In this chapter we’re going to teach formal logical to better answer inference questions.
CHALLENGE: Identify Inferences
The LSAT tests formal logic through Must Be True questions. They’re identifiable through their distinctive question stems:
- Which of the following must be false?
- Which of the following is most strongly supported?
- If the statements above are true, which of the following must also be true?
- Which of the following may be correctly inferred?
- Which of the following inferences (inference means the same thing as “must be true” on the test) is best supported by the statement made above?
(Conclusions differ from inferences in that conclusions are the result of premises and inferences must be true if the premises are true).
How to solve
- Diagram out the statements of the argument (if you can’t get a quick grasp of it in your head).
- Make valid inferences from these statements (transitive property and contrapositive). Note any false inferences, if any, such as the Fallacy of the Converse and Fallacy of the Inverse. To understand these concepts, we’ll be deep diving into formal logic in this chapter.
- In Must be True questions you’ll find four choices that can sometimes be wrong and one that can never be wrong (that’s the correct choice!). Go through every answer choice systematically and check if it is ALWAYS true. These questions should always be tackled using PoE (process of elimination) method. If you can find a reasonable situation when it is not always true, eliminate it. Gradually eliminate answer choices until you have one left.