Try a Sample Logical Reasoning Question: Weaken
Test J, Section 3, Question 21 - Weaken
Ethicist: On average, animals raised on grain must be fed sixteen pounds of grain to produce one pound of meat. A pound of meat is more nutritious for humans than a pound of grain, but sixteen pounds of grain could feed many more people than could a pound of meat. With grain yields leveling off, large areas of farmland going out of production each year, and the population rapidly expanding, we must accept the fact that consumption of meat will soon be morally unacceptable.
Which one of the following, if true, would most weaken the ethicist’s argument?
Even though it has been established that a vegetarian diet can be healthy, many people prefer to eat meat and are willing to pay for it.
Often, cattle or sheep can be raised to maturity on grass from pastureland that is unsuitable for any other kind of farming.
If a grain diet is supplemented with protein derived from non-animal sources, it can have nutritional value equivalent to that of a diet containing meat.
Although prime farmland near metropolitan areas is being lost rapidly to suburban development, we could reverse this trend by choosing to live in areas that are already urban.
Nutritionists agree that a diet composed solely of grain products is not adequate for human health.
To conclude that something is unethical, the author must present some evidence that it is unethical. But there are no premises that even mention ethics or morality. Sure, these things sound bad—I don’t want to run out of food. But just because the consequences of something sound bad, that doesn’t necessarily make it unethical.
To weaken this argument, we want something that suggests that it’s not unethical to eat meat (even though it may have bad consequences).
A. This doesn’t weaken the argument. Just because people prefer meat, that doesn’t mean it’s not unethical to eat it.
B. The ethicist’s point was that it’s unethical to eat meat because we could instead eat the 16 pounds of grains that the animals would've eaten. But if the animals are eating grain that we can’t eat, then the ethicist’s argument doesn’t hold up. This is a great weakener.
C. This strengthens the argument. It shows that we don’t need to eat meat. If we did need to eat meat for nutritional purposes, that would weaken the argument.
D. There were several other reasons to stop eating meat, not just disappearing farmland. So this doesn’t really weaken the argument. What about the expanding population? Shouldn’t we stop eating meat because of that?
E. I don’t care what nutritionists think. They could be wrong. Or they could be right, but it could still be unethical to eat meat. Meat and grain are not the only categories of food. There’s dairy, nuts, vegetables, and fruit. Maybe grain isn’t enough but grain with those other things is enough.