Based on the passage, it can be concluded that the author and Broyles-González hold essentially the same attitude toward

dalaal on February 28 at 03:32AM

Missing Premises Drills

Hi, Looking at the following drill P: C -> not D P: C: not D some X, I concluded the second premise to be X some C, while the correct answer was C -> X. I realize that we can reverse the C -> X to be X some C. However, why did we go with that option, how do we know that 'all C is X' and not just 'some'?

4 Replies

Ravi on February 28 at 06:47AM

@Dalaal, what you anticipated should work. Was it not listed at all as an answer choice? Could you point me to where in the video lessons or which example this problem is from? Let me know!

dalaal on February 28 at 06:08PM

Hi @Ravi
This is one of the flashcards from the missing premises drills in the quantifies section

Skylar on March 1 at 07:24PM

@Dalaal, happy to help.

Your understanding is valid and correct.

The point of the Missing Premise Drills is to familiarize students with the concepts at their most basic levels and without confusing language. The correct answer for the missing premise is anything that will logically connect the first premise to the conclusion. Here, the answer was written as "C -> X" with a reverse of "X-some-C" in order to test students' understanding of the rule that S->N can be reversed to N-some-S (assuming S exists) and the rule that C->not D and C->X means that at least some not Ds are Xs (assuming C exists). Your answer of "X-some-C" with a reverse of "C-some-X" is correct as well. Both are valid options for connecting the first premise to the conclusion, which is all we're looking for here.

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

Sabine on April 16 at 09:06AM

i still don't understand this point. can you give another example as to why the missing premise is written this way? Thanks