This post is part of an ongoing series of question explanations for the LSAT. In this post, I explain LSAT PrepTest 52, Section 3, Question 13. If you are looking for a copy of PrepTest 52, check out my post on where to find LSAT PrepTests. If you already have a copy, keep it on hand as you read the explanation.
Question Type: Complete the Argument
Complete the argument questions require us to 1) analyze the argument, 2) determine what the argument is missing, 3) choose the answer that best provides the argument with what is missing.
Analyze the Argument
The argument begins by telling us about what “some paleontologists” believe. Specifically, we are told that these paleontologists believe that certain dinosaur species would guard their offspring in “protective nests” for a long time after the offspring hatched from their eggs. Note that we don’t know yet what the author of this argument believes about the dinosaurs and guarding offspring; the argument so far has only told us about an opinion held by “some paleontologists.”
The second sentence in the argument provides us with the evidence that “some paleontologists” use to back up the belief mentioned in the first sentence. Specifically, the evidence is that fossils have been found of young hadrosaurs in carefully constructed nests. Once again, we have been given no information about what the author of the argument believes. We are still only talking about “some paleontologists.”
The third sentence in the argument is a rebuttal to the evidence mentioned in the second sentence. Here we learn that crocodiles construct similar nests to the hadrosaurs nests found. Yet, crocodiles only guard their offspring for a short period of time. In this sentence, we finally see the author’s opinion start to come out. The author is providing us with a reason to doubt the evidence mentioned in the second sentence! Thus, we can infer that the author is arguing against that evidence.
Determine What the Argument is Missing
The final sentence of the argument begins with the word “hence,” so we know that this is some sort of conclusion based on what we have seen already in the argument. And our argument is indeed missing main conclusion! The third sentence gives us a reason to doubt the evidence mentioned in the second sentence, but the author has yet to make any assertions about the evidence! What we need is an answer that claims the evidence does not provide us with a reason to believe that certain dinosaur species would guard their offspring in “protective nests” for a long time after the offspring hatched from their eggs. That’s the conclusion that would be supported by the argument.
Choosing the Answer
Answer A: This is tempting but wrong. First, the answer is a bit too strong. The author never supports the idea that there is “no evidence.” Maybe there’s other evidence out there that the argument does accept! Second, our answer would ideally talk about more than just hadrosaurs. The evidence only mentions hadrosaurs, but “some paleontologists” are using the evidence to make a claim about multiple species of dinosaurs.
Answer B: Again, our answer would ideally talk about more than just hadrosaurs. But even if this answer did talk about more dinosaur species, it would still be wrong. The argument never supports the idea that we will never find good evidence!
Answer C: Again, our answer would ideally talk about more than just hadrosaurs. But there’s a bigger criticism we can make of this answer! The author is rebutting the evidence mentioned in the second sentence, not rebutting the claim made in the first sentence. We know this because of the third sentence. Notice how the third sentence gives us no reason to reject the claim mentioned in the first sentence; it only gives us a reason to doubt the evidence mentioned in the second sentence.
Answer D: Again, we don’t know that the hadrosaur is one of the dinosaurs discussed in the argument. But even if we did, this answer would still be wrong as it is completely out of scope for the argument.
Answer E: Correct! If crocodiles that don’t guard their young for long periods of time have similar nests to the dinosaurs being discussed, then the dinosaur nests by themselves are not sufficient to show the dinosaurs did guard their young for long periods of time. This is supported by the third sentence of the argument, and it makes sense as a conclusion.