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I'm using the LSAT trainer page 269:

This is supposedly a super-simple example:

Megan has gotten into great shape recently. She must be going to the gym regularly.

Which of the following is an assumption required by the argument?

A) Megan goes to the gym the same number of days each week
B) Going to the gym is one of the best ways to get in shape
C) Everyone who goes to the gym will get in great shape
D) Different people have the same sense o what being in great shape means
E) Megan did not get into great shape solely by doing yoga in her home


Why is E a necessary assumption? If E were assumed, Megan could still do jumping jacks in her kitchen, and that can make "must be going to the gym regularly" invalid. I'm not sure how this assumption negation works... should I just follow this rule even though it doesn't really make sense?

E is the only one which makes going to the gym not be a requirement of getting in shape.

If you could get in shape by doing yoga, then being in good shape would not necessitate going to the gym.

You have to assume E because if she *did* just do yoga at home, then the argument makes no sense. So the argument is necessarily assuming that homa yoga wasn't the sole cause of her fitness.

Your analysis points out why E is not a *sufficient* assumption.

hi thanks for both of your replies.

I think I get it. I have to take "she must be going to the gym regularly" as fact. I think I was just thinking in a different mindset. oops!

jayashae wrote:hi thanks for both of your replies.

I think I get it. I have to take "she must be going to the gym regularly" as fact. I think I was just thinking in a different mindset. oops!

So, for the second part of your OP re: the negation test - it's useful with necessary assumption questions because here, you would negate E to state "Megan DID get into great shape solely by doing yoga in her home." This would destroy the argument because she wouldn't have had to go to the gym regularly to get into shape.

This is a bad question, because E really only weakens it. Both the yoga and the gym can be sufficient for her getting into great shape. You're also presuming there's no gym in her home, and she's not doing yoga in her home gym. Finally, greatness isn't defined. Great can have levels. It's possible yoga could have made her great, and going to the gym daily made her really, really great. E definitely weakens it, but wouldn't totally kill the conclusion.

AReasonableMan wrote:This is a bad question, because E really only weakens it. Both the yoga and the gym can be sufficient for her getting into great shape. You're also presuming there's no gym in her home, and she's not doing yoga in her home gym. Finally, greatness isn't defined. Great can have levels. It's possible yoga could have made her great, and going to the gym daily made her really, really great. E definitely weakens it, but wouldn't totally kill the conclusion.

No, it is a necessary assumption. For these question types if we can negate the assumption and it in turn undermines the argument then it is a necessary assumption (for those who are familiar with logic, consider the modus tollens argument form):

Megan has gotten into great shape recently. She must be going to the gym regularly.

Which of the following is an assumption required by the argument?

E) Megan did not get into great shape solely by doing yoga in her home

(E) Negated - Megan did get into shape SOLELY by doing yoga in her home.

The key word is solely, look at the argument again:

(1) Megan has gotten into great shape recently.
(2) Megan got into shape solely by doing yoga in her home
Therefore - She must be going to the gym regularly.

wat

monadologist wrote:
No, it is a necessary assumption. For these question types if we can negate the assumption and it in turn undermines the argument then it is a necessary assumption (for those who are familiar with logic, consider the modus tollens argument form):

yeah, good analysis. If you think a question is flawed, it's really best to assume you're misunderstanding it and work backward to figure out what you missed.

Edit: just realized this is from a textbook drill, not an LSAT question, so a lower level of deference is probably appropriate. Still think it's fine though.

What if the gym is in her home, and she got into great shape by doing yoga in her home gym? I'm saying an actual LSAT question would take away this possibility. It wouldn't be "the gym", it would be Gold's gym, and E would say her home which does not include Gold's gym.

Reasonable, you can also be sure by checking the other answers. Seeing as how they make no sense, it must be E.

AReasonableMan wrote:What if the gym is in her home, and she got into great shape by doing yoga in her home gym? I'm saying an actual LSAT question would take away this possibility. It wouldn't be "the gym", it would be Gold's gym, and E would say her home which does not include Gold's gym.

"Going to the gym" is inconsistent with "solely doing yoga at one's home", just according to the normal meanings of those phrases. Even if I lift weights, run on a treadmill, etc. all in my home gym, I haven't gone to the gym. The LSAT doesn't use language contrary to its normal meaning.

I mean, to forestall anything further, if you think "I'm going to the gym" would be an accurate, non-misleading statement for doing yoga in your own home gym, then we can just agree to disagree.

Helioze wrote:Reasonable, you can also be sure by checking the other answers. Seeing as how they make no sense, it must be E.

To be fair, he's saying that the question (which is not a real LSAT question, just a drill from a textbook) is not worded well, so it's not an accurate representation of real LSAT necessary assumption questions. So even if the other answer choices are terribly flawed, there could still be a problem with E.