Logical reasoning PrepTest 141 · Section 4 · Question 26

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
GMO crops don't need insecticides. Insecticides have harmed wildlife. Therefore, using GMO crops will help wildlife recover.

Answer Anticipation:
The argument establishes that insecticides have harmed wildlife. However, it hasn't established anything about the effect of GMO crops on wildlife. It's possible that these crops would be just as bad—if not worse—for wildlife as the insecticides are! This answer discusses the harm of one option, but not of the other, so the correct answer in this Strengthen with Necessary Premise question should establish that the GMO crops don't hurt wildlife as much or more as insecticides do.

Answer Explanation:
This answer compares the harm to wildlife by GMO crops to that of insecticides, stating that they do less harm—a necessary assumption for the argument to work. If the GMO crops do as much or more damage as insecticides, then switching to them won't help wildlife populations to recover and the argument falls apart.

Key Takeaway:
When two options are being compared, and one is declared as better in some key way, make sure that there's actually information about that method provided. Often, the LSAT will distract by focusing solely on the negatives of the alternative instead of establishing anything positive (or anything at all) about the preferred option.

Incorrect. The conclusion is about using GMO crops, not avoiding using pesticides. While the two go together, it's also possible to use less insecticide without switching to GMO crops, so this answer isn't necessary for the argument to work.

Incorrect. This answer is too extreme in stating that GMO crops are "never" sprayed with insecticides. While the argument relies on some GMO crops not being sprayed by insecticides, if they are sometimes sprayed, the argument could still work.

Incorrect. The argument is about whether this shift would work if it happens, not if it's feasible to make happen. As such, the economics of it are out of scope.

Incorrect. First, this answer reverses the logic in the argument by starting with the use of GMO crops helping wildlife to recover. Second, it's too extreme in stating that the "only" reason GMO crops would help wildlife recover is because of the decreased use of insecticides—if there are other benefits, as well, the argument still holds.