic of part of the group to the group as a whole or to each member of the group.

Front 13

Error of Division

Back 13

Occurs when the author attributes a characteristic of the
whole (or each member of the whole) to a part of the group.

Front 14

False Analogy

Back 14

Occurs when the author uses an analogy that is too dissimilar to the original situation to be applicable.

Front 15

False Dilemma

Back 15

Assumes that only two courses of action are available when there may be others.