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PT 58 had a couple of tough JTC questions that I'm hoping someone could help me dissect/diagram. They are Section 1, Q25 and Section 4, Q24.

Thanks!

LSAT Blog wrote:These are one of the few question-types I often diagram.

What you're describing is the most common format for these types of questions, but not the only format. The correct answer to a Sufficient Assumption (Justify) question is often simply a restatement or the contrapositive.

I'm going over the most common format with formal logic, then with a few examples from real PT questions:

Evidence: A ---> B
Conclusion: C ---> B

Sufficient Assumption #1: C ---> A
Sufficient Assumption #2: NOT A ---> NOT C

Contrapositively...

Evidence: D ---> E
Conclusion: D ---> F

Sufficient Assumption #1: E ---> F
Sufficient Assumption #2: NOT F ---> NOT E

Thanks to Steve's JTC example from another thread, I was able to solve S1, Q25. It seemed really complex to get through, and I'm not sure if I would be able to do this under timed conditions, so if someone has an easier method than the one I outline below, please share!

PT 58, S1, Q25

If a wig has any handmade components, it is more expensive than one with none. Similarly, a made-to-measure wig ranges from medium-priced to expensive. Handmade foundations are never found on wigs that do not use human hair. Furthermore, any wig that contains human hair should be dry-cleaned. So all made-to-measure wigs should be dry-cleaned.

P1: Wigs with handmade components --> More expensive than non-handmade
P2: Made-to-measure wigs --> Medium-priced to expensive.
P3: Handmade components --> Wigs with human hair.
P4: Wigs with human hair --> Dry-cleaned
Conclusion: Made-to-measure wigs --> Dry-cleaned

Sufficient Assumption: Made-to-measure wigs --> Wigs with human hair

Correct Answer Choice (A): Any wig whose price falls in the medium-priced to expensive range has a handmade foundation. (Medium-priced to expensive --> Handmade components, which is the SAME as Made-to-measure wigs --> Wigs with human hair)

Answer choice (B): If a wig's foundation is handmade, then it is more expensive than one whose foundation is not handmade. (This is a restatement of P1, so it's wrong.)

Answer choice (C): A wig that has any handmade components should be dry-cleaned. (This is a combination of P3 and P4 and includes a common element from the conclusion, so it's wrong.)

Answer choice (D): If a wig's foundation is handmade, then its price is at least in the medium range. (Wrong. Made-to-measure wigs are in medium to expensive range.)

Answer choice (E): Any wig that should be dry-cleaned has a foundation that is handmade. (Wrong because it's a Mistaken Reversal of P3 and P4.)

PT 58, Section 4, Q24

Using the model below (thanks Steve!), I solved this question as well. Any takers on an easier method? This one was also very complicated.

Evidence: D ---> E
Conclusion: D ---> F

Sufficient Assumption #1: E ---> F

The genuine creative genius is someone who is dissatisfied with merely habitual assent to widely held beliefs; thus, these rare innovators tend to anger the majority. Those who are dissatisfied with merely habitual assent to widely held beliefs tend to seek out controversy and controversy seekers enjoy demonstrating the falsehood of popular viewpoints.

P1: Dissatisfied with habitual assent --> Genuine creative genius
P2: Genuine creative genius --> seeks out controversy
P3: Seeks out controversy --> Enjoy demonstrating falsehood.
Conclusion (bolded): Genuine creative genius --> Rare innovators --> Anger majority

Sufficient Assumption: Enjoy demonstrating falsehood --> Anger majority

Answer choice (A): People become angry when they are dissatisfied with merely habitual assent to widely held beliefs. (Out of scope as "Angry" is not in the stimulus. We're not talking about people who become angry with geniuses, but how geniuses anger the majority.)

Correct Answer choice (B): People who enjoy demonstrating the falsehood of popular viewpoints anger the majority. (Enjoy demonstrating falsehood --> Anger majority.)

Answer choice (C): People tend to get angry with individuals who hold beliefs not held by a majority of people. (Wayyy out of scope, and like A, we're not talking about people who become angry with geniuses.)

Answer choice (D): People who anger the majority enjoy demonstrating the falsehood of popular viewpoints. (Anger majority --> Enjoy demonstrating falsehood. This is a Mistaken Reversal of the sufficient assumption.)

Answer choice (E): People who anger the majority are dissatisified with merely habitual assent to widely held beliefs. (Anger majority --> Dissatisfied with habitual assent. This is a Mistaken Reversal of P1 and Conclusion, so it's wrong.)