Question regarding certain knowledge belongs to common sense

[EliceC975]

Hey there,

I have a question regarding whether certain knowledge belongs to common sense and can be used in tests.

On Reading Comprehension Strategy Guide, Page 113, Drill It: Inference, Mini-Passage A: The A4 answer is NO for statement "The Earth's core is bigger than the Moon". It is something cannot be inferred according to the answer since the fact that Earth is larger than Moon is considered non-required astronomical knowledge. However, is it just part of the common sense that people can apply on tests?

Thanks a lot!

[ohthatpatrick]

Is the answer saying that the Earth's CORE is bigger than the Moon?
Or that the Earth's Core is bigger than the Moon's Core?

I think we know from common sense that the Earth is bigger than the Moon, but I don't think people have any real idea which planetary body has the bigger core (surely we suspect Earth, but maybe the Moon is 90% core). And I certainly can't judge whether Earth's CORE is bigger than the Moon itself.


Ultimately, though, the concern about what belongs to the sphere of LSAT common sense kind of obscures the issue.

Correct answers don't go against common sense.
"Must be true" answers never require that you use common sense.
"Most supported / most strengthens / most weakens / most helps to explain" will often necessitate some common sense to interpret them.

So if you're doing a question and you're about to pick an answer that would imply that the Earth is smaller than the Moon ... don't, it's wrong.

If you're doing a question about what can actually be derived from the provided info, and you're thinking to yourself "If I just add the fact that everyone knows the Earth is smaller than the Moon" ... don't, there must be a better answer.

If you're doing a question and you're thinking, "This answer choice would weaken, as long as we can assume that environmental pollution could be a potential cause of cancer", then go nuts! That could definitely be the correct answer.

Using common sense on LSAT usually comes in these handful of forms:
1. To interpret one thing as a potential cause of something else, we almost always need to use our common sense knowledge (this would typically be on Strengthen, Weaken, Evaluate, or Explain/Resolve).

2. To pick the BEST AVAILABLE answer on RC, we sometimes need to just use our common sense understanding of what the author was trying to say. We only resort to this when we can't find clear textual support for any of the answers (and it's usually only required of us for 1 or 2 of the 28 available RC questions)

3. We sometimes use our common sense to go from factual claims, "Putting pennies in the toaster would release toxic fumes throughout your house" to normative claims "Putting pennies in the toaster would be bad" / "You shouldn't put pennies in the toaster".
So here, the common sense is "toxic fumes = something bad / something we don't want"

Hope this helps.