LSAT 117 | Section 4 | Logical Reasoning: Q26

LR Question 26 Explanation

QUESTION TEXT: Political theorist: For all of its members to be strong …

QUESTION TYPE: Sufficient Assumption

CONCLUSION: Not all EU members will be strong in foreign policy.

REASONING:

• For all members of an alliance to be strong in foreign policy, the alliance must respond aggressively to problems.
• An alliance responds aggressively only if every member sees the problems as grave.
• EU countries will all see a problem as grave only if they all agree that it threatens the alliance’s economy.

ANALYSIS: We can draw the reasoning into a chain: All members strong → Aggressive response → All perceive problem as grave → All agree it threatens the economy

But the conclusion is “not strong”.

To prove not strong, we need an answer that tells us one of the required conditions doesn’t happen.

A good way to think about it is: Imagine getting an A requires attending class and going to office hours and doing your homework. If I tell you I didn’t get an A, you can conclude that I didn’t do at least one of those things. Because all of them are required to get an A. So if I didn’t attend class, that’s sufficient to know I didn’t get an A. Same goes if I didn’t go to office hours or if I didn’t do my homework.

It’s the same thing here. The correct answer should negate one of the necessary conditions in the chain (respond aggressively, all perceive as grave, or all agree). Because that would be sufficient to know that they’re not all strong.

Another way to think about it is the contrapositive of our chain.

The contrapositive is:

NOT agree economy → NOT grave problem → NOT respond aggressively → NOT all members strong

The conclusion ends at “not all strong”. Any one of the “NOT”s before it can help us get there.

___________

1. This talks about countries that refuse to join alliances. The argument is only about EU member countries.
2. This introduces wealth and countries becoming less aggressive. None of that appears in the conditional chain.
3. CORRECT. This tells us that the EU countries will not all agree that the problems threaten the economy. If they don’t agree about the economy, then they’re not all strong.
4. We are never told that any EU countries actually fail to perceive the economic relevance of problems. The conditional never gets triggered. A conditional statement by itself does not prove anything unless its trigger occurs.
5. This talks about whether alliances are economically beneficial. The argument is about agreement over whether problems threaten the alliance’s economy, not whether alliances are beneficial.