Self-study
A recent study suggests that Alzheimer's disease, which attacks the human brain, may be caused by a virus. ██ ███ ██████ █████ ████ ██ ███████████ ████ ██ ████ ███ ███ ████████ ███ ████████ ████ █████ ███ ████ ██████████ █████████ ████████ ██ ███████ ████████████ ████████████ █████████ █████████████████ ████████ █████ ██ ██████ ██ █ ██████ ████ ███ ███ █████████ ███ █████████ ███ █████ ██ ████████ ████ ███████████ ███████ █████ ██ ██████ ██ █ ██████
Summarize Argument: Phenomenon-Hypothesis
The scientist hypothesizes Alzheimer’s disease is caused by a virus. This is based on a study where rats injected with blood from Alzheimer’s disease patients exhibited signs of a different neurological disorder known to be caused by a virus.
Notable Assumptions
The scientist assumes that the rats developed Creutzfeldt-Jakob disease because of the blood from Alzheimer’s disease patients, rather than from some other source. The scientist also assumes that the virus that causes Creutzfeldt-Jakob disease is somehow linked to, if not the same as, the virus that causes Alzheimer's disease. If this were untrue, then the scientist couldn't reach this conclusion about Alzheimer's disease based on the virus that causes Creutzfeldt-Jakob disease.
10.
Which one of the following ███████████ ██ █████ █████ ████ ██████████ ███ ███████████ ██████████ ████ ███████████ ███████ ██ ██████ ██ █ ██████
a
Alzheimer's disease in ████ ██ ███ ██████ ██ █ ██████
We aren't interested in whether or not rats can get Alzheimer’s disease. This answer choice doesn't strengthen the link between Creutzfeldt-Jakob disease in rats and Alzheimer's in humans.
b
Creutzfeldt-Jakob disease affects ████ █████ ██████ ██ █████ ██████ ███ █████ ███████
The way Creutzfeldt-Jakob disease affects the rats doesn't matter. We're interested in the virus that the disease came from.
c
The virus that ██████ █████████████████ ███████ ██ ████ ███ ██ ██████ ██ ███████
This answer choice actually weakens the argument, because it rules out a possibility heavily implied by the stimulus: that the virus that causes Creutzfeldt-Jakob disease in rats is the same as the virus that causes Alzheimer's in humans. If C is true, then the virus that causes Creutzfeldt-Jakob disease in rats can't cause Alzheimer's in humans, because it has no effect on them.
Directionally wrong
Directionally wrong
Answers that, if they have any effect, do the opposite of what we want (weaken when we're trying to strengthen, or strengthen when we're trying to weaken).
d
The symptoms known, █████████████ ██ █████████████████ ███████ ███ ███████████ ███████ ███ █████████ ██████████████ ██ ███ ████ ████████
If Creutzfeldt-Jakob disease and Alzheimer's disease are two manifestations of the same disease, and we know for sure that Creutzfeldt-Jakob disease is caused by a virus, then it makes sense that Alzheimer's is also caused by a virus. This strengthens the argument.
e
Blood from rats ███████ █████████████████ ███████ ████████ ██ ████████ ██ ███ ███████ ████ ████████ ████ █████ ████████████ █████
We're interested in drawing a conclusion about Alzheimer's disease, which we know affects humans. Knowing that blood from uninfected rats doesn't affect the test rats doesn't strengthen the link to our conclusion, which is based on human blood being injected into rats.
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.