The author uses the word "immediacy" (line 39) most likely in order to express

DylanCraig on September 17, 2020

I also would love help with this. I am in the same boat and as well as the missing conclusions. Didn't see any examples in the video.

Thanks!

MelodyWilson on September 18, 2020

In addition to the missing premise drills, I also have questions regarding the Argument Completion Drills. How should I go about solving these types of problems?

Ex. P: not x-> not y
P: x-> not Z
C: ?

Brendyn on September 22, 2020

For the first one you have
A -> C
not D -> C
So wouldn't it make sense that A -> D because they both conclude C

For your second question wouldn't the conclusion be Y -> not Z since...
P: not X -> not Y
Reverse: Y -> X
P: X -> not Z
C: Y -> not Z

SOULCAGES71 on September 27, 2020

In the first example, you are taking the original premise A->C followed by the conclusion's contrapositive not D->C. I am confused here. If I look at this similar to a math equation where there is a set 'formula' for solving these statements, why are you choosing the conclusion's contrapositive? How should we solve these statements from a step-wise approach?

Thank you!

Victoria on October 15, 2020

Hi @MelodyWilson and @DylanCraig,

I would suggest looking through the Message Board on the Sufficient & Necessary Video as a variety of walkthroughs have been posted in the past.

However, I'm happy to help run you through the example you've posted above.

The Missing Premise Drills are not explicitly discussed in the video lesson. Rather, they are designed to familiarize you with the patterns of logic discussed in the lesson. LSAT questions are similar to word problems. Here, we've just broken down the problems into their basic components i.e. the logic linking the different variables.

The first step is always to diagram the contrapositives of the available premise(s) and conclusion. You've done this above, so that's great!

What we need to do next is figure out the missing premise that links the first premise to the conclusion. How do we do that? Using transitive chains

We need to get from Not C --> D

Not C --> _ --> D

We know that Not C --> Not A. This means that Not A --> D.

Not C --> Not A --> D

So, you've just made a slight mistake above. Our missing premise is Not A --> D.

The contrapositive of our missing premise is Not D --> A. Notice that this completes our contrapositive chain.

Not D --> _ --> C

We know that A --> C. Therefore, Not D --> A.

Hope this helps! Please let us know if you have any further questions.

Victoria on October 15, 2020

Hi @MelodyWilson and @Brendyn,

@Brendyn, you are absolutely correct. Keep up the great work!

@MelodyWilson, happy to help!

Again, the goal of these questions is to test your familiarity with the logic presented in the video. The Argument Completion Drills require you to build a transitive chain to properly draw the conclusion.

The first step is always to diagram the contrapositives.

P: Not X --> Not Y
CP: Y --> X

P: X --> Not Z
CP: Z --> Not X

Notice that we can make two transitive chains here.

Z --> Not X --> Not Y
Y --> X --> Not Z

Therefore, we can conclude Z --> Not Y and the contrapositive of this which is Y --> Not Z.

Hope this helps! Please let us know if you have any further questions.

Victoria on October 15, 2020

Hi @SOULCAGES71,

Honestly, I'm a bit confused as to your exact question (I am a law student because I'm bad at math haha). So, I'll try to answer it as best I can but please don't hesitate to let me know if you need any further clarification!

These drills are intended to get you familiar with diagramming logic, contrapositives, and transitive chains.

You can create transitive chains if the sufficient condition of one diagram matches the necessary condition of another.

I can see why you might be confused combining the contrapositive with the premise; however, it's important to remember that contrapositives are logically equivalent to their corresponding premise.

For example, saying "all squirrels are mammals" is logically equivalent to saying, "if you are not a mammal, you are not a squirrel."

Therefore, it is okay to combine premises with contrapositives because they are all logical equivalents.

What matters about these drills is that you understand the underlying concepts. When I was studying for the LSAT, I had a really hard time understanding these drills, but found the questions much easier to wrap my head around.

It's rare in actual questions that you'll be hit with a scenario where you need to make a transitive chain that combines a premise and the contrapositive of another premise, but it's something that you should be aware of as a possibility.

I hope this explanation helps clear things up a bit. Please let me know if you have any further questions.

SOULCAGES71 on November 6, 2020

Thank you Victoria!

It certainly helps!