gurpreet07 wrote:
Learning how to build a nest plays an important part in the breeding success of birds. For example, Dr. Snow has recorded the success of a number of blackbirds in several successive years. He finds that birds nesting for the first time are less successful in breeding than are older birds, and also less successful than they themselves are a year later. This cannot be a mere matter of size and strength, since blackbirds, like the great majority of birds, are fully grown when they leave the nest. It is difficult to avoid the conclusion that they benefit by their nesting experience.
Which one of the following, if true, would most weaken the argument?
(A) Blackbirds build better nests than other birds.
(B) The capacity of blackbirds to lay viable eggs increases with each successive trial during the first few years of reproduction.
(C) The breeding success of birds nesting for the second time is greater than that of birds nesting for the first time.
(D) Smaller and weaker blackbirds breed just as successfully as bigger and stronger blackbirds.
(E) Up to 25 percent of all birds are killed by predators before they start to nest
Source: LSAT
The key to (B) is understanding the term "capacity." In this context, it means ability - kind of like in a physiological context. In other words, (B) says that it is NOT the nesting experience that leads to more success in breeding but RATHER it is the adaptation of their bodies - every time they lay eggs, they get better!
-Year 2 of breeding was more successful than Year 1; Year 3 was more successful than Year 2
-This cannot be explained by size and strength
-It must be explained by their nesting experience
I simply want to show why it is NOT the nesting experience that led to this. Maybe the blackbirds get progressively healthier during their first years of nesting. Either way, I just want to show an alternative explanation as that is basically the best way to weaken this claim.
(A) "Other birds?" Who cares?
(B) Yea! If the ability to lay more viable eggs increases, then it is NOT the nesting experience but rather their physiology that explains the uptick in success: their eggs are more viable!
(C) We basically already knew this: premise booster.
(D) This actually strengthens by ruling out an alternative explanation. It says that strengthen and size don't matter! Thus, we couldn't just say, "well during the 2nd and 3rd years the birds were stronger or bigger!" to weaken this claim because (D) says, "not so fast! Those things don't matter!" Whenever we rule out an alternative explanation, we are strengthening the argument if just by a little.
(E) "All birds" is too wide of a scope and we don't care about happens before they start to nest - we care about what happens after!
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