#18 - Learning how to build a nest plays an important part

[Dave Killoran]

Complete Question Explanation

Weaken-CE. The correct answer choice is (B)

The stimulus indicates that experience ("learning how to build a nest") plays a role breeding success. That statement is then followed by an example, and examples on the LSAT are typically used to illustrate premises of the argument. In this case, Dr. Snow finds that blackbirds nesting for the first time are less successful than older birds, and less successful then even they are a year later.

The author then rejects two possible causes—size and strength—and concludes that nesting experience is the cause of success in breeding.

Answer choice (A): The argument does not seek to compare different bird breeds, but is instead about is about success over time. Thus, this information does not help us undermine the argument.

Answer choice (B): This is the correct answer choice. This answer suggests that experience is not the cause, but rather a physical ability or maturity within the birds that is allowing for greater success. Since this suggests an alternate cause, this is the correct answer.

Answer choices (C): This answer supports the idea that experience plays a role, and thus this answer strengthens the argument.

Answer choice (D): If this is the case, then experience could still be the cause, and consequently this answer does not weaken the argument.

Answer choice (E): This answer addresses information about the birds before they even start nesting, which means it is about a situation that occurs before the causal relationship being discussed. Answers such as these (or those about what happens after the relationship) are typically incorrect.

[cmorris32]

Hi PowerScore!

I identified B as the correct answer, but I am struggling to understand why A does not introduce an alternate cause. I feel like when I read answer choice A, I thought that Blackbirds' ability to build better nests provides an alternate cause as to their nesting experience. Can you please explain?

Thanks!
Caroline

[Adam Tyson]

We aren't looking for what causes their nesting experience, Caroline, nor are we looking to compare blackbirds to other birds. We are looking to see what causes them to have increased breeding success over time. The author thinks nesting experience is the cause - the more experienced they become at building nests, the more they succeed at breeding. Answer A tells us nothing about why they get better at breeding over time. And building a better nest than another bird doesn't mean that they do or do not improve at nest building over time. They might start out better than all other birds, and continue to improve from there. Answer A is just irrelevant to the causal argument about breeding success.

[cmorris32]

We aren't looking for what causes their nesting experience, Caroline, nor are we looking to compare blackbirds to other birds. We are looking to see what causes them to have increased breeding success over time. The author thinks nesting experience is the cause - the more experienced they become at building nests, the more they succeed at breeding. Answer A tells us nothing about why they get better at breeding over time. And building a better nest than another bird doesn't mean that they do or do not improve at nest building over time. They might start out better than all other birds, and continue to improve from there. Answer A is just irrelevant to the causal argument about breeding success.

Thank you for answering so many of my questions, Adam! I really appreciate it.

[TZHUUMD22]

Hello PowerScore,

So the point here is that "capacity to breed," by virtue of it "increases with each successive trial (meaning breeding?) during the first few years of reproduction" is independent from "experience to nest," am I correct?

Thanks a lot!

T

[KelseyWoods]

Hi TZHUUMD22!

Let's start by breaking down this argument:

Premise: Older birds are more successful at breeding than first time nesters (Observation)
Premise: Size and strength cannot be the cause of why older birds are more successful at breeding because blackbirds are fully grown when they leave the nest. (Rejecting some possible causes of the observation)
Conclusion: Experience in nest building causes success in breeding (Concluding this is the only potential cause of the observation that remains)

On the LSAT, we always accept the premises as true. In a Weaken question, we want to show that the premises given do not necessarily prove the conclusion stated.

In this argument, we accept that older birds are more successful in breeding. We need to attack the author's explanation for this observation--nesting experience. To do that, we need to find another possible explanation for the observation that older birds are more successful in breeding besides nesting (and size and strength, since these were also already discounted in the premises).

Answer choice (B) tells us that the ability of blackbirds to lay viable eggs also increases over their first few years of reproduction. This suggests that the cause of blackbirds increase in breeding success over time may have more to do with their reproductive systems continuing to mature, rather than their ability to build a nest.

So, yes, "capacity to lay viable eggs" is different than "nesting experience" (which is more specifically described as "learning how to build a nest" in the first sentence of the stimulus).

Hope this helps!

Best,
Kelsey

[sj woo]

Hi powerscore,

Though I got the correct answer b, I have problem solving my contradiction here.

From the first sentence, I focused on the term " plays an important part..." and that gave me 'building a nest' as the necessary and forth the diagram goes,
Breeding success building nest
Just to get the answer, I focused for simplicity that the necessary(building nest) is not related to the sufficient.

Here the problem is then I realized the third sentence in the stimulus(He finds that..) is the other way in around , in logic, of the diagram of the first sentence.

I got confusion here and can anyone please give help?
Need explanation what I got wrong...

Thanks,

Seungjae

[Jeff Wren]

Hi Seungjae,

It looks like you're confusing conditional reasoning with causal reasoning.

The phrase "plays an important part in" indicates causal reasoning rather than conditional reasoning.

For example, the statement "eating junk food plays an important part in the high levels of obesity in the United States" does not mean that eating junk food is necessary for obesity. Instead, it means that eating junk food is an important cause of the high levels of obesity, although there may also be other contributing causes.

In "The Logical Reasoning Bible" chapter on causal reasoning, one of the indicators listed under "Partial Cause and Multi-Cause Scenarios" are the words "played a role in." In the stimulus, "plays an important part in" is just a variation of this wording and has a similar meaning.

As for the part of the stimulus that states "he finds that birds nesting for the first time are less successful in breeding than older birds," this is actually a correlation. One common mistake in causal arguments is mistaking a correlation for causation.