Conditional Reasoning Diagramming Drill #11

[leslie7]

Thanks Jeremy and Kelsey! : )

[mikekane245]

Hi there! I had a quick question on numbers 11 and 12 on the Conditional Reasoning Diagramming Section in Chapter 2 (pg 76).

So I know that the part of the statement after the word "unless" or "until" is the necessary condition. We then negate the other part of the statement to get the sufficient condition.

In question 11 we have "G cannot be cleaned until F is cleaned, unless F is cleaned second."
So the first thing I did was take the subphrase "G cannot be cleaned until F is cleaned".
(F is cleaned = F is our necessary condition.
We negate the remaining part of the sentence so
not(G cannot be cleaned) = G can be cleaned is our sufficient condition

sufficient -> necessary
So we have G -> F

Now let's look at the rest of the sentence: "(G cannot be cleaned until F is cleaned), unless F is cleaned second."
So we know that "F is cleaned second" = F2 is the necessary condition since it follows the term "unless."
But why don't we negate the remaining part of the sentence (which is the diagram we got previously) to get the sufficient condition like the book tells us to in the previous section?

In other words, why is the answer (G -> F) -> F2
instead of
not(G->F) -> F2

[Dave Killoran]

Hi Mike,

There's actually a long discussion of these items in the Chapter 3 section of this forum, and your question is explained here: viewtopic.php?f=1347&t=28532

Side note: this drill is in Chapter 3 in the current book, meaning you either mis-posted it in Ch2, or you have a book that is very old. A quick way to tell is that the current LGB has 746 pages. Here's why the books update each year: https://blog.powerscore.com/lsat/the-20 ... -editions/

I think the above explanation I linked will answer your question, but please let us know if not. Thanks!