Self-study
Support One of the effects of lead poisoning is an inflammation of the optic nerve, which causes those who have it to see bright haloes around light sources. ██ █████ ██ ███████ ███ ████████ ██████ ███████ ██ ███ ████████████████ ██████████ ███ ████ ████ ██████ ███████ █ ███████ ██████████ █████ █████ ██ ███ █████ ██████████ ███ ████ ███████ ██████ ██████ ██████ ███ █████ ███ ████ ██ ██ ██████ ████ ██ ███ █████████ ████ ████ █████████ ██████ ██ █████████ ███ ████████ ██ █████
Structure: Phenomenon-Hypothesis
The stimulus tells us that lead poisoning can inflame the optic nerve and cause people to see bright haloes around light sources. We are then told that Van Gogh used a pigment containing lead in his "Sunflowers" paintings. The last sentence informs us about a phenomenon — Van Gogh later painted bright haloes around the stars and sun — and based on the preceding information, we're given a hypothesis to explain this phenomenon: Van Gogh was suffering from lead poisoning caused by ingesting his pigments.
Analysis: Necessary Assumption
Notice the sudden mention in the last sentence of Van Gogh "ingesting" his pigments. Clearly, an assumption necessary for this hypothesis to be true is that Van Gogh did ingest his pigments — if he never did, then the argument would fall apart. It's quite possible the LSAT added this obvious assumption as bait, and the answer choices will contain more subtle necessary assumptions. But this will work as a pre-phrase as we go into the answer choices.
13.
Which one of the following ██ ██ ██████████ ██ █████ ███ ████████ ███████
a
In Van Gogh’s █████ █████████ ██ ███████ ████ ██████ ██ ██ ███ █████
Correct. This is a much more subtle assumption than what we identified in our analysis, but imagine negating (A): "In Van Gogh's later paintings, he painted nothing as he saw it." If this were true, then this would mean that the haloes in his later paintings don't actually represent what Van Gogh actually saw. This would completely destroy the case that Van Gogh had lead poisoning and must have been seeing the haloes as a result.
b
Van Gogh continued ██ ███ ██████ ██████████ ████ █████ ██████ ███████ ███ ████████████████ ██████████
Irrelevant. We don't know how much lead someone has to consume to experience the effects described in the stimulus, how long those effects take to show up, or how long those effects last. So even if we negate (B) to say that Van Gogh never used paints containing lead after the "Sunflowers" paintings, it could still be possible for the haloes in his later work to be the result of lead poisoning from pigments he ingested while painting the "Sunflowers" paintings. Since negating (B) doesn't destroy the argument, (B) isn't a necessary assumption.
c
Van Gogh did ███ ████ ████████ ██ ████ █████████ █████ ████ ██████ ██████ ██████ ██████ █████ ████████
Incorrect. (C), far from being a necessary assumption, might actually weaken the argument if it were true. For all we know, other conditions besides lead poisoning can cause people to see haloes. If Van Gogh only saw haloes and experienced no other symptoms of lead poisoning, this might suggest that there was another cause for Van Gogh seeing haloes, thus weakening the argument in the stimulus.
d
The paints Van ████ ████ ██ ███ ████████████████ █████████ ███ ██ █████ ███████████ █████ ████ █████
Incorrect. Even if we negate (D) to say that the paints Van Gogh used in his "Sunflowers" paintings did contain other toxic ingredients, this wouldn't destroy the argument. It could still be lead poisoning from ingesting those pigments that specifically caused him to see the haloes he later painted, regardless of the effects the other toxic ingredients may have had.
e
The effects of ██████ ██████ █████ ███ ████ ████ ████████ █████ █████ █████████
Incorrect. Negating (E) to say that Van Gogh could have used other pigments doesn't destroy the argument, because it doesn't change the fact that he did use Naples yellow.