Blueprint LSAT Prep's ongoing ask-an-instructor extravaganza Forum

[Captain Rodeo]

Hey BP, thank you very much for the explanation. I see how the other one is too strong.

And I second that, good luck all!

[Captain Rodeo]

Hey Shinners,

Could you help me with SuperPrep C, Section 3 #22?

I see why (D) works over (C), however, I do not at all understand how to diagram (D). It looks like there's two necessary conditions, and no sufficient condition there.

I thought this was a hard problem. It seemed like (C) lined up with what the two speakers were saying quite well, however, it doesn't address the problem of people who work for equal lengths of time (Tahsa's concern) like (D) does.

Oh- I went to Yard House with my cousin and had a White Russian. It was awesome.

EDIT: No, actually I don't think I get this Q at all.

[1TLStudent]

BP Shinners

never got a chance to thank you for the help from before. thanks!

[bp shinners]

Closed
Open

[arcanecircle]

Hey Matt, admin question:

How do schools view legacy applicants? Is this something even considered for state/UC schools, or more a HYS thing? In a slightly similar vein, do alma maters have any sort of edge? Thanks

[bp shinners]

Hey Matt, admin question:

How do schools view legacy applicants? Is this something even considered for state/UC schools, or more a HYS thing? In a slightly similar vein, do alma maters have any sort of edge? Thanks

Outside of the people whose names are on the buildings or in the history books, it won't matter much. Ditto alma maters.

[arcanecircle]

Thanks. You'd be surprised how many people don't believe this.

[hallbd16]

Sorry about the after-hours posting... I am on a 12 hour time differential and have a conflicting schedule... Here is my question for when you open again, if you don't mind:

I read in a LR book that, "in the majority of LSAT questions with 2 speakers, the male makes a mistake or an error of reasoning and the female uses sound reasoning. This doe not occur in every instance, but enough..."

The reason the text cited was b/c it covers LSAC liability...

Have you noticed this trend, heard of it before? Can you speak to the reliability of the statement?

[bp shinners]

Sorry about the after-hours posting... I am on a 12 hour time differential and have a conflicting schedule... Here is my question for when you open again, if you don't mind:

I read in a LR book that, "in the majority of LSAT questions with 2 speakers, the male makes a mistake or an error of reasoning and the female uses sound reasoning. This doe not occur in every instance, but enough..."

The reason the text cited was b/c it covers LSAC liability...

Have you noticed this trend, heard of it before? Can you speak to the reliability of the statement?

Liability for what?

I can't say that I've noticed that trend, but I also can't definitively say that it doesn't exist. I wouldn't rely on it, however, as that's the type of thing that LSAC could use to trick you. Definitely analyze anyone's argument for flaws.

[bp shinners]

Stop - I'm collaborating and listening.

[bp shinners]

Go ninja, go ninja, go!

[meandme]

Hey BP
How about PT40 Sec1 #10.

Thanks

[bp shinners]

Alright, so we've got a flaw question here (though a weird one) - we're looking to see what Olaf doesn't understand about what Charlene is saying.

Charlene:
Enviro cleanup relies a lot on microorganisms to eat the pollution
Microbes become less active when a region's temp drops below normal
_________________________________________
Therefore, this method has its limits

Alright, so microorgs are a decent way to clean stuff up, but we run into a problem when the temperature drops below normal. My problem right now is I don't know what 'normal' means, and I'm expecting that to crop up in Olaf's response - normal for the region? normal for the microorganism?

Olaf:
Researchers did a study of CO2 output of microorganisms
The ones in the Arctic and in the subtropical region ate oil at nearly the same rate
______________________________________
Therefore, I think you're wrong in what you said.

