LSAT and Law School Admissions Forum

Get expert LSAT preparation and law school admissions advice from PowerScore Test Preparation.

 Administrator
PowerScore Staff
  • PowerScore Staff
  • Posts: 8219
  • Joined: Feb 02, 2011
|
#22836
Complete Question Explanation

Must Be True—SN. The correct answer choice is (D)

This stimulus presents several conditional statements regarding a certain store's policy concerning sales:

At all times there is either a managers sale, or a holiday sale, or both:
  • no manager's sale → holiday sale

    no holiday sale → manager sale
If a manager wishes to clear out a line of merchandise, they have a manager's sale:
  • manager wishes to clear → manager's sale
If a holiday falls within a given month and there is excess merchandise, they have a holiday sale:
  • holiday

    and .......... holiday sale

    excess
In August, there is no holiday and no excess:
  • ..... ..... ..... no holiday

    August .......... and

    ..... ..... ..... no excess
The question stem is a Must Be True, so the right answer choice should be confirmed by the conditional statements above.

Answer choice (A): This answer choice is not supported by the passage; all we can say is that if there is excess in any holiday month, there will be a holiday sale. If there is no excess, we have no information on what the store will do.

Answer choice (B): This incorrect answer choice is unsupported by the stimulus, as there may be other months without holidays, and other holiday months without excess.

Answer choice (C): We know that this is unsupported; there could still be excess merchandise, and there could still be a concurrent holiday sale as well.

Answer choice (D): This is the correct answer choice, confirmed by the first conditional rule presented in the stimulus: there is always either a managers sale, or a holiday sale, or both.

Answer choice (E): This is a mistaken negation of a portion of the final conditional rule. According to the stimulus, if it is August there is no excess: ..... August → no excess

This choice incorrectly asserts a mistaken reversal: ..... no excess → August
 rameday
  • Posts: 93
  • Joined: May 07, 2014
|
#15394
How would I diagram this? At all times there is either a managers sale or a holiday sale or both going on?

MS :dblline: HS I know this means one or the other but not both.

A
 Jon Denning
PowerScore Staff
  • PowerScore Staff
  • Posts: 882
  • Joined: Apr 11, 2011
|
#15398
Hey rameday,

You're close! The fact that at least one must always be occurring means that they can't both be absent, hence we'd show it as follows:

..... MS :dblline: HS

What that means is that if one is not present/happening, the other must be. By default this also allows the possibility of them happening simultaneously...it merely rules out the option of them both being removed.

Hope that helps!
 hoyasaxa21
  • Posts: 5
  • Joined: Jul 16, 2020
|
#77689
Good afternoon,

Does answer choice (E) assert a mistaken negation or a mistaken reversal of a portion of the final conditional rule?

Thank you very much, and have a great day!

Chris
 Paul Marsh
PowerScore Staff
  • PowerScore Staff
  • Posts: 290
  • Joined: Oct 15, 2019
|
#78391
Hi hoyasaxa! You're exactly right - Answer Choice (E) contains a Mistaken Reversal of the last sentence of the stimulus. That portion of the stimulus tells us, in August there is never excess merchandise.
August :arrow: no excess merchandise
(E) Mistakenly Reverses that to say:
No excess merchandise :arrow: August

So we can safely toss out (E), since it's a Mistaken Reversal.

Now, it seems like from your question you're wondering if this is also a Mistaken Negation. The answer is yes - Mistaken Reversals and Mistaken Negations are actually the same thing! Watch this. Let's say we have the conditional "If A, then B". We diagram that as:
A :arrow: B
A Mistaken Reversal of our conditional would be:
B :arrow: A
And a Mistaken Negation of our conditional would be:
NOT A :arrow: NOT B

But let's return to our Mistaken Reversal. B :arrow: A. What if we take the contrapositive of that Mistaken Reversal, what would that look like? Well it would be:
NOT A :arrow: NOT B

But wait a minute, that's the exact same as our Mistaken Negation! That's because Mistaken Reversals and Mistaken Negations are actually logically equivalent to each other. Remember that the contrapositive of a conditional is logically equivalent to that conditional. A Mistaken Reversal and a Mistaken Negation are just contrapositives of each other. They're the exact same Flaw - mistakenly confusing the sufficient and necessary conditions of a conditional. So don't get ever get hung up on "Oh is this a Mistaken Negation or a Mistaken Reversal?" It doesn't matter, because they're the same thing! An LSAT question will never ask you to differentiate between those two because (and I'm sorry to sound like a broken record here) they're logically identical! All you need to recognize is that an argument messed up by confusing the sufficient and necessary conditions.

Hope that helps!

Get the most out of your LSAT Prep Plus subscription.

Analyze and track your performance with our Testing and Analytics Package.