PT60.S1.Q3 - sulfur dioxide in atmosphere

mitrakhanom1

I translated the following into lawgic:

ES and SPIL --> OS
SPIL---> OS/e
/E and SPIL
Therefore, ES--> OS

I don't understand why in the video explanation the second sentence is dismissed. What does JW mean when he mentions it is not a necessary condition? So he strikes it out along with part of the last sentence and I don't understand why he does that either.
http://7sage.com/lsat_explanations/lsat-60-section-1-question-03/

inactive

Added the link to the video so people can find what you're talking about.

Accounts Playable

I think it helps to breakdown the role of every sentence in the passage. The first sentence is a premise/fact we know to be true. The second sentence is context that adds a bit of tone to the argument: "the increase is troubling." The final sentence is another premise/conditional. Note that we don't have a conclusion, but we could easily make one: the necessary condition is failed (via the first sentence), so the negation of the sufficient condition must be true.

Thus, the second sentence is more context than anything else. If you delete the second sentence, the substance of the argument remains: If regulations followed, then decrease. We have a Not decrease (increase, in fact). Therefore, we can infer that the regulations were not followed (answer choice .

Also, can you clarify what you mean by your last two sentences (something is not a necessary condition and striking out part of the last sentence)? Jon doesn't say that it isn't the necessary condition, but rather that the necessary condition has been failed/not been met. In fact, Jon uses the entirety of the last sentence in order to correctly run the contrapositive of the conditional, which allows us to draw the conclusion stated in answer choice B.

Hope this helps!