LSAT 144 – Section 4 – Question 18

LSAT 144 - Section 4 - Question 18

October 2015

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT144 S4 Q18
+LR
Necessary assumption +NA
Causal Reasoning +CausR
Eliminating Options +ElimOpt
A
34%
163
B
5%
157
C
6%
159
D
3%
154
E
52%
167
152
163
175
 +Hardest 147.675 +SubsectionMedium

Live Commentary

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For several centuries there have been hairless dogs in western Mexico and in coastal Peru. It is very unlikely that a trait as rare as hairlessness emerged on two separate occasions. Since the dogs have never existed in the wild, and the vast mountainous jungle separating these two regions would have made overland travel between them extremely difficult centuries ago, the dogs must have been transported from one of these regions to the other by boat, probably during trading expeditions.

Summary
The hairless dogs in Mexico and Peru must have been transported by boat from one of those two countries to the other, and probably during trade.
Why must they have started in either Mexico or Peru? Well, they wouldn’t have just turned up out of nowhere in both countries. Hairlessness likely didn’t originate twice, so both sets of dogs probably originated a single place.
Why must they have come by boat? They’ve never existed in the wild, so to arrive anywhere else, they must have come with humans. And overland travel between Mexico and Peru was very difficult back when these dogs appeared in those countries.

Notable Assumptions
The author hypothesizes that boats are the answer because overland travel would have been so difficult. But he never says whether boats were any easier. He’s implying a comparison (overland harder, boats easier) without actually supporting that comparison. So he must assume that travel between the two countries was indeed easier by boat than by land.
He also assumes that the dogs weren’t transported to both Mexico and Peru from some other location(s).

A
Hairless dogs have never been found anywhere except in the regions of western Mexico and coastal Peru.
The author assumes the dogs weren’t transported to both Mexico and Peru from some other location(s). But he doesn’t assume they’ve never been found anywhere else. What if they were transported from Mexico to Peru, and then to Argentina? That wouldn’t damage the argument.
B
Most of the trade goods that came into western Mexico centuries ago were transported by boat.
Too strong. The author doesn’t need to assume that most trade from all places to Mexico was by boat. He just needs to assume that there were at least some trade expeditions running between Mexico and Peru.
C
Centuries ago, no one would have traveled between western Mexico and coastal Peru by boat except for the purposes of carrying out a trading expedition.
Too strong. The author doesn’t need to assume that all boat travel was for trading expeditions—just that at least some boat travel was (enough to make it likely that the dogs were on some of those expeditions).
D
If hairless dogs were at one time transported between western Mexico and coastal Peru by boat, they were traded in exchange for other goods.
Whether the dogs were traded during trade expeditions is irrelevant. The author merely assumes that there was some way for the dogs to be present on those expeditions. Perhaps they were brought as gifts rather than exchanged, or perhaps they were there by accident.
E
Centuries ago, it was easier to travel by boat between western Mexico and coastal Peru than to travel by an overland route.
The author implies a comparison between overland and boat travel but never says how difficult boat travel was. He must assume boat travel was easier. Otherwise, if it was just as hard or harder than overland travel, the conclusion becomes unsupported or even anti-supported.

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LSAT PrepTest 144 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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