LSAT Preptest 44 Section 2 Question 8 Explanation | Logical Reasoning

I didn't write the following blog post. It was already on the blog when I took over the URL. The following blog post may contain mistakes. -Steve

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Here's a Logical Reasoning question from the October 2004 LSAT.

As usual, let's make a short chain of phrases to show how the argument progresses:

Plants have natural pesticides --> People ingest them without harm --> synthetic pesticides can be ingested without harm

The argument's saying that natural pesticides and synthetic ones are similar, basically. Let's do a pre-phrase here. What would weaken the argument? Something that suggests the two kinds of pesticides are not similar and thus that synthetic ones may be dangerous even if natural ones aren't.

We need to find something that doesn't weaken the argument since this is an except question, so we need something that doesn't say the two kinds of pesticides are not similar. We see right away that E fits this well, since it talks about a similarity (their chemical structures), not a difference. Let's go through the other choices quickly:

A) The opposite of what we want because it weakens the argument, saying that people have had time to adapt to natural pesticides, unlike synthetic ones, and thus that the latter may be dangerous even if the former isn't.

B) Wrong for the same reason as A. This choice weakens the argument since it shows a dissimilarity between natural and synthetic pesticides (that the latter are more concentrated and dangerous).

C) Wrong for the exact same reason as B.

D) Wrong, again, because it's the opposite of what we are looking for. If synthetic pesticides target more organisms, that's a point where they're less similar to natural ones, and thus maybe more dangerous. The argument is weakened.

E) Correct.

Remember:

1) Pre-phrase an answer (or even what the right answer might look like, as we did here, rather than an exact quote) to save time and increase accuracy since you won't be plodding through the wrong answers.

2) Watch out for answer choices that are the opposite of what you want. Sounds incredibly obvious, but you'd be surprised how often people can be tripped up by answers like that. Happens to the best of us. Just practice a lot so it won't happen to you on test day!