So we have a study that showed Arctic microorgs (cold) and subtropical microorgs (warm) ate oil at the same rate. From that, he's saying that Charlene is wrong because she said that they are less active when the region's temp drops below normal. Olaf is saying that at different temps, these bacteria ate a different rate. However, Charlene could be arguing (and, if we want to presume her argument is valid, is arguing) that the bacteria in that location have a specific temperature band that's 'normal' for that area of the world. When it drops below that, we have problems in that area.

So, in short, Olaf's comparing bacteria in two different locations that might be completely different bacteria, whereas Charlene's comparing bacteria in the same location to bacteria in the same location when it gets colder. That problem of defining 'normal' ended up creating problems in Olaf's response.

[bobbypin]

I am still struggling with sufficient / necessary. When I get the answer right, it's usually because my common sense found the right answer. On the more difficult questions, I am choosing the "mistaken reversal" (from Powerscore). Other than repetition, any other tips for attacking these questions?

Repetition just seems to keep me making the same damn mistake.

[bp shinners]

Ready, set, go

[bp shinners]

I am still struggling with sufficient / necessary. When I get the answer right, it's usually because my common sense found the right answer. On the more difficult questions, I am choosing the "mistaken reversal" (from Powerscore). Other than repetition, any other tips for attacking these questions?

Repetition just seems to keep me making the same damn mistake.

For sufficient assumption questions, you're trying to bridge a gap in the argument.

There are two types of sufficient assumption questions - one where a new term shows up in the conclusion, and one where it doesn't (the latter being more difficult).

If a new term shows up in the conclusion of a sufficient assumption question, you can automatically get rid of any answer choice that doesn't include that term. You'll never have a sufficient assumption that doesn't allow you to bridge the gap created by that new term in the conclusion (barring a few fringe cases).

If a new term doesn't show up in the conclusion, it means the gap in the argument is between two premises. These are more difficult, but they can usually be diagrammed. Diagram them out, see what two terms need to be connected, and pick that answer.

For necessary assumption questions, there will also quite often be a new term in the conclusion. You can likewise get rid of answers that don't include that new term.

If there isn't a new term in the conclusion, then you need to ID the flaw (you've been doing that so far, but the flaw has been equivocation - a new term shows up that doesn't mean the same thing as the terms in the premises). Then, find an answer that addresses the flaw in some way, and negate it to see if it kills the argument.

Sufficient assumption answers tend to be strong, and it's a pretty strong correlation.

Necessary assumption answers tend to be weak and limit themselves to the stimulus's world, though this correlation is weaker than the sufficient assumption. Common incorrect necessary assumption answers will be too strong and talk about situations outside of the stimulus however.

There's a whole 2+ hours I teach on this, so it's hard to get it down to a post. But hopefully this will help you start to get through them!

[sdwarrior403]

I have a current thread on this, but i would like help with PT 45 Section 1 #24

I completely understand that the DNA test can fail to distinguish among individuals, even though each person's DNA is unique. So this means that we could have 3 people: Adam, Bob, and Carol. Even though all three have different DNA, the DNA test could show Adam's DNA being Bob's. The only common sense thing to assume is that Bob has to have some kind of DNA associated with his name for his test. It would not make sense for Bob to also have his own DNA associated with himself as well since Adam already is given that one. So if Bob is given the distinction of having Adam's DNA, then obviously an exonaration is not justified.

How does the above situation not consistent with the argument? It seems that situation I present is allowing for the failure of distinguishing individuals.

[bp shinners]

The only common sense thing to assume is that Bob has to have some kind of DNA associated with his name for his test. It would not make sense for Bob to also have his own DNA associated with himself as well since Adam already is given that one. So if Bob is given the distinction of having Adam's DNA, then obviously an exonaration is not justified.

I'm not 100% sure what you're saying here, but I think I have the gist of it.

So in your situation, Bob, Adam, and John (I'm making them all male because you can tell male vs. female DNA based on chromosomal make-up, but that's in no way necessary for this argument to work - I'm just being a science elitist) all have different DNA.

