PrepTest 127

Incorrect. First off, this answer, if anything, suggests that farm-raised mussels might not be sand-free, hurting the argument. Second, cornmeal isn't established as being the only way to remove sand from mussels—maybe they can be raised in water without sand to begin with.

Incorrect. This answer is trying to get you to think that the first step might still be necessary if sand isn't the only contaminant that needs to be removed. However, if these contaminants exist, there's no indication that cornmeal would be effective at removing them from mussels, so this answer isn't necessary for the argument that the Chef can skip the first step to hold.

Incorrect. First, the argument specifically states that the cornmeal is added to remove sand, not to influence taste. Second, even if it does affect the taste, it could make it worse (but still better than eating sand), which would argue in favor of the conclusion, so it doesn't kill the argument to negate this answer. It's therefore not necessary for the conclusion to hold.

Incorrect. The recipe could have been written by someone who didn't know about sand-free, farm-raised mussels, or who presumed Chef's wouldn't use them, or for any other reasons despite being written after farm-raised mussels became available.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Mussel recipe step #1 - Sprinkle live mussels with cornmeal to remove sand.
Chef - Mussels from seafood markets are from farms, so they don't contain sand, so I can skip step #1.

Answer Anticipation:
There are some questions on the LSAT where the assumption is "hidden in plain sight." What we mean by that is that what's missing from the argument seems so basic that it's easy to miss it.

The argument here starts by explaining why cornmeal is sprinkled on live mussels in this recipe—it's not to make them taste better, or retain their juices, but to clean the sand out of them.

From that, the Chef concludes that she can skip that step. Why? Because mussels from seafood markets are farm raised, so they don't have sand. No sand, no need to clean them out using cornmeal. Seems valid, right?

Digging in deeper, let's start with the conclusion—the Chef can skip the step meant to clean sand out of the mussels. What would allow her to skip that step? If the mussels didn't contain sand. Doesn't it establish that? Nope—it establishes that farm-raised mussels/mussels purchased at seafood markets don't have sand in them. She never establishes that she got the mussels she's cooking from a seafood market.

See what we mean by an assumption hiding in plain sight? These can be really hard to spot, so it's important that you have multiple lines of attack when dealing with a question. And we used one here—clearly defining what would need to be established in the premises to justify the conclusion. From there, you can be a lot more precise in analyzing the premises to see where the gap is.

Answer Explanation:
This answer reflects the necessary assumption of the argument—that the Chef got her mussels from the seafood market (and thus they were farm-raised and sand free). If she didn't get them from a seafood market, then there's no guarantee they don't have sand, and the first step can't be skipped.

Key Takeaway:
When you're failing to see the assumption in an argument, one way you can try to figure it out is to look at the conclusion and figure out what would need to be true to justify it. From there, you can compare the actual premises to that and see where it falls short.