Summarize Argument: Counter-Position
The anthropologist concludes that taboos against eating certain animals may not have arisen for practical reasons, like the value of animal labor. This challenges some researchers’ view that the taboos must have had a practical basis. His reasoning is that it’s possible the taboos against eating animals arose first, and people only realized afterwards that they could use the animals for labor.
Describe Method of Reasoning
The anthropologist challenges some researchers’ hypothesis by offering an alternative that accounts for the same facts. He doesn’t claim their hypothesis is false, only that it isn’t necessarily true.
A
calls an explanation of a phenomenon into question by pointing out that observations cited as evidence supporting it are also compatible with an alternative explanation of the phenomenon
The phenomenon is taboos against eating animals, and the explanation is the practical value of animals, e.g. for labor. The anthropologist calls it into question by suggesting that the taboos could have arisen first, and then were followed by the practical usage of animals.
B
establishes that an explanation of a phenomenon is false by demonstrating that the evidence that had been cited in support of that explanation was inadequate
The anthropologist doesn’t argue that the explanation is false, only that it could be false.
C
rejects the reasoning used to justify a hypothesis about the origins of a phenomenon, on the grounds that there exists another, more plausible hypothesis about the origins of that phenomenon
The anthropologist doesn’t say that the other hypothesis is more plausible, only that it’s also plausible.
D
argues in support of one explanation of a phenomenon by citing evidence incompatible with a rival explanation
The anthropologist argues that the evidence could support an alternative explanation, not that it’s incompatible with the original explanation. His argument is that two different hypotheses are consistent with the same set of facts.
E
describes a hypothesis about the sequence of events involved in the origins of a phenomenon, and then argues that those events occurred in a different sequence
The anthropologist doesn’t argue that the events did occur in a different sequence, only that they could have occurred in a different sequence. Like (C) and (B), this is overstating the anthropologist’s belief.
Summarize Argument: Phenomenon-Hypothesis
The argument concludes that a metabolic quirk of the brain is likely to be the reason that many different human hormones can raise the concentration of glucose in the blood. To prove this, the argument cites the fact that the brain can only use glucose for energy, while most other cells can produce energy from fats and proteins. Because glucose is the brain’s exclusive energy source, low levels of glucose in the blood can be very dangerous for brain cells, potentially leading to unconsciousness and death.
Identify Conclusion
The conclusion tells us the reason why different human hormones can raise blood glucose on their own: “The reason for this is probably a metabolic quirk of the brain.”
A
Each of many different human hormones can by itself raise blood glucose levels.
This is the phenomenon that our conclusion sets out to explain. The argument does not provide support for this claim; we accept it upfront, which tells us that this is not the conclusion. The hypothesis that this phenomenon is caused by a metabolic quirk is the main conclusion.
B
The reason that many different hormones can each independently raise blood glucose levels is probably a metabolic quirk of the brain.
This is the claim that the rest of the argument works to prove, which makes it the main conclusion. This statement tells us the cause of the phenomenon introduced in the argument; the rest of the argument provides support for this causal reasoning.
C
Although most human cells can produce energy from fats and proteins, brain cells can produce energy only from glucose.
This claim supports the sub-conclusion that a low level of blood glucose is dangerous for the brain. This answer is a premise, not the main conclusion.
D
If blood glucose levels fall too low, then brain cells starve, resulting in loss of consciousness and death.
This is a sub-conclusion that helps support the main conclusion, which is that a metabolic quirk is the reason many different hormones can raise blood glucose levels. This answer tells us why it is so important for the body to be able to maintain healthy blood glucose levels.
E
The reason brain cells starve if deprived of glucose is that they can produce energy only from glucose.
This statement references the sub-conclusion, but adds causal reasoning into the sub-conclusion. This is not the main conclusion that the entire argument works to support.