LSAT Logical Reasoning: Mastering Assumption Questions

Necessary Assumption

A key element on which an argument must rely for its conclusion to hold; if false, the argument fails.

Causal Reasoning

Assuming a cause-and-effect relationship based on correlation or temporal order.

The Negation Test

A method to determine if a statement is a necessary assumption by negating it and assessing if the argument collapses.

Sufficient Assumption

A statement that, if added to the premises, guarantees the conclusion follows logically.

Premise vs. Conclusion

Premises provide evidence in an argument, while the conclusion is the claim that the argument seeks to prove.

New Term Gap

When the conclusion introduces an idea not established by the premises, requiring a necessary assumption.

Plans/Policies Assumption

Necessary assumptions related to recommended actions, ensuring they won't backfire and are feasible.

Sampling/Generalization Assumption

Assumption that a sample is representative of a broader group when generalizing from specific observations.

Comparison/Analogy Assumption

Assumption that two things compared are similar in a relevant way to support the argument.

Strength of Language

In sufficient assumptions, strong language can be necessary to ensure the conclusion is guaranteed.

“Must” vs. “Can”

In logical reasoning, necessary assumptions must always be true; sufficient assumptions guarantee action under conditions.

Bridge Metaphor

A useful analogy to understand necessary and sufficient assumptions: necessary are support beams; sufficient provide a complete section.

Identifying Argument Gaps

The skill of pinpointing missing elements in an argument that, if filled, would solidify the reasoning.

Weakening vs. Strengthening

Recognizing what assumptions to strengthen or weaken an argument's conclusion.

Logical Dependence

The relationship where the truth of one statement relies on the presence or absence of another.

Common Fallacies

Mistakes often made, such as confusing necessary assumptions with helpful but non-essential statements.

Combining Assumptions

Recognizing that necessary and sufficient assumptions may require integrating more than one logical step.

Direct Links in Reasoning

In sufficient assumption questions, direct connections between premises and conclusions are often necessary.

Conditional Statements

Many sufficient assumptions hinge on confirming or establishing a conditional relationship between premises and conclusions.

Absolute Guarantees

A defining feature of sufficient assumptions, ensuring the conclusion cannot be false if the assumption holds true.

Mistaken Inference

When a student assumes an argument is valid based on an inference that is not directly supported by the premises.

Causal Confounder

An alternative explanation that may undermine a causal argument; necessary assumptions often rule these out.

Quantifier Awareness

Understanding the significance of terms like 'some,' 'all,' and 'none' when forming assumptions.

Logical Support

The backbone provided by necessary assumptions that underpins the conclusion of an argument.

Anticipating Argument Flaws

The ability to foresee weaknesses in an argument by identifying its necessary assumptions.

Over-Negation

A common mistake where a student negates too strongly, potentially misidentifying necessary assumptions.