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kmy265 August 7, 2020

Missing Premise Drills: Answer Choices

Hi, I apologize if I am posting in the wrong section. There was no message board for the Missing Premise Drills. So far, I have been able to successfully fill in all the missing premises following the rules and strategies. However, my answer choice often does not match up with the "correct answer" on the flashcard. I will have logically filled in the missing premise, but my answer often is the contrapositive of the "correct answer". I am so confused. I am finding the missing piece/connection, but my answer is always the opposite (reversed and negated)! I thought that, by definition, the contrapositive is 100% identical in meaning to its original statement. How is it that I am able to reach the missing premise, but my answer does not match up with the flashcard? For example: The correct missing premise answer on the back of the flashcard is: "A -> not x" However, I would have logically reached the answer "X -> not A". Please help, I am not sure if I am missing something fundamentally! Many thanks.

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kmy265 August 7, 2020

I am also having the same issue with Argument Completion Drills. For about less than half of my answers, I am able to fill in the conclusion, but I arrive at the logical equivalent of the answer rather than the "correct" answer.

In my steps, I first find the contrapositives of all premises and conclusion (for missing premise drills). Then I proceed to find the missing connection between 2 variables. Once I have done so, I find the contrapositive (reverse and negated) of that statement. Is my approach correct?

Many thanks in advance.

shunhe August 7, 2020

Hi @kmy265,

Thanks for the question! Don’t worry about that! Like you mentioned, the contrapositive is 100% identical in meaning to its original statement. So if you’re getting the contrapositive as an answer, you’re getting the correct answer, just in a different form. It’s kind of like

Q: What’s 2+2??Answer one: 4
Answer two: Four
“Model” answer: 4

It’s the same thing, just expressed two different ways, both are correct answers. Similarly, if the flashcard says the correct premise is

A —> ~X

And you got

X —> ~A

It means you did it correctly. Just know that this can happen on the LSAT too. You might get

A —> B

And the answer choice might say

~B —> ~A

And so you should pick that one, because they’re logically equivalent.

Hope this helps! Feel free to ask any other questions that you might have.

tara June 4, 2021

How do I restart my quizzes???- without restarting all of my progress in the section? I messed up on a quiz and I need to reset it for accuracy.