LSAT Principle questions: matching a rule to a case

A principle is a general rule about what ought to happen, or what counts as what. Principle questions ask you to move between that rule and a specific case. They are among the most common questions in the section, and they are unusual in that the same label covers two jobs that require opposite motions.

The two directions

In the first, the passage states a principle and the answers are cases. The stem reads something like "which one of the following judgments most closely conforms to the principle above". You hold the rule fixed and test each case against it.

In the second, the passage states a case and a judgment about it, and the answers are principles. The stem reads "which one of the following principles, if valid, most helps to justify the reasoning above". Now the case is fixed and you are shopping for a rule that licenses the conclusion someone already drew. This direction behaves far more like a Sufficient Assumption question than like anything else, and treating it that way is the single biggest improvement most students make on the type.

The conditional underneath

Nearly every principle can be written as a conditional: when these conditions hold, this follows. "A reviewer should disclose any payment from a company whose product they assess." Conditions: you are a reviewer, and you took payment from such a company. Consequence: disclose.

Once it is in that shape, matching becomes mechanical. The facts of the case have to satisfy every condition on the left, and the judgment has to be exactly what the right side licenses. Both halves are load-bearing, and the wrong answers are built by breaking one of them while leaving the other intact.

How the near misses are built

• A condition goes unmet. The case involves a reviewer who was offered payment and refused it. The rule never triggers, so it licenses nothing — and the answer still sounds like the rule, because every word of the rule is in it.
• The consequence is stretched. The rule says disclose; the judgment says the review should be retracted and the reviewer barred. Retraction may be reasonable, but the stated rule does not get you there.
• The conditional runs backwards. The rule says payment requires disclosure; the answer treats disclosure as proof there was payment. This is the necessary-and-sufficient confusion wearing a different hat, and it is worth recognizing as the same error you already know from Flaw questions.
• The principle is broader than the case needs. In the justify direction, a rule that covers the case but also commits you to a great deal more is usually still correct — breadth is not a defect there. In the conform direction it often is. Which way the question runs decides whether breadth is a problem.
• Right topic, wrong force. "Should", "may", "must" and "is never justified in" are not interchangeable. An answer that permits what the rule requires has changed the rule.

A habit that helps

Before reading the answers, say the rule as an if-then in your own words, and say which direction the question runs. Two sentences, ten seconds. Students who skip this step tend to pick the answer that shares the most vocabulary with the passage, which is precisely how the near misses above are engineered to win.

Then check the case against the conditions one at a time. If a condition is unmet, the answer is out no matter how well it reads, and no amount of thematic fit rescues it.