Need explanation on contrapositive please

[Fluffy110]

Hi everyone.

With the Flex exam only a couple weeks away, I'm finding myself confused regarding grouping games and contrapositives. When given If then rules, do you always write in and account for the contrapositive?

The best example would be from PT58 classes game.

If History, then neither linguistics nor statistics... Would that automatically translate to If Linguistics AND Statistics, then not History?

Thanks in advance.

-Darren

[Dave Killoran]

Hey Darren,

Thanks for the question! Can you let us know which materials you have of ours? We can then refer you to the best resource to learn more about this key concept.

In short, we often don't write contrapositives out because they are something you should know by second nature when you go to take the test.

Having a place to refer you to would also be helpful so you can learn the rules of handling compound conditions like the rule you cite since you've run into a problem with the "neither/nor" part:

• Rule: If History, then neither linguistics nor statistics...
  
  Diagram:
  
       L
  H +
       S
  
  Contrapositive:

L
or H
S


You had the first diagram wrong, which lead to a problem with the CP. Please let me know if that helps.

Thanks!

[Fluffy110]

Thanks for the response Dave,

I completed as much of the on-demand program as I could afford and have done about 9 hours (of 10) of tutoring. Just to be upfront: I'm 33 years old and have been working since age 16, having had a career in law enforcement followed by a stint in entrepreneurship which allowed me to only now be able (financially) to finish my degree and pursue the dream of law school. I have neither the means nor the resources to spend the money that most prospective law students do. So, I'm limited to the forum, the practice sets that came with tutoring, and the limited tutoring itself.

Please don't read that as a pity party or anything other than what it is: a statement of fact. I'm doing what I can to learn as much as I can with extremely limited resources... With that said, any information or tips you can offer for the limited money I've spent with PowerScore thus far, I'm more than happy to absorb...

Thanks,

-Darren

[Stephanie Oswalt]

Hi Darren!

Thanks for the post! It looks like you have access to the Online Student Center and the On Demand Course videos, so you already have a lot of great material available for practice! Lesson 2 discusses the contrapositive, so I would suggest starting with that On Demand Lesson (about 46 minutes in). In addition, in your Lesson and Homework supplements for Lesson 2, you have homework available for practice along with links to explanations.

Also, feel free to reach out to your tutor, Jay, for some direction. He's awesome and I'm confident he will be able to help give you some personalized tips !

Thanks!

[Dave Killoran]

Let me add to that this post, which discusses the meaning of neither/nor: https://forum.powerscore.com/lsat/viewtopic.php?t=14968, which is where you ran into issues here.

This won't hurt either: https://www.powerscore.com/lsat/help/multiple.cfm

Although I suspect the neither/nor was the real culprit here

Thanks!

[Fluffy110]

Thank you so much Dave and Stephanie.

I did read the article. Just to clarify, the contrapositive of neither nor only requires one of the conditions instead of both?

In keeping with the example: If H then neither S nor L would translate into if S OR L then not H. In that instance, it could allow for S or L or both to meet the conditions necessary to eliminate H, am I understanding that correctly?

Out of everything taught, Lesson 2 was by far my biggest struggle and one I have yet to really grasp. The sufficient and Necessary conditions as well as contrapositives seem to be the most challenging to wrap my brain around. But the clarification given was incredibly helpful.

On a side note Dave, Stephanie, and Jon: Jay has been an unbelievable help thus far. I genuinely wish I could afford more time with him, but that isn't an option unfortunately. In only 9 hours of tutoring and answering questions outside of our allotted time here and there, he has taken me from a 144 baseline test and struggling, to a 158 on my last practice exam. He really does deserve a commendation for his efforts and effective style of instruction.

-Darren

[Dave Killoran]

Hi Darren,

Thanks for the message! Some thoughts:

I did read the article. Just to clarify, the contrapositive of neither nor only requires one of the conditions instead of both?

In keeping with the example: If H then neither S nor L would translate into if S OR L then not H. In that instance, it could allow for S or L or both to meet the conditions necessary to eliminate H, am I understanding that correctly?

Yes, this is how it works, although I tend not to think about the "contrapositive of neither nor" in those terms. Instead, I first focus on what neither/nor means: not both. Once you know that, you know the necessary condition is "not S and not L." Because the contrapositive negates that, it becomes "S or L," which is really "either S or L." This should make sense because neither is simply a contraction of "not either."

On a side note Dave, Stephanie, and Jon: Jay has been an unbelievable help thus far.

That's so great to hear about Jay! I'll definitely pass that along to him. Thanks for sharing!