Parallel Reasoning Method
The longest questions on the test. The method makes them routine.
Parallel reasoning questions look intimidating because there is so much to read. The method cuts through the volume.
You do not compare five long arguments at once. You reduce the original to a form, then check each choice against that form. Most choices fail in the first step.
Two tools go with this guide: the miss-pattern analyzer and the blind review worksheet.
Examples on this page are original. They are not real LSAT questions.
The method, step by step
- Abstract the original. Rewrite it with letters: "All A are B. X is B. So X is A." Keep only the logical skeleton.
- Judge it. Is the reasoning valid or flawed? Name the flaw if there is one. Validity must match between the original and the answer.
- Note the conclusion type. Is the conclusion conditional, categorical, or a recommendation? The answer must conclude the same kind of claim.
- Eliminate fast. Abstract each choice one at a time. Drop any choice whose first premise has a different form. Most choices die here.
- Verify the survivor. Lay the full forms side by side. Premises, inference, conclusion, and flaw must all line up.
Worked example: a flawed parallel
Original: "All marathoners train daily. Sam trains daily. So Sam will finish a marathon."
Form: All A are B. X is B. So X is A. This is flawed. Sharing a trait with the group does not make Sam a member.
The match
Answer: "All published authors write daily. Lee writes daily. So Lee will publish a book."
Form: All A are B. X is B. So X is A. Same flaw, same conclusion type, same step order. The topic is irrelevant.
Worked example: a valid parallel
Original: "If the store is open, its lights are on. The lights are off. So the store is closed."
Form: If P then Q. Not Q. So not P. A valid contrapositive.
The match
Answer: "If the dog is hungry, it barks. It is not barking. So it is not hungry."
Form: If P then Q. Not Q. So not P. Valid in both, conditional in both. That is the parallel.
How to get faster
- Eliminate by conclusion type first. It is the quickest filter.
- Then check validity. A valid choice can never match a flawed original.
- Only abstract fully the two or three choices that survive. Do not do full work on all five.
- Beware the topic trap: a choice about the same subject with different logic.
The two-line shorthand
Speed on parallel reasoning comes from compression. For each answer choice, reduce the whole argument to two lines: the evidence in letters, and the conclusion in letters. "All A are B. x is A, so x is B." Write it in the margin. Do the same for the stimulus. Then compare shorthands instead of paragraphs.
This feels like extra work the first five times. After that it becomes the fastest part of the question, because comparing two shorthands takes seconds and comparing two paragraphs takes a minute. The students who finish this question type with time to spare are the ones who stopped reading choices as prose.
Next steps
Practice abstracting short arguments until the letter form feels natural. Speed comes from the abstraction, not from reading faster.
Put it into practice
The free diagnostic scores every question type and shows exactly where you are losing points.