You’re several minutes into the logical reasoning section and on question five. It’s a necessary assumption question. Great! You know how to do those. You read the argument and boil the core down to:

Premise: Richie hates snails.

Conclusion: Richie will stomp on that snail over there.

You are relieved to spot the assumption immediately: If Richie hates something, he will stomp on it.

Reading through the answer choices, you look for one that matches. You get rid of C, D, and E easily. A and B remain, and they both look pretty good because they’re both about stomping and hating snails. Luckily, you know what to do at this point: Negate each answer to see what happens. If negating (making it untrue) wrecks the argument, that means it’s necessary, i.e. your answer!

But wait. B reads, “If Richie hates something, sometimes he kills it.”

You’re at a loss on how to negate that. Do you say, if Richie doesn’t kill something, he doesn’t hate it? Or if he doesn’t hate it, he’ll kill it? Or if he does hate it, he won’t kill it? How do you negate an “if” statement?

To negate a conditional, negate the necessary clause. Leave the conditional clause (the “if” clause) alone. In this case the correct negation would be the third one above: If Richie hates something, he won’t sometimes kill it (or he’ll never kill it, same thing).

What happens to our argument when we put it that way? Destroyed! Answer choice B is correct.

Come back to the blog next week for Part II of Advanced Negation Techniques.

No, that’s not an order, but it is a great idea. Here’s the problem; there’s a limit to how many tests you can work through without completely tuning out and not getting anything out of it. The good news is you can study the LSAT everyday while minimizing your exposure to the actual test.

Quick disclaimer: this is NOT a recommendation to ditch practice tests or strategies. This is a way to supplement your test studying so you are always in LSAT mode.

That said, consider what the LSAT is actually testing. It is a test that evaluates your ability to think logically. You are presented with chances to think logically all the time (though if you’re like me, you may not always live up to the potential). If you identify and use those opportunities, they become excellent chances to study.

Start with reading comprehension. Whether you’re in school or at work, you have to read, probably pretty often. We read for content – to find out what the article is saying. Start reading for perspective as well. As you go through your books and articles, ask yourself these questions: Read more

Across the board on logical reasoning questions, it’s important to know what kind of argument you’re dealing with:

(1) What is it arguing?

(2) How does it go about it?

(3) Is there a problem with it?

When it comes to (1), it’s often not enough simply to identify the conclusion of the argument and note its substantive components. You should get into the habit of characterizing the conclusion in terms of precisely what its arguing, and to do that, you should always look around the verb–that is, to the action of the sentence.

I took a moment to write down the categories that I personally put conclusions into in my head as I read. This isn’t an exhaustive list of conclusion types or one that I’m suggesting you apply as gospel, but it’s an example of how you might characterize conclusions for yourself as you read:

Judgmental conclusions: These are conclusions that, yep, cast some kind of judgment. They usually contain words like “should” (or “should not“), or justifies/is justified (or doesn’t).

Statements of fact: These are conclusions that state facts. Something is/are true, will happen, do/does occur, shall occur. (Notice that I don’t separate between “is” in the present and “will” in the future since both still say what is true.)

Likelihood: Distinct from the previous category, these conclusions don’t argue that something definitely will or does happen but that it might, and they sometimes give a likelihood. They include words like “might,” “may,” “could,” “probably,” and “likely” or “unlikely.”

Comparative: You guessed it–these are conclusions that X is no worse than Y; X is better than Y; X is more likely to happen than Y. On these, they key thing to remember is to note exactly how the two components are being compared; X “is no less bad” than Y is not the same as saying that X is better than Y. (Can you think of why? It’s because if X is no less bad than Y, X and Y could still be equally bad.)

Pulitzer Prize-winning playwright David Mamet’s recent gun control rant in Newsweek drew ample criticism for making no sense whatsoever, disappointing some (including me) who like his plays. It’s an illogical essay–not illogical by nerdy LSAT standards, but nonsensical by pretty much everyone’s real world standards, regardless of your views on gun control. (Read his paragraph on arming criminals so they’ll accidentally shoot themselves–then read it again, and again.) So it’s not really fair that I’m about to shred his logic–in the sense that it’s kicking a guy when he’s down, or a sick puppy. But as it’s a puppy with several Tony and Oscar nominations who is apparently packing heat, I think he’s fine.

Find the flaws in these arguments of Mamet’s.

1. “As rules by the Government are one-size-fits-all, any governmental determination of an individual’s abilities must be based on a bureaucratic assessment of the lowest possible denominator.”

Core: One size fits all → Lowest possible denominator

Flaw: This argument expects we have any idea what a “one size fits all” rule is and what a “lowest common denominator” person is, but as we do in logical reasoning, let’s accept these terms on their face. What’s being assumed?

The gap that jumps out to me is the assumption that something made to fit everyone is going to be something tailored to the person at the extreme end. But think about what “one size fits all” actually means–not XXXXL, because that’s not “fitting.” Those OSFA tags you only see, in fact, on average sizes. Think about trying on a hat in a store, or a pair of gloves, or a t-shirt. It’s not a great fit for most of us. It’s not a horrible fit for most of us. It’s designed to fit the average person. If “one size fits all” actually meant the smallest person or largest person, it would in fact fit very few of us.

