The author uses the word "immediacy" (line 39) most likely in order to express
kzienoon January 1, 2019
Missing Premise
Hello,
I am having huge issues with the missing premise drills. I understand the example you show in the discussions previously, but I am having an issue applying it to other scenarios. For example, I can get the simple P: P: and C: ones but once theres a third premise added I get confused and somehow end up with the contrapositive of the missing premise instead of the positive. How do you know which one is right?
Thank you.
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To further specify on the flashcard
P: not X-->not Y
P:
C: not X-->not B
I would follow this as
P:not X--> not Y
Y-->X
P:
C:not X-->not B
B-->X
so, not x-->not Y -->not B
so not Y--> not B would be the missing premise with
B--> Y as the contrapositive, but the answer has it the other way around.
This is specifically where I am confused. Thanks.
Ravion January 1, 2019
@kzieno,
Happy to help! It sounds to me like you're either 1) confusing the necessary for sufficient conditions when diagramming or 2) you've actually correctly diagrammed the sufficient and necessary conditions but have simply done so in a way that gives you the contrapositive. Do you have a concrete example from one of the specific questions you're having difficulty with? That would help me better see exactly what you're doing in the context of the problem.
The great thing about contrapositives is that they're logically equivalent to the original sufficient and necessary condition.
Let's say that you've diagrammed a premise as not B - ->not A, and the original premise was A - ->B. All you need to do is flip the signs and the position of not B - ->not A (making it A - ->B), and you have the original sufficient and necessary conditions and a logically equivalent statement.
In statements with three or more premises, it helps to pay close attention to figure out how each of the premises is used to support the overall conclusion of the argument. Sometimes, you'll find that one or more of these premises is a subsidiary conclusion, which is a something that is supported by premises but is also used to support another statement in the argument.
Does this make sense? If you could send over an example of a specific problem that you're having difficulty with, that would be very helpful so that we could through it together. Let us know if you have any more questions!
Ravion January 1, 2019
@kzieno,
Apologies; just after I posted my original response, you uploaded the specific problem you were having a problem with. Let's take a look at it.
Your analysis looks great. In the flash card problem you presented, you're correct: not Y - ->not B would be the missing premise, with B - >Y as the contrapositive. What does the answer say? not Y - ->not B? If the answer says not Y - ->not B, then that's fine, as the LSAT often puts the answer in the contrapositive to test whether or not you know that the original statement and the contrapositive are logically equivalent to one another.
Does that make sense? If there are more details to the problem, please let us know!