When we're testing the DNA, we're not trying to associate it with a person - we're trying to see if it matches a sample we have. In the case at present, we have DNA from a crime scene. We're trying to match Bob, Adam, or John to it to find out who committed the crime.

In other words, I'm not trying to match a sample to an individual, which is what I think you're trying to do - instead I'm trying to match an individual to a sample.

The stimulus tells me that sometimes I can't distinguish between DNA samples taken from distinct individuals - in other words, sometimes I get a false positive. John might come up as a match even though he didn't commit the crime.

From this, the argument concludes that if someone does NOT match the DNA, we can't exonerate them.

That's not what I just established - I talked about false positives (a match when there really isn't one), not false negatives (no match when there really is one). Since I haven't established that DNA testing results in false negatives (for instance, John committed the crime, but his DNA didn't match the crime-scene DNA in the test), I haven't proven my conclusion that we can't exonerate someone whose DNA doesn't match.

B gives me just that - it confuses a false positive (a test that incorrectly identifies DNA samples as coming from the same person) with a false negative (a test that incorrectly shows as coming from a different person samples that come from a single person).

I think you got a little tripped up on the science in this one - I'm not talking a DNA database where I have everyone's DNA. Instead, I'm taking a skin sample from underneath the victim's finger and comparing it to DNA I took from the three suspects. I'm not comparing Adam's DNA to Bob's, or taking a random DNA sample and trying to match it to a suspect. I'm taking DNA from the suspects and matching it to a sample from the crime scene.

[sdwarrior403]

in other words, sometimes I get a false positive. John might come up as a match even though he didn't commit the crime.

This is the part where I trip. How is John coming up as a match when he did not commit the crime? Are you telling me that one of the other 2 suspects did in fact have the DNA match the crime scene? If so, how are you confident that the criminal is not coming up as a match?

[bp shinners]

in other words, sometimes I get a false positive. John might come up as a match even though he didn't commit the crime.

This is the part where I trip. How is John coming up as a match when he did not commit the crime? Are you telling me that one of the other 2 suspects did in fact have the DNA match the crime scene? If so, how are you confident that the criminal is not coming up as a match?

"DNA tests often fail to distinguish among DNA samples taken from distinct individuals."

That means sometimes when testing DNA it doesn't always distinguish the DNA I got from a person and the sample against which I'm comparing it - sometimes I get a false positive.

So sometimes the DNA at the crime scene will match the criminal AND John, even if John didn't commit the crime. It might also match other people.

And I'm not confident that the criminal isn't coming up as a match - in fact, the argument suggests the criminal will come up as a match. However, the argument also lets me know that it's not ONLY the criminal coming up as a match - sometimes, other people come up as a match as well, people who had nothing to do with the crime.

[sdwarrior403]

Thanks so much for your help. BTW, how would this situation play out in real world science? How does the test fail to distinguish between a samples from individuals.

[bp shinners]

Thanks so much for your help. BTW, how would this situation play out in real world science? How does the test fail to distinguish between a samples from individuals.

When you're comparing DNA samples, there are certain areas of the strand you look at in order to make the comparison. The more points you look at, the less likely it is that two random people are identical. That's why on shows you'll hear about "6 point DNA matches", and stuff like that. The science isn't represented perfectly on the shows, but you can get the general idea.

If you're only matching across a few markers, you might have 10,000 people on the planet who would match that sample. The chances of one of those other 10,000 people being the target of an investigation AS WELL AS the actual criminal is relatively small, but it exists. If you increase the number of markers, however, that number gets smaller (say 1,000 other people with that series of markers), and the chances of a false positive decreases as a result.

Add to that the degradation of DNA from crime scenes, and you can start to see how lawyers can poke holes in the certainty of the science.

[sdwarrior403]

Thank you for that information.

[bp shinners]

Let's go.

[meandme]

Hey BP
How about PT40 Sec3 #15 SA (doctorates in liberal arts)

Thanks