2. “Violence by firearms is most prevalent in big cities with the strictest gun laws. Cities of similar size in Texas, Florida, Arizona, and elsewhere, which leave the citizen the right to keep and bear arms, guaranteed in the Constitution, typically are much safer. More legal guns equal less crime.”

Core: Cities with stricter laws have more violence + cities with less stringent laws have less → More legal guns equals less crime

Flaw: Makin’ it easy for us, Mamet! Just because everyone with big feet is smarter than everyone with little feet doesn’t mean that big feet make you smarter. It means we’re adults and educated; five-year-olds are still eating glue and pooping in their pants. In this particular argument of Mamet’s (which may also be flawed empirically, but again we’re concerned with his logic), reverse causation could very well be in play. Maybe the cities with more violence have stricter laws because they are more violent and need them?

3. “Will increased cosmetic measures make anyone safer? They, like all efforts at disarmament, will put the citizenry more at risk. Disarmament rests on the assumption that all people are good and basically want the same things.”

Core: Disarmament rests on the assumption that people are good and basically want the same things → Increased gun control will increase risk

Flaw: This argument assumes that if people are not good or don’t basically want the same things, increased gun control will increase danger.

However, say we aren’t good and don’t want the same things (I certainly don’t want to shoot innocent people, but others apparently do), and a particular “effort at disarmament” makes it hard enough for the “bad” people to arm themselves such that it leads to less total gun violence? Mamet would say this is impossible, but that’s a convenient (and necessary) assumption.

In conclusion, the man probably shouldn’t teach the LSAT. I’d say he won’t ever have to, but you never know.

Yes, I'm a cardinal and yes, I rule. Your point?

Recall the cardinal rule of assumptions: they are unstated. If a question is quoting a portion of text to you, that portion is stated. It cannot, therefore, be an assumption.

These questions that ask you to identify the function or role of a phrase or statement are pretty efficient to answer if you know what you’re looking for. If you identify the quoted phrase as a conclusion, you can knock out any answer choice that calls it premise, no matter how accurate anything else in that answer choice is. Likewise, if it’s a premise, you can get rid of any answer choice that calls it a conclusion.

But regardless of its role, you can always get rid of “assumption” answer choices for one reason: since it’s quoted, that’s impossible.

Check out PT64, S1, Q14 for an example.

Don't let your imagination run wild while filling in the blank

Fill-in-the-blank-line-at-the-end-of-the-argument questions have been known as Inference questions delivered in a fancy package. “These,” I tell students, “ask you to find a conclusion, but don’t start thinking creatively. Your task is still to find an answer that must be true.” This is easy to grasp, since something you can infer from a premise could also be called a valid conclusion. So that was that.

But there’s a different flavor of fill-in-the-blank questions creeping into the LSAT from time-to-time! For example, on PrepTest 63, Section 1, Question 1 and PrepTest 65, Section 4, Question 15, you’re asked to fill in the blank… with something that will strengthen the argument’s conclusion. “Wait!” you’re thinking, “We don’t strengthen conclusions on Inference questions…” That’s right. In fact, on Inference questions, there is no conclusion in the stimulus–your answer could be considered the conclusion. We can think of PT63, S1, Q1 and it’s comrade on PT65, therefore, as Strengthen questions–you want to make the conclusion inferable.
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As you can imagine, being an LSAT teacher carries great risks. What used to be good old fights about doing the dishes are now fights about doing the dishes AND the assumptions underneath the statement “When you leave the dishes on the sink, it makes me feel like you’re an a@#$&@(#!”

But, enough about dishes we have to wash, let’s talk about disposable dishes! Yesterday I went and bought a shredded chicken burrito (half-and-half spicy/mild) at Santiago’s, my second favorite Mexican restaurant. I also picked up a frosty soda to wash it down (“pop” for Midwesterners). It arrived in a lovely Styrofoam cup. Later, while waiting in line (“on line” for New Yorkers), I satisfied my need to be constantly doing something (“ADHD” for you youngins) by reading the cup. I faced these two statements:
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Rick Santorum sure has made some controversial remarks lately. But are they logically sound? Regardless of your political leaning, it pays to know how to evaluate the pieces and soundness of an argument. For this week’s post, I’ve plucked a few Santorum gems to help you review logical reasoning strategy. Can you identify the question types, below? Better yet, can you answer them? Answers after the jump! Read more

It's Big, and it's Not Yellow

You’re going to love it. Take a look at how much we love it:

If you bought our last Logical Reasoning Guide after December 15, 2010, we’ll happily replace the book with a new one so that you can join in the Manhattan LSAT logical reasoning jamboree. If you bought it at a bookstore, send us the receipt, if you bought it through us, just e-mail us the shipping address to use.

Woo-hoo! We like big ducks.

Weaken questions can operate in a few different ways. Let’s look at some examples.

Sep 09 Exam, Section 4, #2

Here’s the basic logic given in the argument:

You can always keep your hands warm by putting on extra layers of clothing (clothing that keeps the vital organs warm).

THUS, to keep your hands warm in the winter, you never need gloves or mittens.

This argument is a sound argument – no flaws or assumptions. If you have another option for keeping your hands warm, then you never truly need gloves or mittens.

In this case, the correct answer actually attacks the main premise. The correct answer says that sometimes (when it’s really really cold) putting extra layers of clothing on actually is not enough to keep your hands warm. Notice how this contradicts the premise. So, to weaken an argument you can attack a supporting premise.

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