Parallel Reasoning Questions
Ignore the topic. Match the logic.
Two tools pair with this method. The miss-pattern analyzer shows which question types cost you the most points, and the blind review worksheet gives you a second pass at every miss.
What the question asks
The question asks which argument has the same reasoning structure. The stem says something like "Which one of the following arguments is most similar in its reasoning?"
You match the logic, not the topic. A parallel argument about farming can match an original about finance if the structure is the same.
Step-by-step method
- Abstract the form. Rewrite the argument with letters. Example: "All A are B. X is A. So X is B." Strip away every detail that is not doing logical work.
- Note valid or flawed. Decide whether the reasoning works or breaks, and name the flaw if it breaks. A valid argument can never parallel a flawed one.
- Compare choice by choice. Abstract each choice the same way and lay the forms side by side. Every step must line up: premises, conclusion type, and flaw.
- Check the conclusion. The conclusion type must match. A conditional conclusion needs a conditional match. A categorical conclusion needs a categorical match.
- Ignore the topic completely. A choice about the same subject with different logic is the classic trap. Topic similarity means nothing.
Worked examples
Both examples are original. They are not real LSAT questions.
Example 1
All marathoners train daily. Sam trains daily. So Sam will finish a marathon.
Which one of the following is most similar in its reasoning?
The answer: All published authors write daily. Lee writes daily. So Lee will publish a book.
Why: Both argue: all A are B; X is B; so X is A. Both commit the same error of treating a shared trait as proof of membership. The topic changed. The form did not.
Example 2
If the store is open, its lights are on. The lights are off. So the store is closed.
Which one of the following arguments exhibits the same pattern of reasoning?
The answer: If the dog is hungry, it barks. It is not barking. So it is not hungry.
Why: Both are: if P then Q; not Q; so not P. Each is a valid contrapositive. The structure matches at every step.
Match the conclusion first
The fastest filter on parallel reasoning is the conclusion. Read the original argument, note what kind of conclusion it reaches: a prediction, a recommendation, a causal claim, a value judgment. Then cross out every answer choice whose conclusion is a different kind. This usually removes two or three choices in seconds.
Next, match the evidence and the move, in that order. The parallel argument must reason the same way: same structure of premises, same kind of inference, same flaw if the original is flawed. Validity must match too. A valid argument can never be parallel to an invalid one, no matter how similar the topic sounds.
The classic trap is the topic match: a choice about the same subject with a different skeleton. The test writers know you read for content. They build one choice that feels familiar and gets the structure wrong. Strip the topic out of every choice, down to letters and arrows, and compare the skeletons. Familiar is not parallel.
Common traps
- Same topic, different structure. Familiar subject matter is the bait.
- Same conclusion, different path. The ending can match while the reasoning differs.
- A valid argument offered as parallel to a flawed one, or the reverse. Validity must match.
- A choice that matches the first premise but diverges at the conclusion.
Practice the method
The free diagnostic scores every LR question type and shows exactly where you are losing points.