You Can Use Outside Knowledge on the LSAT® (But Only on These Questions)
It's one of the more commonly cited “rules” of LSAT® prep, practically a mantra whispered in study groups and echoed in prep books: "Never, ever use outside knowledge on Logical Reasoning." For years, this has been the ironclad commandment passed down from tutor to student, a warning against bringing your personal experiences, political opinions, or scientific expertise into the sterile, self-contained world of the test. And for good reason—after all, the LSAT® isn't designed to test what you know, but how you think.
But what if this sacrosanct rule is only half the story? What if, by adhering to it too strictly, you're missing a crucial piece of the puzzle? The truth is, while many Logical Reasoning questions are designed to be airtight and insular, there's a significant subset where the LSAT® not only permits outside knowledge but requires it. The key is knowing which questions are which. This post isn't about breaking the rules; it's about understanding them well enough to know when they don't apply. Let's peel back the layers of this common misconception and explore the fascinating distinction between "restrictive" and "innovative" LSAT® questions—a distinction that could be the key to boosting your score.
In sum, while there's a common perception that you can't use any outside knowledge on the LSAT®'s Logical Reasoning section, this isn't entirely true. While you can't use outside information on some question types, there are others where doing so is not only permitted but essential.
Restrictive vs. Innovative Questions
The key is to distinguish between restrictive questions and innovative questions.
Restrictive Questions
Restrictive questions are those where you must base your answer solely on the information provided in the stimulus. The correct answer will be a direct consequence or restatement of the argument presented. For these questions, outside information is irrelevant and can lead you to the wrong answer. Examples of these question types include:
Must be True: The answer must be provable from the stimulus.
Most Strongly Supported: The answer is the most likely inference based on the stimulus.
Main Conclusion: The answer is the argument's primary point.
Argument Part: The answer identifies the role of a specific sentence in the argument.
Method of Reasoning/Parallel Reasoning: The answer describes the logical structure of the argument.
Flaw: The answer identifies a logical error in the argument.
Principle: The answer is a general rule that supports the argument.
Agree/Disagree: The answer identifies the point of contention between two speakers.
For these question types, your goal is to stay within the lines drawn by the test-maker. You're a detective analyzing a single piece of evidence, not a lawyer building a case from scratch.
Innovative Questions
Innovative questions, on the other hand, require you to interact with the argument. The correct answer isn't a simple restatement; it's a new piece of information that affects the argument in a specified way. You're bringing in a new premise or a new piece of evidence to either help or hurt the conclusion. For these questions, you are permitted to use common sense and general, widely known information.
Here are the question types where this applies:
Strengthen: You must find an answer choice that makes the conclusion more likely to be true. This often involves providing a new piece of information that links a premise to the conclusion.
Weaken: You must find an answer choice that makes the conclusion less likely to be true. This can be done by providing information that undermines a premise or provides an alternative explanation.
Sufficient Assumption: You must find a premise that, if true, guarantees the conclusion. This assumption often fills a logical gap in the argument.
Necessary Assumption: You must find a premise that is required for the argument to hold. If this premise were false, the argument would fall apart.
Resolve the Discrepancy: You must find a new piece of information that explains a paradox or a seemingly contradictory situation presented in the stimulus.
Evaluate the Argument: You must find a question that, if answered, would help determine whether the conclusion is valid. The answer to this question often provides crucial information about a potential weakness or strength.
The key to these questions is understanding that the correct answer will likely contain new information that wasn't in the stimulus. This is the only way to strengthen, weaken, or otherwise impact the argument. The LSAT® expects you to use your general knowledge of the world to assess how a new fact would interact with the argument's logic. For instance, if an argument talks about the impact of a new tax on consumer spending, it's reasonable to use your general understanding of economics to evaluate the answer choices.
In conclusion, knowing which questions permit outside knowledge is a crucial step in mastering Logical Reasoning. While restrictive questions demand a hyper-literal reading of the text, innovative questions require you to engage with the argument and its real-world implications. Recognizing this distinction will help you avoid common mistakes and improve your accuracy on test day.