Logical Reasoning: Flaws, Methods, and Parallelism on the LSAT

Flaw in the Reasoning

A type of question that identifies errors in the logic supporting an argument's conclusion.

Conclusion

The point the author is trying to prove based on their premises.

Premises

Facts, data, or claims put forward as support for the conclusion.

Connection

The reasoning linking the premises to the conclusion.

Causation flaws

Errors in treating correlation as proof of causation.

Correlation → causation

Assuming that because X and Y occur together, X causes Y.

Reverse causation

Mistaking the direction of causation in a correlation between two factors.

Overlooking a third factor

Failing to consider an external factor that may influence both X and Y.

Assuming the only cause

Claiming X caused Y without acknowledging other possible factors.

Sampling flaws

Broad claims made from insufficient or biased evidence.

Unrepresentative sample

Using a skewed sample to infer characteristics about a larger population.

Hasty generalization

Treating a few examples as if they represent the whole.

Conditional/quantifier confusion

Misinterpreting the conditions or quantities in a statement.

Affirming the consequent

A logical fallacy where the argument incorrectly infers the antecedent from the consequent.

Denying the antecedent

A fallacy where one assumes that the negation of the antecedent negates the consequent.

Equivocation

Using a key term in different senses to mislead or create confusion.

Analogy flaws

Relying on an analogy that is invalid or irrelevant to the conclusion.

Attacking the person

Focusing on the individual making an argument instead of the argument itself.

Method of Reasoning

Describes the strategy or structure of the argument without evaluating its validity.

Evidence → conclusion

Arguing that because certain facts are true, a specific conclusion follows.

Counterexample

Presenting an example that contradicts a general claim or rule.

Parallel Reasoning

Finding an argument that has the same logical structure as the given argument.

Flaw Template

A structured description of the flaw in reasoning found in an argument.

Modus tollens

A valid form of argument that denies the consequent to discard the antecedent.

Common Flaw Families

Recurring categories of reasoning errors found in arguments.

Modality/strength mismatch

Discrepancy in certainty levels between conclusions in the stimulus and answer choices.

Logical Operator

Words that indicate relationships in logic, such as 'if', 'only if', 'most', 'some', etc.

Premise-to-Conclusion Pattern

The specific logical connection that exists between the supporting premises and the conclusion.

Flaw in action

An illustration of how a specific flaw manifests in an argument.

Judging support logically

Evaluating if premises adequately lead to the conclusion, regardless of real-world facts.