Self-study
Journalist: A recent study showed that Support people who drink three cups of decaffeinated coffee per day are twice as likely to develop arthritis—inflammation of joints resulting from damage to connective tissue—as those who drink three cups of regular coffee per day. ████████ █████████████ ██████ ████ ███████ █████████ ████ ███████ ██████████ ██████ ███ ████ ██ ███ ███████ ██ ███████ ███████
Summarize Argument: Phenomenon-Hypothesis
The journalist's conclusion is the claim that something present in decaffeinated coffee, but not regular coffee, damages connective tissue. This claim is based on a study showing that people who drink three cups of decaffeinated coffee per day are twice as likely to develop arthritis as those who drink three cups of regular coffee per day.
Notable Assumptions
Based on a mere correlation, the journalist assumes that decaffeinated coffee causes damage to connective tissue. By assuming causation from correlation, the journalist assumes that some third factor isn't actually causing the difference in arthritis rates. For instance, if people who drink decaffeinated coffee tend to have less healthy diets than people who drink regular coffee, this could explain the different rates. The journalist also assumes that the rates of developing arthritis for decaffeinated coffee actually come from something in decaffeinated coffee that damages tissue. But if drinkers of both decaffeinated coffee and regular coffee have lower rates of arthritis than the general population, then it would be possible that decaffeinated coffee just contains less of a beneficial compound than regular coffee does, instead of containing something that causes damage.
5.
Which one of the following █████ ██ ████ ██████ ██ ████ ██ █████ ██ ████████ ███ ████████████ █████████
a
whether people who ████████ █████████ ███ ████ ██████ ██ █████ █████████████ █████████ ████ █████ ███ ██ ███
For this answer choice to be relevant, we would need to know whether exercising regularly is connected to arthritis--but we aren't told that there is any relationship. Even if we knew exercise was related to arthritis, we would need to know the difference in exercise rates between people who drink decaffeinated coffee and people who drink regular coffee, not the difference in likelihood of drinking decaffeinated coffee among people who exercise frequently versus people who don't. This answer choice is irrelevant.
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.
b
whether people who █████ █████████████ ██████ ████ ██ █████ ██████ ████ █████ ████ █████ ███ █████ ███████ ██████
Even if, in general, people who drink decaffeinated coffee tend to drink coffee less often than those who drink regular coffee, we know from the stimulus that we're only focused on people who actually drink coffee, whether decaf or regular, at the same frequency: three cups a day. So this answer choice brings in a trend that is irrelevant.
Illusory inconsistency
Illusory inconsistency
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion.
c
whether the degeneration ██ ██████████ ██████ ██ ██████ ██ ███████████ ██ ████████ ███ █████ ██████████
This is very relevant to evaluating the argument. If this is true, then the different rates in arthritis might not be because decaffeinated coffee contains something that causes arthritis, but instead that caffeinated coffee is staving off arthritis. This would weaken the author’s argument. If caffeine doesn’t slow degeneration, the argument remains intact.
Alternate explanation
Alternate explanation
Weaken: Introduce or support an alternate explanation for a phenomenon.
Strengthen: Helps to eliminate an alternate explanation for a phenomenon.
d
whether most coffee ████████ █████ ████ ████ █████ ████ ██ ██████ ███ ███
The study is focused on two groups of people who each drink three cups per day. The hypothesis about the different rates of arthritis between these groups could still be true even if most people actually drink more or less than three cups a day. They would just be running a greater or smaller risk of arthritis accordingly.
e
whether people who ████ █████████ ███ ████ ██████ ████ ███ ███████ ██████████ ██ █████ ██████ ██ ███ ████
Irrelevant. We’re not interested in people who already have arthritis, and how often they drink coffee. We’re interested in the connection between drinking coffee and eventually developing arthritis.