Brownlea’s post office must be replaced with a larger one. The present

OFFICIAL EXPLANATION

OA : (B)

OE : Curve ball: The argument starts off with one argument (sentences one + two: We must build a new post office because the old one can’t be expanded), but moves past that first decision to another, more problematic one: Where can the building be built cheaper? The conclusion that the outskirts site is “clearly” cheaper is the one we seek to undermine. Sure, land is cheaper on the outskirts than in town. But what (you may well have asked yourself) about other factors—other issues that might impact the cost? If (B) is true, then there’s a major cost of the outskirts site, building a parking lot, that wouldn’t be incurred in town. Notice that (B) doesn’t prove that the center of town would be the cheaper site. It simply casts doubt on the certainty of the author’s judgment that building on the outskirts would be cheaper. Given (B), we’re left with a need for more evidence in order to choose between the center location with its land costs, and the outskirts site with its parking lot costs. And the very need for more evidence proves that the argument has been undermined.


(A) Even assuming that that new building code would affect the cost of construction at all, let alone in a major way, this code inferably applies to both sites and hence cannot affect the site comparison.

(C), (D) Running extra buses to the outskirts site (C), or delivering more mail (D), would likely cost the city a few bucks. But they’re not construction bucks—they’re not part of the
building costs—and the argument is specifically about which site would be cheaper to build. Therefore, neither choice has any effect on the logic whatsoever.

(E), if anything, strengthens the logic. Adding yet another cost (however much it may cost to work nights and weekends) to the city center site makes the outskirts site seem that much cheaper in comparison.

• Often, when an LSAT question asks you to weaken logic, two or three of the choices will be outside the scope while one will act as a strengthener. Not a hard and fast
rule, but a useful pattern to know of and watch for.

• Principle: Forcing the author to come up with more evidence to support her conclusion is proof that that conclusion has been undermined. (B) illustrates this quite well; see explanation above.