Q3 - Science Columnist: It is clear

[ohthatpatrick]

What does the Question Stem tell us?
Weaken

Break down the Stimulus:
Conclusion: "Having similar genes" is why humans have so many diseases in common with cats.
Evidence: Many human diseases are genetically based. Other than primates, cats are the most genetically similar mammal to humans. All the genes we've found in cats also show up in humans.

Any prephrase?
Whenever we're evaluating an author's explanation, we have two pressure points:
"How ELSE could we explain the same data/phenomenon?"
and
"How PLAUSIBLE is the author's explanation?"

The author has done a lot to support the plausibility of her explanation. And it's more common for a Weaken answer to provide an alternate explanation. But a correct answer could also decrease the likelihood that cats and humans get the same genetically based diseases (there's a conditional claim in the final sentence. If it's in cats, it's in humans. But that doesn't work both ways. So humans potentially have lots of extra genes that cats don't have. If our genetically based diseases come from THOSE extra genes, we've attacked the plausibility of the author's explanation).

Correct answer:
B

Answer choice analysis:
A) "Resistance" is irrelevant. We only care about WHY cats and humans have a lot of diseases in common. This doesn't speak to the author's explanation (similar genes) or to any other explanation.

B) Correct! This answer ATTACKS PLAUSIBILITY of author's explanation. How could "similar genes" be the right cause of our shared diseases if most of our shared diseases have no genetic basis?

C) We are only concerned with explaining why cats have lots of disesases in common with HUMAN primates. The only sense in which nonhuman primates are relevant is that nonhuman primates share a lot of (primate) genes with humans. So if "similar genes" is causing cats and humans to have diseases in common, then cats should also have diseases in common with other primates. This answer basically strengthens by increasing the plausibility of a genetic underpinning to these diseases.

D) "diagnosed" and "mild" are irrelevant.

E) This does nothing. It is practically repeating the 2nd sentence of the stimulus, although the meaning is subtly different.

Takeaway/Pattern: When you're evaluating an Explanation, there are two possible pressure points: 1. Deal with some OTHER way to explain/interpret the same background fact. 2. Address the PLAUSIBILITY of the author's explanation/interpretation. Our correct answer here did #2.

#officialexplanation

[chike_eze]

Correct = (B)
Question Type: Weaken

The argument: Humans and cats have many diseases in common because...
1) many human diseases are genetic
2) cats and humans are very close genetically (except for non-human primates)
3) Humans have all the genes identified in cats

We need to weaken the connection between the premise and conclusion, i.e., genes in common; therefore, diseases in common

B) "Most diseases shared between cats and humans are not genetic based" this weakens the connection between the author's "gene" premise and "disease" conclusion

A) "Cats built up resistance to shared diseases" -- this is irrelevant. We are concerned with why cats and humans have many diseases in common, not if Cats have immunity to them.
C) "Cats.. more diseases in common with non-human" -- Okay, but why do cats share many in common with humans? This does not get at the gap in the argument
D) "Many common diseases = mild, not diagnosed" -- Irrelevant. Whether the diseases are mild or severe does not weaken the argument.
E) "Humans share more genes with non-human primates" -- Out of Scope. Even if this were true, it still does not attack the author's argument.

[noah]

Good explanation! I think this isn't a particularly tricky question to get right, but it's hard to identify the core. Notice that in your explanation you didn't really say what the conclusion is.

I'd say it's this:

Conclusion: Humans and cats have many diseases in common because of their similar genetic make-ups.

Premise: Cats are genetically closer to humans than any other mammal expect apes. Also, many diseases are genetically based.

The gap becomes obvious if you noticed that "many." So what if 60% of diseases are genetically-based. If the ones that cats and humans share in common are in the 40% that aren't, then why even mention genetics? That's what (B) brings up.

I love your wrong answer analysis:

A) "Cats built up resistance to shared diseases" -- this is irrelevant. We are concerned with why cats and humans have many diseases in common, not if Cats have immunity to them.

C) "Cats.. more diseases in common with non-human" -- Okay, but why do cats share many in common with humans? This does not get at the gap in the argument

D) "Many common diseases = mild, not diagnosed" -- Irrelevant. Whether the diseases are mild or severe does not weaken the argument.

E) "Humans share more genes with non-human primates" -- Out of Scope. Even if this were true, it still does not attack the author's argument.

[chike_eze]

@Noah,

I think you make a good point about making sure to point out the conclusion and premise(s). Even though I feel I am pretty good at intuitively honing in on the conclusion, sometimes I completely get the conclusion wrong!

Usually, on assumption/weaken/strengthen questions, I tend to skip steps and go for -- Okay what's the gap? What was said here that wasn't said there?... O I see, the author is assuming that X is equivalent to Y. The correct answer must connect/weaken /strengthen the relationship between the terms.

I've been burned a few times where because I didn't pay attention to the flow of the argument, i.e., what's the conclusion and premise, I ended up picking the wrong choice that had the conditional flow backwards. (Not sure if this is making much sense...)

Anyways, thanks for the input.

[WaltGrace1983]

I hate it when the conclusion is more or less implied than stated, as when the author says "It is clear why..." without ever see "why" it actually is. I liked your analysis though. Here is mine:

"Human diseases are genetically based
+
Cats are genetically closer to humans than are any other mammals (except primates)
-->
Diseases are caused by genetics

Question Type: Weaken

My Thought Process: When I read this stimulus I didn't know what to think. I was thinking that the answer choice would be something along the lines of ""non-human primates have very few diseases in common with humans"" but I didn't find anything like that. This was one of those questions that I knew was flawed but I didn't know which way that the test was going to attack the flaw in the answer choices. The argument is basically saying that, because human diseases are genetic based and because cats are closer to the genetics of humans than other mammals, cats and humans must have the same diseases because they have the same genetics. This looks to me mostly like a correlation - causation problem. Just because these two things are correlated doesn't mean that one necessarily caused the other.

(A) Just because cats have built up resistance doesn’t tell us really anything. We are looking for a way to weaken this argument! This doesn't really do it. It doesn’t really do much of anything. It just provides some fact that is moot to the overall point.

(B) Bam! Argument destroyed! This is correct because it is saying this: "look here though! These diseases that they have in common have nothing to do with genetics!" This answer choice is really getting back to the correlation-causation problem that we discussed earlier. It is saying that all of this is just a coincidence. They have similiar diseases but this isn't because of genetics because the nature of the diseases ensures that it cannot be!

(C) This might strengthen the argument! If cats and humans have a lot of similiar diseases and also similiar genetics and cats and primates have a lot of similiar diseases and (because of the primates' relationship to humans) we can assume that cats and primates are similiar in genetics too, maybe this is all pointing us more in the direction that the genetics are the reason for the diseases. This one looks really tempting because of its wording, it has a lot of good stuff in there. Ultimately though, it is just about the opposite of what we want!

(D) This is very similar to A. Why do we care about this? We don't really. It doesn’t matter if they are mild; it doesn’t matter if these diseases aren't often diagnosed. We are looking for a link (or, really, a breakage of the link) between "genetics" and "diseases." This is really just talking about those diseases - we need more!

(E) This is already in the stimulus. It just boosts it as the stimulus says that the only thing closer to humans than cats in terms of genetics is nonhuman primates.