Logical Reasoning
Logical Reasoning supplies the majority of scored points on the current LSAT: several timed sections of short stimuli, each followed by a single question. No outside knowledge is required, but everything inside the passage matters. The section tests whether you can separate a conclusion from its support, name the unstated premise connecting them, and predict what would strengthen, weaken, or destroy the argument.
Find the conclusion first
Conclusion indicators ("therefore," "clearly," "the argument concludes") help, but the reliable test is: which claim is the rest of the stimulus trying to establish? Everything else is a premise. A stimulus with no conclusion signals an inference or Must Be True question, where the credited answer is provable from the facts, not merely compatible with them.
Necessary versus sufficient
A sufficient assumption, added to the evidence, makes the conclusion follow outright, often as a conditional bridge: "If the plant is a legume, it fixes nitrogen." A necessary assumption is one the argument cannot survive without; test it by negating the answer. If the negation destroys the reasoning, the statement was necessary. Necessary assumptions are often weak and negative ("the sample was not drawn from a single neighborhood"), so do not reject an answer for sounding modest.
Worked example
"Everyone who passed the bar is licensed to practice law. Okafor is licensed. Therefore, Okafor passed the bar." Formalized as passed → licensed, the premise affirms the necessary condition while the conclusion asserts the sufficient one. That is the converse error; the credited Flaw answer says the argument treats a condition necessary for passing as sufficient. No added premise repairs the inference, so this stimulus could not support a Sufficient Assumption question.
Traps that cost marks
- Term shift: evidence about "reported crime" cannot support a claim about crime.
- Percentages versus numbers: a larger share of a smaller group is fewer people.
- Correlation treated as causation, with no third cause or reverse direction considered.
- Extreme wording ("only," "never," "all") needs support in a credited answer.
- Self-selected survey samples generalized to whole populations.
- Missing the stem: check "EXCEPT" and "if true" before evaluating.