Q9 - If a child is to develop

[ohthatpatrick]

Question Type:
Match the Flaw (flawed reasoning most parallels the above)

Stimulus Breakdown:
Conclusion: Kids who don't have healthy bones must have insufficient calcium in their diets.
Evidence: In order to have healthy bones, you must have sufficient calcium in your diet.

Answer Anticipation:
Conversationally, we could object to this argument by saying, "Hey, author, maybe more than one thing is required for healthy bones. Maybe regular exercise is also important. Therefore, we can't just look at a kid with unhealthy bones and be sure that she eats insufficient calcium. Maybe she eats plenty of calcium but doesn't get any exercise."

More formally, Match Flaw questions usually pull from the same 5 or so classic flaws, especially Conditional Logic flaws. So if you're reading any sort of flaw question and see conditional language, pay close attention to see whether an illegal reversal or negation is occurring. We are given "healthy bones --> sufficient calcium" and then the conclusion says "~healthy bones --> ~sufficient calcium". So this is an illegal negation. We can look for an "if A, then B" premise and then a "if ~A, then ~B" conclusion.

Correct Answer:
B

Answer Choice Analysis:
(A) This is legit, not flawed. "if firm crust, then right temp" and then "if wrong temp, then not firm crust" (legal contrapositive).

(B) "Taste good --> right amount of flour". Conclusion: "doesn't taste good --> not right amount of flour". Looks good!

(C) The premise is not a conditional, unless you're forcing it. It's just a historical fact. The flaw here is simply in assuming "what has been true in the past must be true again in the future".

(D) The premise is not a conditional, so move on. The conclusion also is not.

(E) Not a conditional premise, unless you're forcing it. "if recipe contest, then more pie than cake". The conclusion would need to say "if it's not a recipe contest, then there are at least as many cakes as pies".

Takeaway/Pattern: This should be straightforward and quick, as Match Flaw questions go. Picking up on the "if" conditional premise is crucial, as it puts us into the mindset of looking for a Conditional Logic flaw. C, D, and E did not have conditional premises, so they are easy to eliminate quickly.

#officialexplanation

[jennifer]

I might be wrong but i translated the question into

HB->C
______________
no HB-> no C

HB=healthy bones C= Calcium

Is the lanuage in answer choice B, the following? I had trouble translating the first sentence of the answer choice. [b] Does "in order" indicate the Necess and must the sufficent?[/b

]TG->F
_______

no TG->no F

I got this question wrong andI am trying to identify what I did. Thanks

[chike_eze]

@Jennifer, I think you got it.

I actually missed this question too because I was going too fast, therefore, I misread the question as "match reasoning" instead of "match flawed reasoning". I then compounded my mistake by incorrectly creating a valid argument -- I'm amazed that the LSAT guys had (A) waiting for me. Incredible!

However, the flawed argument is basically a mistaken sufficient for necessary flaw. Just because developing healthy bones guarantees that the child's diet must have sufficient calcium, does not mean that not having the former necessarily leads to not having the latter.

Healthy Bones --> Sufficient Calcium
Not Healthy bones --> Not Sufficient Calcium (illegal negation)

As you pointed out, (B) Matches this flawed reasoning
Taste good --> Right amount flour
Not Taste good --> Not Right amount flour (illegal negation)

Trivia: If this were a identify the flaw question, the correct answer would probably be "argument is flawed because it mistakes a sufficient for a necessary condition"

[ssfriend.88]

To clarify for myself what you guys did:

I quickly eliminated C, D, E. And came back to A and B

A - Seems to parallel the reasoning, and is set up very similar to our initial argument. However, it seems to be making a sound argument, not a flawed one.

B - Similar structure, but they seem to be subtly changing the format. Reworded in my head to more closely match the stimulus I get:
In order for a cake to taste good, a cake must contain the right amount of flour. It therefore follows that cakes that do not taste good do not contain the right amount of flour.

Ah that makes it much more obvious, B is my choice!

[ManhattanPrepLSAT1]

Text book work you guys! From the bigger perspective of Match the Reasoning/Flaw questions in general, keep in mind that using the structure of the argument can lead to some quick eliminations like answer choices (C), (D), and (E). But once you're down to 2 answers based on similar structure, use the Validity Test. Typically of the two answers that have similar sounding structure, one is a valid argument whereas the other is invalid.

Since the stimulus is a flawed argument so too must be the correct answer choice - thereby eliminating answer choice (A). Just as you guys have worked it through based on the discussion above.

Nice work!

[LisetteP364]

Hi, can you please explain how the stimulus does an illegal negation? Thank you.

[ohthatpatrick]

This was the part of the official explanation that explained it:

We are given "healthy bones --> sufficient calcium"
while the conclusion says "~healthy bones --> ~sufficient calcium".

So this is an illegal negation. We can look for an "if A, then B" premise and then a "if ~A, then ~B" conclusion.

Was there a part of that you didn't understand?