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Practice LSAT Arguments, Assumptions, and Evidence
Logical Reasoning asks you to analyze, critically evaluate, and complete arguments. This public teaching page focuses on the moves that make a short argument work: locating the conclusion, separating it from its support, and identifying the missing link or vulnerable inference.
The examples below are original teaching exercises, separate from protected prediction reports and from official LSAT questions. Use them to explain your reasoning in a sentence before checking feedback; that habit makes a miss more useful than simply seeing the correct letter.
Practice the skill, then review the reasoning
A manager concludes that a shorter checkout form will increase completed purchases because customers often abandon a form after seeing many required fields. Which assumption is required by the argument?
A town concludes that its new weekend shuttle caused an increase in downtown visitors because visitor counts rose after the shuttle began. Which fact most weakens the conclusion?
A college says: “Any student who completes the research workshop may reserve the advanced lab. Kai may reserve the advanced lab. Therefore, Kai completed the workshop.” What is the flaw?
Start with the claim to be proved
An argument has a conclusion and support. The conclusion is the claim the speaker wants accepted; the support is the material offered as a reason for it. A conclusion may be a recommendation, a prediction, or a judgment. It is not necessarily the last sentence, although it often is.
Try a quick paraphrase: “The speaker concludes X because Y.” If the sentence still represents the passage fairly, X is likely the conclusion. This keeps a vivid statistic, example, or concession from being mistaken for the point of the argument.
Spot the bridge an argument leaves unstated
An assumption is a claim the argument takes for granted. A necessary assumption must hold for the reasoning to remain viable. If you negate it and the argument loses its support, you have found a needed bridge between premise and conclusion.
A sufficient assumption does more. Added to the premises, it guarantees the conclusion. It can sound stronger than a necessary assumption because it has to close every remaining gap. Before inspecting choices, say what is known and what the conclusion newly asserts.
Ask whether the evidence earns the conclusion
Causal arguments often move from a sequence or correlation to a claim that one event produced another. Test for a competing cause, reverse direction, or a changed measurement process. A fact weakens only if it makes the proposed causal explanation less convincing; an irrelevant negative fact does not help.
For samples, compare the surveyed group with the population named in the conclusion. For analogies, ask whether the compared cases share the feature that matters to the result. The best answer addresses the particular link in the argument rather than merely adding a new fact about the topic.
Turn feedback into a repeatable reasoning check
After each question, record the task and the reason your choice failed: conclusion versus premise, missing bridge, scope shift, competing cause, or unsupported comparison. Then write one sentence that states why the credited answer connects to the conclusion. This produces an error record based on reasoning, not just answer letters.
For current-format familiarity and official questions, use LSAC’s LawHub resources. The exercises here are public teaching material, not official questions, an official score conversion, or a guarantee of any result.
Questions about this practice
How do I tell a premise from a conclusion?
A premise gives a reason; a conclusion is what the speaker wants that reason to establish. Rephrase the argument as “conclusion because premise” and check whether the relationship makes sense.
What is the difference between a necessary and sufficient assumption?
A necessary assumption has to be true for the argument to work. A sufficient assumption, when added to the premises, makes the conclusion follow logically.
Does an answer weaken an argument just because it is negative?
No. It must bear on the link from the stated evidence to the conclusion. For a causal claim, a concrete competing cause is often more useful than a general complaint.
Are these official LSAT questions or a score conversion?
No. These are original public teaching exercises. They are separate from official LSAT materials and do not convert performance into an official scaled score.
References
- LSAC Types of LSAT Questions
- LSAC Logical Reasoning Sample Questions
- Khan Academy Necessary Assumptions
- Khan Academy Types of Evidence
- LSAC Official LSAT Practice Tests
Updated October 25, 2026 · PassPredictor