A study of the dietary habits

Answer choices

1. A

   Weak Impact10% picked this

   The argument fails to consider whether the dietary habits of everyone in the two groups were the same

   The author does fail to consider other possible differences in diet. We know they ate the same amount of yogurt, but we don't know how the rest of their diets compare. Learning about the rest of their diets, however, would only matter if we found something different in their diets that helped us find some other way to explain why the cancer / low enzyme group had cancer or low enzyme. It's not a strong objection to say to the author, "Hey, author, the dietary habits of every single person in two groups were not identical." You could have 99% of these people on identical diets, and one person eats 1.5 bananas / day while everyone else is eating 1 banana / day, and that sort of fact would already make it true that "the dietary habits of everyone was not the same in all other respects." That language is so extreme, that it's not a realistic demand we would make of any study that looked at people over a 5 year period.

   10%
2. B

   Out of Scope: recommend1% picked this

   The argument neglects to recommend that people with low levels of the enzyme

   The author is only trying to prove that X causes Y. Successfully proving that X causes Y doesn't require that you also advise people against doing X. Someone can prove that "smoking causes lung cancer" without ever saying "I recommend that people don't smoke", so the lack of a recommendation would never be a flaw in an argument that seeks to prove a causal relationship.

   1%
3. C

   Out of Scope: other cancer-causes7% picked this

   The argument focuses on only one substance that can increase the risk of cancer, when it is well known that

   The author is only trying to prove that X causes Y. Successfully proving that X causes Y doesn't require that you also mention everything else that causes Y. Someone can prove that "smoking causes lung cancer" without ever saying "working in a coal mine also causes lung cancer". When we're making objections, we're saying "you failed to prove your conclusion", not "there are other things you should have also talked about beyond what your conclusion was saying".

   7%
4. D

   Correct81% picked this

   The argument overlooks the possibility that cancer causes low levels of

   Why this is right

   This is your classic Reverse Causality answer. The author presents a correlation: being in the cancer group was correlated with having low levels of the enzyme. Then the author assumes that low enzyme caused the cancer. What if cancer caused the low enzyme? Having a cancer or other illness can certainly affect your physiology in ways that may throw levels of certain body chemicals out of whack. Maybe the cancer came first and the low enzymes came second. The most common way to weaken a causal argument is to point out some other way to explain the evidence.

   Skill tested: Flaw · how this choice captures the argument's function is the move to repeat next time.

   81%
5. E

   Irrelevant2% picked this

   The argument does not specify whether any member of either group lacked

   We don't care whether anyone had zero enzyme. As long as the enzyme is "low enough" that the person can't process galactose, then the author can make the same argument. It doesn't matter whether that "low enough" is a tiny bit of enzyme, a speck, or nothing at all.

   2%