Daily Drills 1 - Section 1 - Question 4

Supply the missing premise that makes the conclusion follow logically: P: D–most–BP: ?C:B–some–C

XZh April 10, 2023

What?

So I get that D-most-B can be understood as most Ds are B's which the contrapositive (Im assuming that's what it is correct me if Im wrong) would be some Bs are Ds. and then I get why if D then C would lead to some Bs are Cs but wouldnt the contrapositive of that be most Cs are Bs and not some Cs are Bs?

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Emil-Kunkin April 12, 2023

Hi, for reference here, I'm going to change the variable names to dogs, buddies, and cute.

We know that most dogs are buddies from the initial premise. We are trying to prove that there is at least one cute buddy. The easiest way to do this would be to also show that all dogs are cute as well, which would guarantee that there are some cute buddies.

The contrapositive of the new statement, If D then C would be if not C then not D.

While the added premise that all D are C would also prove that most Bs are C, the fact that it shows that some are is enough for it to be right.