Support If one is to participate in the regional band, one must practice very hard or be very talented. ██████████ █████ ███ ██ █████ ██████████ ██ ███ ████████ ████ ███ ██ ████ █████████ ████ ███ ████████ █████
The author states that to be in the band, one must fulfill condition A (practice a lot) or condition B (be very talented). Thus, since Lily is in the band and fulfills condition B, the author concludes that she does not fulfill condition A.
The author doesn’t recognize that “or” on the LSAT is generally inclusive. This means that to be in the band, Lilly can fulfill condition A, condition B, or both. Just because it is only necessary to fulfill one condition doesn’t mean that Lilly can only fulfill one condition.
The parallel flaw will have a conditional statement with 2 necessary conditions A and B, and will conclude that because one condition is fulfilled, the other is not.
The flawed reasoning in which ███ ██ ███ █████████ █████████ ████ ███████ █████████ ███ ██████ █████████ ██ ███ ████████ ██████
In order to ████ █ ██████ ██ ████ ███ ███████████ ███ ████ █████ ████ ███████ ██ █ ████████████ ███ █████████ ███ █████████ ███ ███████ ██ ████ ██████ ██ ███ ████ ████ ████ ███ ███████████
(A) only has one necessary condition: good weather. (A) just concludes that since the army has good weather, it will meet its objectives. This is incorrect (because we don’t know that good weather is a sufficient condition as well as a necessary condition) but it makes a different error from the argument in the stimulus.
If Lois were ██ █████████ ███ █████ ██ ████████ ███ ███████ ██ ███████ ██ ██████ ███████ ██ ████████ █████ ███ ██ ███ ██ █████████ ███ ██ ██ ███████ ███████ ███ ████████
(B) lays out a sufficient condition for being in Chicago or Toronto, and concludes that since the sufficient condition isn’t fulfilled, Louis isn’t in either of the two places. This is an invalid argument, but doesn’t make the “exclusive or” error.
If Johnson is ██ ███ ███ █████ █████████ ████ ███████ █████ ███ ██████ ███ █████ ███ █████ █████ ███████ ██ ████ █████ ██ ████ ███████ ████ ███ ███ █████
(C) says that since a necessary condition (Horan and Jacobs not entering) is true, the conclusion (Johnson will win) is also true. The error here is confusing sufficient and necessary, but (C) doesn’t make the “exclusive or” mistake.
To stay informed █████ ███████ ███████ ███ ████ ████ █ █████ █████████ ██ █████ ████████ ██ ████ █████ ████ ██ ██████ ███ ██ ████████ █████ ███████ ██████ ███ █████ █ █████ █████████ █████ ████ ████ ███ █████ ██ █████
(D) states that to be informed about current events, one must fulfill condition A (read a major newspaper) or condition B (watch TV news) — and concludes that since Julie is informed and fulfills condition A, Julie does not fulfill condition B. This is the same reasoning as in the stimulus, and makes the same error: assuming that “or” is exclusive.
If Wayne is ██ ███ █ ████ ████ ████ ███ ████████ ██████ ██████ ██ █████ ████ ██ ██████ ██████ ██ ███ ██ ███ ████████ ██ █████ ████ ██ ██████
(E) says that to get a ride home, condition A (Yvette being there) or condition B (Marty being there) is necessary. But (E) concludes that since condition A isn’t true, condition B must be. This is different from the stimulus, which concludes that since one condition is true, the other must not be.