"If the recording now playing on the jazz program is really 'Louis Armstrong recorded in concert in 1989,' as the announcer said, then Louis Armstrong was playing some of the best jazz of his career years after his death."
Ultimately the sufficient condition is made up of two variables: that the music being played is by Louis Armstrong, and that, as the announcer said, it is from a concert in 1989. So, let's diagram.
P1: LA &1989 ==> LABJAD ("Louis Armstrong plays some of his best jazz after his death" = IMPOSSIBLE) not LABJAD ==> not LA or not 1989
"Since the trumpeter was definitely Louis Armstrong,"
P2: LA
"somehow the announcer must have gotten the date of the recording wrong."
C: not 1989
Ultimately, we are given two variables that make up the sufficient condition to infer something that is impossible. We know that the not impossible option, i.e. "not LABJAD," is true.
Thus, according to the contrapositive of P1, either it is not Louis Armstrong singing or the song was not from a concert in 1989. Well, we know that it was, in fact, Louis Armstrong, therefore, "the announcer must have gotten the date of the recording wrong."
Answer choice (C) has this exact pattern of reasoning.
"Only if a twentieth-century Mexican artist painted in Japan during the seventeenth century can this work be both 'by Frida Kahlo' as labeled and the seventeenth-century Japanese landscape it appears to be."
Remember that "only if" introduces a necessary condition. The two variables in this sufficient condition are "the work being done by Frida Kahlo, as labeled," and it "representing the seventeenth-century Japanese landscape." So, let's diagram!
P1: FK & 17th ==> 20thMA17th ("work is done by a 20th century Mexican artist that painted in Japan during the seventeenth century" = IMPOSSIBLE). not 20thMA17th ==> not FK or not 17th
We will use the contrapositive since we know that the work cannot be done by a 20th century Mexican artist that painted in Japan during the seventeenth century. So, either the work is not done by Frida Kahlo, as labeled, or it is not the seventeenth-century Japanese landscape as it appears to be. Well, we know that it is the seventeenth-century Japanese landscape as it appears to be. Thus, the work was mislabeled.
Hope that helps! Please let us know if you have any other questions.
Julie-VAugust 3, 2019
I was between (C) and (E) but ultimately chose the latter. Could you explain why (E) is incorrect? Thank you!
RaviAugust 3, 2019
@Julie-V,
Happy to help. Let's look at (E).
(E) says, "If this painting is a portrait done in acrylic, it cannot be by Elisabeth Vigee-Lebrun, since acrylic paint was developed only after her death. Thus, since it is definitely a portrait, the paint must not be acrylic."
(E) is tricky, but it doesn't include any information about a description, which was a crucial piece of the argument from the stimulus. Thus, we can get rid of (E).
Does this make sense? Let us know if you have any other questions!
