Philosopher: It has been argued that because particular moral codes differ between cultures, morality must be entirel...

tomgbean on December 4, 2019

variables and signs

I would also like an answer to Josh's question as I have the same problem: "Can I ask a question about the missing premise drills? I always seem to be getting the right variables (x or y or z, etc) in the right place in the missing premise but I never seem to be getting the signs on the variables correct (not C vs. C). Can I get some help on the principles behind arriving at the correct variable and sign for these drills?"

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Ravi on December 4, 2019

@tomgbean, Great question. The fact that you're not getting the signs on the variables correct suggests to me that you're either 1) not doing the contrapositives for each statement or 2) incorrectly doing the contrapositives when you do them.

On these types of questions, it's always good to think about how you can get whatever term the argument is concluding on the necessary side. Then, use the contrapositives of each of the premises to see how you can link them up together to create a big chain. Once the chain has been made, then look to see where the gap is between the chain and the overall conclusion of the argument. Once you see the gap, note which variables are required in order to close the gap and what type of relationship they'd need to have. Then, predict what the correct answer is going to be and look for it in the answer choices.

Incorrectly assigning signs to the variables almost always is a function of not properly doing contrapositives, so I recommend reviewing the lessons on sufficient and necessary. Also, if you have specific quantifier questions that you would like help on, please let us know, and we'll be happy to provide written explanations for all of them.

Does this make sense? Let us know if you have any other questions!