Q11 - Inspector: The only fingerprints on the premises are t

[samantha.rose.shulman]

PT65, S1, Q11 (Match The Flaw)

(A) is correct.

This is a Match the Flaw question. Remember your process! It is critical we find the flaw before looking at the answer choices. The argument core is as follows:

Only Fingerprints On The Premise Are Mr. Tannisch’s -> Whoever Has Missing Diamonds Must Have Worn Gloves

By concluding that whoever has the missing diamonds must have worn gloves, what is this argument assuming? It is assuming that Mr. Tannisch does not have the diamonds!

Upon reading this stimulus, you might find yourself asking, "How does the author know it wasn’t Mr. Tannish? Doesn’t all of the evidence point to him? " These are very good questions. How does the author know? She doesn’t! Or at least she does not provide us with any information to support this conclusion. This is the flaw. The author has not considered a very apparent alternative possibility (that it was Mr. Tannish).

Now that we have identified the flaw, let’s find the answer choice that makes the same error. These questions can be incredibly time consuming, and they are meant to be. Eliminating answer choices first based on their conclusions is an effective strategy that can save you a lot time and confusion.

Note that the conclusion in our original argument is very definite: "whoever now has his guest’s missing diamonds must have worn gloves". We can eliminate (B), (C), and (E) because they do not match the "must". (B) uses the word "might" in its conclusion, (C) uses the word "unlikely" in its conclusion, and (E) is conditional and uses the word "probably" in its conclusion.

Now we are left with (A) and (D).

(D) is incorrect. Although it is not a perfect argument, the logic isn’t obviously flawed. This answer choice would be more tempting if it read, "All of Marjorie’s cavities are on the left side of her mouth. Hence, she must chew more on the right side than on the left".

(A) makes the exact opposite conclusion we expect it to make (like our stimulus!). How do they know it is not the food that made the campers ill? Doesn’t all of the evidence point to it being the food? Do these questions sound familiar? We asked ourselves very similar questions when reading the original stimulus!

Also note that this answer choice, similar to our stimulus, has made a big assumption in order to reach its conclusion. The conclusion is that the cause of the illness must not have been something they ate. The assumption is that it wasn't the Big Lake Camp cafeteria food.

[shirando21]

do we always have to match "Must" in answer choices?

I was looking at flaw type.

C is more like a temporal flaw, it is not necessarily true what usually happens will happen in the future. The argument is not a flaw of this type.

D is kind of correlation and causation. The argument is not of this flaw type.

E is ineffective analogous. The argument is not of this type.

B just reads as non-sense to me.

Can I use my method to solve this problem? or the "must" test will always guarantee distinguishing the right answer from the wrong answers?

[srk827]

I would like to know this as well. For matching questions, do the conclusions always need to match?

[missbenyamin]

do we always have to match "Must" in answer choices?

I was looking at flaw type.

C is more like a temporal flaw, it is not necessarily true what usually happens will happen in the future. The argument is not a flaw of this type.

D is kind of correlation and causation. The argument is not of this flaw type.

E is ineffective analogous. The argument is not of this type.

B just reads as non-sense to me.

Can I use my method to solve this problem? or the "must" test will always guarantee distinguishing the right answer from the wrong answers?

Yes, it's important for the conclusions to match in degree - i.e. if the original conclusion says must, the correct answer choice will have a conclusion that is equally as strong (as opposed to a weaker answer, such as "likely," or "probably")

While having the conclusions match in degree is not the most important aspect to look for (it is a "match the flaw" question after all,) answers that have a mismatch in degree are wrong and can be much more easily eliminated (v. identifying mismatch in flaw) and this method can thus be a very efficient approach to eliminating answers for "match the flaw" questions.

Hope that helps.

[Noah.hunter]

For whatever it is worth, I am an LSAT tutor and scored 178 and I think this question is seriously flawed. Sure, you can defend answer A with legitimate reasoning, but I think there are too many problems with the question to deem it fair:

1) The logical error could easily be defined as "assuming a thing to be true without sufficiently ruling out other possibilities." If so, then D assumes a fact without ruling out other possible causes while A assumes something to not be true when it could be true.

2) The fact pattern itself is just muddy. The diamonds could be misplaced. If there are guests why are their finger prints not present even if they are not the thief? The thief could have wiped down finger prints or somehow not left them even if not gloved. Someone could have cleaned and on and on.

3) Essentially, there are too many flaws with this reasoning to settle on a parallel type of flawed reasoning.

If you missed this question but chose D, I think there is very little to learn from this question. Answer A may be more right than D, but not in a way that is sufficiently legitimate in my opinion to rule the question fair.

[tommywallach]

I agree. This question is one of the rare very ones I would call ridiculous. For me, the error in the original stimulus is not seeing other paths away from the conclusion (as you said, the person could've wiped away their fingerprints, or not touched anything other than the diamonds). (D) does the same thing. This question is uselessly stupid.

-t

[vickpetrosian1]

YES AGREED WITH THE TWO INSTRUCTORS ABOVE ME THIS IS A FLAWWWWWWWED QUESTION...... I answered D because of the automatic assumption in the question that chewing on a certain side causes cavities that is incorrect my pops is a dentist trust me.... Cavities are caused by genetics not by foods or chewing.... got off track but the assumption is clear in that the author assumes" the person chews more on the side of the cavities rather than the other side... just like in the main argument the author assumes " Mr Tannisch could not have stolen it himself but must be someone else and that someone else was wearing gloves....

LSAC please think before you put these questions out here... unless this is your way of curving the edge...