LSAT 2 | Section 2 | Logical Reasoning: Q20

LR Question 20 Explanation

QUESTION TEXT: All savings accounts are interest-bearing accounts…

QUESTION TYPE: Flawed Parallel Reasoning

CONCLUSION: Some savings accounts have tax free interest.

REASONING: All savings accounts are interest bearing, and some interest bearing accounts are tax free.

ANALYSIS: This argument incorrectly draws a conclusion from the necessary condition. There could be many interest bearing accounts that are not savings accounts, such as checking accounts. It may be those accounts that are tax free.

Here is how it looks as a diagram. S ? IB. If I knew that some savings accounts were popular, then I could also conclude that some interest bearing accounts are popular: those that are savings accounts.

You can draw conclusions that use the sufficient condition, since every savings account is interest bearing. You can’t do the reverse, because we don’t know if every interest bearing account is a savings account.

___________

1. This is a good argument. It goes from sufficient to necessary.
2. This is also a good argument. Technically all great photographers are intellectuals, but all includes the possibility of some.
3. CORRECT. This makes the same error. A some statement is made about the necessary condition. This can never lead to a definite conclusion.
4. Also a good argument.
5. This is a good argument. Like B, it could have just as correctly said: “All great photographers must not be intellectuals.”

Recap: The question begins with “All savings accounts are interest-bearing accounts”. It is a Flawed Parallel Reasoning question. Learn more about LSAT Flawed Parallel questions in our guide to LSAT Logical Reasoning question types.