Q8 - The caterpillar of the monarch

[mnoha]

I was a bit confused by this question, although I know that the right answer is D (after looking at it) and it makes sense to me. I had a hard time eliminating the other answers as being incorrect. Is there advice I can receive on how to approach these types of weakening questions? How do I eliminate incorrect answer choices.

For example, with this question, I initially chose B, and when I went back I knew that D was right, but couldn't explain why D. was wrong.

Thanks for any help!

[ManhattanPrepLSAT1]

This question rests on a core concept in weakening and strengthening questions. You can apply the methodology to question after question in these question types.

The argument posits a causal explanation after merely ascertaining a correlation between two things. The viceroy butterfly is seldom preyed upon and the viceroy butterfly looks like the monarch butterfly. Therefore, the viceroy butterfly is seldom preyed upon because it looks like the monarch butterfly? Maybe... but it could be for some other reason as well.

When the argument posits a causal explanation and the question asks you to undermine the argument. The correct answer will take one of the following three actions.

1. It will provide a possible alternative cause.
2. It will provide an example of the presumed cause without the presumed effect, thereby undermining the relationship.
3. It will provide an example of the presumed effect without the presumed cause, thereby undermining the relationship.

The correct answer (D) does the first of these actions. It offers an alternative cause to that presumed in the argument for why viceroy butterflies are so seldom preyed upon.

(A) is consistent with the information presented in the stimulus. The argument says that "many predators" have a toxic reaction to animals that feed on milkweed plants. That's certainly consistent with the possibility that some predators do not have a toxic reaction.
(B) is irrelevant. This answer choice is comparing individual butterflies with the species in general. The argument is strictly about the species in general, so what happens at the individual level does not affect the argument.
(C) is consistent with the argument. The argument never claimed that viceroy butterfly had no predators.
(D) is correct because it provides an alternative cause to the one offered in the conclusion of the argument.
(E) is irrelevant. Just because some species rely almost exclusively on toxicity to protect them doesn't address what the viceroy butterfly relies on for protection.


If you're interested. To strengthen an argument that posits a causal relationship in the conclusion, rather than providing one of the three actions above, the correct answer will protect the argument from one of those things occurring. It'll rule them out!

Good luck. Let me know if I need to discuss anything a bit further.

[mnoha]

thanks so much!

[WaltGrace1983]

I initially chose (B) as well but I think I figured out where my reasoning went terribly wrong. None of the answers seemed particular attractive.

Correlation: Monarchs are poisonous; Viceroy looks like the monarch; Viceroy is seldom preyed upon.

Conclusion: Viceroys are seldom preyed upon because they look like Monarchs.

This may or may not be true, but we want to weaken the argument. As noted above, we can do this by:

(1) providing an alternative explanation
(2) by showing the cause without the effect
(3) by showing the effect without the cause.

(A) We don't care about some predators that do NOT have a toxic reaction. The argument never said that ALL predators have a toxic reaction. Even if it did, all (A) would do is weaken the premises.

(B) First of all, we don't care about the butterflies in the species. We know nothing about the rest of the butterfly species. Simply put, we don't know if "most members of the species are similarly toxic." Because that is the case, this cannot strengthen or weaken.

SIDE NOTE: If (B) would have merely said "Being toxic to predators will NOT protect individual butterflies," this would actually strengthen though. This is because it rules out an alternative explanation. It rules out "being toxic" as an explanation for WHY the viceroy is so seldom preyed upon. Thus, it is MORE likely that it is so seldom preyed upon BECAUSE OF its visual resemblance.

(C) This wouldn't strengthen nor weaken. Why? (1) Because it is consistent with the argument (remember, we never said ALL predators have a toxic reaction) and (2) because it still doesn't give an explanation for why. The argument is predominantly focused on WHY this phenomenon happens - not that it does happen.

(E) This is very similar to (E), it weakens an alternative explanation, thus strengthening the argument ever-so-slightly. However, it probably couldn't be a correct answer to a strengthen question because we don't know if the Viceroy is one of the "few butterfly species" that is protected.

(D) is correct because it provides an alternative explanation: toxicity. Maybe the Viceroy itself is toxic and that is WHY the Viceroy is so seldom preyed upon.