#2 - Psychologist: A study of 436 university students found

[SLF]

Both answer choice B and D seem to be correct answers to me. How do I determine which one is "most" correct?

[Steve Stein]

Hi,

Thanks for your question. This question presents a causal argument, and correct answer choice (D) describes the issue with this argument: the author concludes that napping leads to insomnia, without considering the possibility that insomnia is actually the cause, and napping the effect. Answer choice (B), on the other hand, goes too far: the author of the stimulus does not assert, or presume, the very broad claim that all types of insomnia have the same cause--the stimulus' conclusion is limited to the assertion that napping is one cause of insomnia.

I hope that's helpful! Please let me know whether this is clear--thanks!

~Steve

[SLF]

Hi Steve,

I understand the difference now. The conclusion's words "very likely" and "tends" do not match with "all".

Thanks so much for your reply.

[cinnamonpeeler]

Just some confusion as to why (B) is wrong. I did pick (D) because I thought it is the biggest flaw that the argument commits. However, when LSAT speakers make a causal argument, don't they assume that there is only one cause for that one effect? So if a speaker asserts that napping causes insomnia, doesn't she think that napping is the only thing that causes insomnia, and that napping always causes insomnia? Thus, insomnia is always caused by napping. Why is (B) wrong then?

[Jeremy Press]

Hi cinnamonpeeler,

Whether or not that assumption is being made depends on the language of the conclusion. Here, the conclusion waters down the causal relationship, indicating that the author has not assumed napping is the only cause. The author says that it is "very likely that napping tends to cause insomnia." Since it's only "very likely," the author admits there's a possibility something else could be involved. Since napping only "tends to" cause insomnia (rather than saying "napping causes insomnia," without qualification), the author admits there could be other factors involved in some cases of insomnia.

Watch the language of the conclusion. The Logical Reasoning Bible will tell you that the assumption you're thinking of is being made when the author asserts (without qualification) a sole cause. If the conclusion is, "napping causes insomnia," then that assumption is being made. With the kinds of likelihood and tendency qualifiers you see here, that assumption is not being made.

I hope this helps!

Jeremy