"Good hunter" and "bad hunter" are standard terms in the study of cats. Good hunters can kill prey that weigh up to h...

carettir January 3, 2020

Why not A?

I diagrammed A as HMFR-some-not GH. In the stimulus, I found GH -> HMFR. However, we went over a rule that said that A -> B = B-some-A when A exists. With this rule in mind, I found that HMFR-some-GH. If some cats with a high muscle to fat ratio are good hunters, then wouldn't it follow that some aren't? Is it only wrong because the exact diagram of "HMFR-some-not GH" cannot be deduced?

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Skylar January 6, 2020

@carettir, thanks for your question.

(A) "all good hunters have a high muscle-to-fat ratio" can be diagrammed as "GH -> HMFR." You are correct that this can also be turned into "HMFR - some - GH" assuming GH exist. However, it is important to remember that some is defined as "at least one, possibly all." The fact that some B's are A's does NOT automatically mean that some B's are also not A's. It could be possible that all B's are A's, but we don't have enough information to say either way. For this reason, we cannot deduce "HMFR - some - not GH," and (A) is incorrect.

Does that make sense? Please let us know if you have any other questions and best of luck with your studies!