Flaw in the Reasoning Questions

Flashcards regarding flaws in reasoning as discussed in the PowerScore LSAT Logical Reasoning Bible.

Flaw in the Reasoning Questions

Questions that contain flawed reasoning in the stimulus. The question stem indicates that the reasoning in the stimulus is flawed.

Uncertain Use of a Term or Concept

Using a term in different ways as an argument progresses, which is inherently confusing and undermines the integrity of the argument.

Source Argument

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

Circular Reasoning

The author assumes as true what is supposed to be proved; the premise and the conclusion are identical in meaning.

Errors of Conditional Reasoning

Mistakes in logic that confuse necessary and sufficient conditions; include Mistaken Negation and Mistaken Reversal.

Mistaken Cause and Effect

Arguments that draw causal conclusions are inherently flawed because there may be another explanation for the stated relationship.

Straw Man

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.

General Lack of Relevant Evidence for the Conclusion

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.

Internal Contradiction

Also known as a self-contradiction, this occurs when an author makes conflicting statements.

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.

Appeal to Popular Opinion/Appeal to Numbers

This error states that a position is true because the majority believes it to be true.

Appeal to Emotion

Occurs when emotions or emotionally-charged language is used in an attempt to persuade the reader.

Survey Errors

Surveys, when conducted properly, produce reliable results. However, surveys can be invalidated when either of the following three scenarios arise: the survey uses a biased sample, the survey questions are improperly constructed, respondents to the survey give inaccurate responses.

Exceptional Case/Overgeneralization

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

Errors of Composition and Division

Composition and division errors involve judgments made about groups and parts of a group. An error of composition 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. An error of division occurs when the author attributes a characteristic of the whole (or each member of the whole) to a part of the group.

False Analogy

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

False Dilemma

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

Errors in the Use of Evidence

Mis-assessing the force of evidence is a frequent error committed by LSAT authors. Examples include, lack of evidence for a position is taken to prove that position is false, lack of evidence against a position is taken to prove that position is true, some evidence against a position is taken to prove that position is false, some evidence for a position is taken to prove that position is true

Time Shift Errors

The mistake involves assuming that conditions will remain constant over time, and that what was the case in the past will be the case in the present or future.

Numbers and Percentage Errors

Many errors in this category are committed when an author improperly equates a percentage with a definite quantity, or when an author uses quantity information to make a judgment about the percentage represented by that quantity.