Sufficient and Necessary Conditions

[arogm87]

So I've been working my way through the LSAT Bibles, starting with and focusing on the LG Bible the most; however, I'm still finding myself tripping over the sufficient and necessary conditions. In particular, whenever the Unless Equation comes into play. I start second guessing what I'm diagramming and how I'm diagramming it, and I end up coming up with a Mistake Reversal when looking at a Contrapositive.

I noticed this trend going through the rule and diagramming exercises in the LG Bible Workbook. Help!

[Dave Killoran]

Hi A,

Thanks for the question! One of the nice things about our Forum is that most questions have come up before, and so we've had a chance to address them here and on our blog—that makes it easy for you to get a quick start on figuring all of this out!

On this Forum, I've had discussions with a few students you might find useful:

• Avoid Real World Interpretations and Follow the Language: http://forum.powerscore.com/lsat/viewto ... p=216#p216
  
  One More Look on what Sufficient and Necessary Means (this is key so that when indicators aren't present, we know what we're doing): http://forum.powerscore.com/lsat/viewto ... 6166#p6166

On the PowerScore LSAT Blog, we've had the opportunity to write extensively about conditional reasoning, and all of those posts can be found here: http://blog.powerscore.com/lsat/topic/l ... -reasoning. There's also one specifically on the Unless Equation that you might find useful: Diagramming LSAT Conditional Statements 101: Advantages of The Unless Equation


Let's start with those and see if they help. Let us know what you think, and if those help clear things up a bit. Thanks!

[arogm87]

Hi Dave,

You, sir, are a lifesaver! These should help tremendously. I'm reading through the LSAT Q&As first, then I'll move on to the actual blog entries. I am super appreciative of you looking for those examples for me. I'll give them a read a through and hopefully be in a better space.

I'm taking the December 2016 LSAT, and plan on taking the February 2017 LSAT as well, just to make sure I have the best possible score. (While I've been studying since March of this year, medical reasons impeded my progress so I'm trying to hammer as much out as possible again now.)

Thank you again! The books are such a huge help. And I'm glad there's a forum I can go to for more info.