LSAT 145 | Section 2 | Logical Reasoning: Q3

LR Question 3 Explanation

QUESTION TEXT: The current sharp decline in commercial honeybee…

QUESTION TYPE: Necessary Assumption

CONCLUSION: Inbreeding is probably the real underling cause of the decline in bees populations.

REASONING: There has been more inbreeding, and bees now lack genetic diversity. In the short run, bees face threats from bacteria, viruses, pesticides and mites.

ANALYSIS: This may sound like a good argument already. If so, that’s because you’re making an outside assumption: genetic diversity is good. And this is a fairly valid assumption: we know inbreeding leads to birth defects and other problems.

But….can lack of genetic diversity cause massive population declines? That we don’t know. This is the missing assumption.

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1. This doesn’t say that inbreeding can cause massive population declines. We also don’t know whether wild honeybees have also been declining.
2. This tells us that if inbreeding is a problem, it will be hard to fix. But we’re trying to prove that it’s a problem.
3. This tells us that if lack of genetic diversity is a problem, then it’s getting worse. But we’re trying to prove that lack of genetic diversity is the cause.
4. This weakens the argument, by showing that the mites and viruses could have destroyed even a diverse bee population.
5. CORRECT. Without this, we have no reason to expect that loss of genetic diversity will lead to population declines.
   Negation: Bees without genetic diversity are as resistant to adversity as genetically diverse bees are.
   Note: You might have avoided picking this because it said “adverse conditions” instead of “viruses, bacteria, pesticides and mites”. But those are certainly adverse conditions!
   Term switches aren’t a problem. It’s switches in concepts you have to watch out for.