#1- This region’s swimmers generally swim during the day

[swimmergrl101]

I keep getting alot of these types of questions wrong. Are there any tips to help with vulnerable criticism questions?

[Adam Tyson]

Hey there swimmergrl, thanks for asking! When a question stem asks us what makes an argument vulnerable to criticism, it's asking us what is wrong with the argument. We call this a Flaw in the Reasoning question, and your goal is just to describe the flaw.

Understanding the classic types of flaws on the LSAT is key to answering not only these questions, but also weaken questions (where we take advantage of the flaw), strengthen questions (where we try to help fix the flaw), assumption questions (where we identify something important that the author left out, which can be a flaw on their part), Justify the Conclusion questions (where we eliminate the flaw), and many others.

If you happen to have the Logical Reasoning Bible, check out the chapter on Flaw in the Reasoning (Chapter 15 in my 2016 Edition) to get familiar with the many ways that things go wrong in these arguments. You need to know not only how to spot the flaw, but also how the LSAT authors describe them, as that can vary considerably from one type to another. In our full length course materials, you would want to review Lesson 7. In the Accelerated Course, you'll find that discussion about two-thirds of the way into the lesson material (page 117 in my copy). If you don't have any of those, you'll need to find some online resources, including many discussions in this forum, to get a better understanding of those many, many types of flaws.

The flaw in this particular question is one of numbers and percentages (which we cover in more detail in Lesson 9 in the Full Length Course). The author has given us evidence about there being more shark attacks in the day (a numbers claim), and then concludes that swimming in the daytime is not safer than swimming at night (a percentages claim, because it is about the likelihood of being attacked by a shark, and likelihood or probability is about percentages rather than hard numbers). Numbers about subtotals cannot be used to prove percentages unless we also know more about the totals. How many people swam at night, and how many during the day? What percentage of day swimmers vs night swimmers were attacked? That's what we need to know to weigh the relative safety, not just how many were attacked.

This is a common flaw on the LSAT. Two groups are compared, but the size of each group is not given. We learn that one group has more of something, and then a conclusion is made about percentages. But if the groups are of vastly different sizes, those percentages could swing completely in the other direction! Beware of that structure, and that flaw becomes much easier to spot and to describe. Only the correct answer here, E, deals with the problem with the numbers.

Studying those flaws will also help you eliminate wrong answers more quickly and confidently, too. Answer B, for example, describes an ad hominem attack, or source argument, which is when you go after the person that made an argument rather than dealing with the content of their argument. That's not what happened here, so if you know what that answer is describing it should be easy to eliminate just because we know what it is saying and that it didn't occur in the stimulus.

Check out those resources and study your flaws! That should lead to major improvement on a wide variety of questions.

Good luck, keep at it!

[swimmergrl101]

Thank you so much for your response! Do you recommend any online resources?

[Adam Tyson]

This one, of course, as well as our blog. Also check out our self-study area on our website at http://students.powerscore.com/self-study/

As far as finding online discussions of what all the flaw types are, I don't have one to point you to, but you can certainly run a web search on "LSAT Flaws". Just be careful about what you find - not all sources are as well researched and analyzed as what we provide. Of course I highly recommend our books, which are some of the best sellers in the industry!

Good luck with your continued studies! Let us know how else we can help you along the way.

[blade21cn]

I got this question wrong by choosing (A). The premise only establishes that daytime shark attacks are also possible, but that does not get to the conclusion that swimming during the day versus at night are equally dangerous, or the other way around (swimming during the day is actually more dangerous). The author fails to consider certain possibilities that could still make night swimming inherently dangerous, which is what (A) is pointing out.

I eliminated (E) because it requires the condition that "more people swam at night," and thought regardless whether people swam in shark-infected water or not, it is still dangerous. Now, I can see the hypothetical "danger" equals to its realization that "if you swim in it you will be attacked." So I think this question is about (E) being a stronger weakener than (A), which also weakens. However, the common consensus is that only one answer choice is correct/weakens and it should not be a judgment of degree. Thus, can any expert shed some light on why (A) is not a weakener at all? Thanks!

[Adam Tyson]

In my view, blade21cn, answer A does nothing to weaken the argument. A good Flaw answer must have two characteristics: 1) it must be true, and 2) it must be a problem for the argument. While answer A might be true - the author never did mention anything about nocturnal sharks - it's not a problem, because the author would respond with "sure, some might be nocturnal, but nonetheless most attacks happen during the day, so it's still not more dangerous at night."

Ask yourself WHY answer A might weaken the argument. Isn't it because the prospect of more people swimming at night, while those sharks are hunting, might mean the number of shark attacks at night could increase? In other words, answer A can hurt the argument only because answer E hurts the argument! That's another proof that E is the better answer: answer E is a problem whether A is true or not, but A is not a problem unless E is a problem. We sometimes call that the Uniqueness Principle of answer choices - if one answer forces another answer to also be correct, the one doing the forcing cannot be the right answer. Answer A forces answer E to be correct, so answer A fails that test.