Sufficient & necessary conditions

Its_MyAmbition

I am somewhat struggling with diagramming sufficient and necessary conditions with logical reasoning. Some i can answer and some has me a little confused. Are there any tips that could help me understand this? I’m not on 7 sage core curriculum i am studying with LSATMAX, but i also have powerscore bibles and a book called the LSAT trainer that just came in. If anyone could please help me i would greatly appreciate it.

TexAgAaron

@denzeljones14 As someone who also uses the Trainer (as a supplement for 7sage), highly recommend diving into that book! Explains things very well.

What is your issue with Suff/Necc? You said you are having trouble in LR and answering questions. Are you just having trouble with the concept itself or a particular question type?

In general, a sufficient condition is a condition that triggers a necessary one. For that sufficient condition to exist, the necessary must be true as well. But the necessary does not guarantee that the sufficient exists.

Let's use an example: All birds are blue.
Sufficient: All birds
Necessary: Blue things
Logic Version: Bird-->Blue

I know from this statement that if something it is a bird, it will be blue. But does that mean if something is blue, it is a bird? No. Think about the necessary condition as a large circle (blue things) and the sufficient condition as a smaller circle (all birds) within that large circle. Just because something is blue, does not guarantee that its a bird; there is a chance that it is something else. But if we trigger the sufficient (hey we have a bird here), then we know with out a doubt that in this logical world were in, the bird is blue.

And the opposite is true as well. If something is not blue, then we know for sure that it isn't a bird. All birds are contained within all blue things.

It may help to draw this out. Simply put, a logical relationship like this is just a condition that if the sufficient is triggered, we are guaranteed the necessary (a particular result). I could go in to further detail but I'd rather hear some feed back of where you are struggling. I just wanted to put this here in case I can't get back in a timely fashion here haha.

Hope this helped!

Its_MyAmbition

Thanks! That part i understand but as far as applying it to questions like: which of the following closely parallels the reasoning in the argument or which of the following has a logical structure most like the argument above? How do you apply the N&S condition diagram to that? I use the PR>P>C but get confused if something is being negated. I’m probably confusing you and I apologize but it’s confusing me ??... the part I’m having a problem with is applying it to the actual questions if that makes any sense

TexAgAaron

Ah I see. Okay well I'm not sure on what PR>P>C means but I see where you are going.

Parallel method of reasoning mainly focuses on using the same reasoning as used in the stimulus. This can use heavy logic or very little. This is where training in your foundational logic skills can help you immensely.

What can help is making the argument/logic abstract in your mind (i.e. bringing it into that A-->B kind of world) and seeing if the logical reasoning they use, including the conclusion, match up.

However, not all parallel method of reasoning questions use heavy logic. The stimulus may be a researcher weakening an argument of a peer, for example. Fortunately, most of the logical structures used in this type of question are kept pretty simple since they are so long.

Again, just from personal experience, dive heavily into the LSAT Trainer. Very good book! I'd also recommend 7sage as well! JY goes in depth and really teaches this material exceptionally well!