Self-study
Support People with higher-than-average blood levels of a normal dietary by-product called homocysteine are twice as likely to be diagnosed with Alzheimer's disease as are those with average or below-average homocysteine levels. █████ ██ ██ ██████ ████ ███ ████ ██ ██████████ ███████████ ███████ █████ ██ ███████ ██ █████████ ██ █████ ████ █████ ███████ ██ █ ████████ ███ █████ █████ █████ ███████ ████████████ ████ ██████████ █████ ██ ████ ██ ████████ ██ ███████████ ████████
Summarize Argument: Phenomenon-Hypothesis
The author concludes that Alzheimer’s risk can be reduced by converting homocysteine into other substances. This is based on the fact that people with above-average levels of homocysteine have higher risk of being diagnosed with Alzheimer’s.
Notable Assumptions
The author assumes that there’s no other explanation for the correlation between above-average homocysteine levels and increased risk of Alzheimer’s.
21.
Which one of the following, ██ █████ ████ █████████ ███████ ███ █████████
a
Many Alzheimer's patients ████ ██████ ████████████ ███████
A correlation between above-average homocysteine and Alzheimer’s allows for outliers. There can be Alzheimer’s patients with normal or even below-average homocysteine levels.
Illusory inconsistency
Illusory inconsistency
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion.
b
The substances into █████ ████████████ ██ █████████ ███ █████████ ████ ███████ ███████ █████████ ██ ███████████ ████████
If the effects are unrelated to Alzheimer’s, then they have no impact on the conclusion, which is focused only on whether Alzheimer’s can be reduced by converting homocysteine to those substances.
c
B vitamins and █████ ████ ███ ███ ███████████ ██ ███ ████ ████ ███████████ ████ █████ ██ ███ ████ ██ ███████████████ ████████████
This just suggests B vitamins and folic acid should be taken in other forms besides vitamin-mineral supplements. The author never suggested any specific form in which we take B vitamins and folic acid.
d
People whose relatives ██████████ ███████████ ███████ ███ ████ ████ ██████ ██ ███████ ███████████ ████ █████ █████ █████████ ███ ████
This suggests that there’s also a genetic component to Alzheimer’s. But there could be a genetic component to having higher homocysteine levels. In addition, it’s possible for there to be multiple, independent causes of Alzheimer’s.
Failed alternate explanation
Failed alternate explanation
Weaken Qs: Answers that try to introduce an alternate explanation, but fall short, or try to explain a different phenomenon.
Strengthen Qs: Answers that try to eliminate an alternate explanation, but fall short, or try to eliminate an explanation for a different phenomenon.
e
Alzheimer's disease tends ██ ████████ ███ ██████ ██ ████████████ ██ ███ ██████
This provides an alternate explanation for the correlation observed. If Alzheimer’s increases homocysteine, we’d expect people with Alzheimer’s to have higher levels of homocysteine, even if homocysteine doesn’t cause Alzheimer’s.
Alternate explanation
Alternate explanation
Weaken: Introduce or support an alternate explanation for a phenomenon.
Strengthen: Helps to eliminate an alternate explanation for a phenomenon.