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Conditional Reasoning [2015ed. Page 171]

PostPosted: Wed Oct 04, 2017 9:32 pm
by FA22raptero
Hello everyone,

I'm working on conditional reasoning. Overall, I find using my intuition works 80% of the time, but sometimes I'm going to need to use the techniques discuss in Powerscore Logical Reasoning Bible Chapter 6 in order to maximize my score.

So, my question stems from question 2 of chapter 6 on page 171. The question is:

Some types of organisms originated through endosymbiosis... [question content removed for copyright reasons].

So, when I use my intuition, I get answer E. But I am practicing my conditional reasoning, and I am not able to get that answer.

I managed to get the following:

NEOR: Nucleomorph is the remains of an engulfed organism's nucleus
SVG: Single version of the gene
(I use slashed /// in order to designate "not")

/NEOR :arrow: SVG
and the contrapositive
/SVG :arrow: NEOR

Which, in the book is generally correct. However, the book than suggest that because:

Premise 1: /NEOR :arrow: SVG
Premise 2: /SVG
Conclusion: NEOR

And then somehow, to my bafflment, they end up with the following logical sequence:

SVG :arrow: /NEOR

I am NOT understanding how they build this conditional reasoning argument. Additionaly, answer choice E does not have any conditional indicators, making it difficult to decide what is the necessary and sufficient condition. Are there any resources out there that help with doing this? Could I ask anyone for a little help? Thanks a tonne!!!

Re: Conditional Reasoning [2015ed. Page 171]

PostPosted: Thu Oct 05, 2017 11:09 am
by Dave Killoran
Hi FA22,

Thanks for the question! First, for anyone else reading, due to additions of materials in the books each year, in the 2017 edition this question now appears on page 187, not 171 (yes, I added that much in just two years, and even more in the succeeding pages :-D ).

I don't happen to have a copy of the 2015 version around, but if I recall correctly, I believe there was a transcription error that moved the slash over on the last diagram you mention. That was immediately corrected, and the diagram that appears there now is: 1 :arrow: R. That might resolve you question there; just let me know!

For further discussions of conditional reasoning, including an analysis of intuition vs technical knowledge, I'm going to refer you to a variety of resources here that you may find helpful:



This is just a small selection of the items we've published on this topic, so I encourage you to go beyond these and explore even more. I frequently write about conditional reasoning since it's so prevalent on the LSAT, so if you search my posts you can find me talking about it quite a bit.

Please let me know if that helps. Thanks!

Re: Conditional Reasoning [2015ed. Page 171]

PostPosted: Thu Oct 05, 2017 1:24 pm
by FA22raptero
Hello Dave,

Thanks a lot for the reply! Pretty cool talking to the author...

I purchased the book a couple years ago and then didn't decide to study it until now; too bad as it sounds like there is some great new material in it. Even though I don't have the newest edition, this is a great book, and I especially love the structure when you talk about individual questions. However, I have a completely unsolicited comments about it that I think might improve it, if you care at all: While reading the book front to back, the different chapters on methods of argumentation simply felt peppered throughout the book, with little comment about why the chapters where they were. Even a short page or two explaining to the reader that there are a few principled ways of arguing that the authors use when writing the question would probably have made it so that I didn't have to go back an re-read these sections (i.e., premise and conclusion, conditioinal reasoning, cause and effect reasoning, formal logic reasoning etc.). When I did the conditional, cause and effect and the formal logic sections, I really had no idea why I was learning them, or when I would need to use these tools. I believe a short little page or two in the introduction outlining that you are going to teach these different argumentation styles throughout, and what they mean, could have helped the reader 'prephrase' the various topics that are being taught in order to get a better grasp of the structure of the book. For what that's worth! ;)


This completely resolved my question by the way. I was quite confused and for the life of me could not figure out the answer. However, I've worked on my conditional reasoning and managed to do all the practice questions fine; albeit slowly. I imagine this sort of thing will take a lot of practice to fully understand.

I'm almost done my little cheat sheet for logical reasoning (which I will use when analyzing my incorrect responses), and then I'll move on to your logic bible and reading comprehension books before going into full fling LSAT practice exams mode.

Thanks!!!

Re: Conditional Reasoning [2015ed. Page 171]

PostPosted: Thu Oct 05, 2017 6:14 pm
by Dave Killoran
Hi FA22,

Thanks for the reply! That's a cool idea, I'll look to try to include some more "preview and foreshadowing" comments early in the book that will hopefully make things make more sense. I've tried to do a bit of that over the years, but more certainly can't hurt.

Thanks very much for the suggestion and I'm glad this worked itself out for you!