#20 - Amphibian populations are declining in numbers

[George George]

@lsacgals101

Great Q! While it is true that correlation does not conclusively establish causation, it definitely strengthens it. In other words, your takeaway is that showing that two things occur simultaneously is one way to provide additional support for a claim of causation.

[suburbsinmymindseye]

Hi, in an effort to comprehend the answer A. I was wondering if someone could evaluate some of my assertions below.

Would I be correct in stating that answer A) essentially weakens the conclusion by restricting it to only UV-B.

That actually eliminates the possibility of theoretically harmful "UV-C" or "UV-D" rays that the ozone layer could have potentially also stopped. By restricting the protectiveness of the ozone to basically just UV-B, it basically just reiterates the premise, but also tells us that the effectiveness of the ozone stops at the point -- nothing more.

Is my interpretation correct?

[suburbsinmymindseye]

To extend on my last post,

If I were to modify option A to:
A) Of the various types of radiation blocked by atmospheric ozone, UV-B is one of many types that can damage genes.

Would this strengthen the argument? (And thus now be an incorrect answer)

[Jeremy Press]

Hi suburbs,

It's probably a bit of a stretch to call answer choice A a weaken answer. After all, the pieces are already there in the argument to suggest ozone depletion is the primary cause of declining populations. To say that there aren't additional pieces to make ozone depletion the primary cause doesn't weaken the core that's already in place. Saying there are potential alternative causes (which would be, say, the opposite of answer choice D) would weaken the conclusion. But that's not answer choice A.

A better read of answer choice A is simply that it doesn't impact the conclusion.

Conversely (and maybe seemingly in tension with the above), your rephrasing is probably a slight strengthening of the conclusion because it does actually give us additional reasons to believe that ozone depletion can have a negative effect on amphibians (who, for the reasons stated in the argument, are particularly vulnerable to radiation in general).

I hope this helps!

Jeremy

[cornflakes]

Hi,

Would someone be able to explain why B would strengthen the argument? I can see clearly why A wouldn't, but I'm having trouble seeing how knowing anything about what's going on with the non-amphibian population will strengthen (or weaken) a causal relationship that only regards the amphibian population.

The relationship is as follows: Cause (Depletion of Ozone Layer) --> Effect (decline of amphibian population).

B: "Amphibian populations are declining far more rapidly than are the populations of nonamphibian species whose tissues and eggs have more natural protection from UV-B"

The book states that this answer strengthens by demonstrating no cause --> no effect in nonamphibian populations. How does the idea that ozone depletion does not cause a decline in nonamphibian populations affect the plausibility of ozone depletion causing amphibian populations to decline? Does it trade on the idea of hair, hide and feathers? - Are we supposed to infer that because the ozone depletion did not cause the nonamphibians with those protective layers population decline, it somehow strengthens the idea that it would cause it in species that do not have these protective layers? Or, alternatively, would ozone depletion causing population decline in nonamphibians strengthen the idea that there is an alternate cause (because feather protected and non-feather protected beings are both being impacted by the depletion), thus meaning that the negation of thus possibility strengthens the argument?

Both these logical streams seem like a stretch to me as I had to be creative to develop them. I suppose the test makers may hide behind the veneer that "it can be anything between 1%-100%, but in this case these hypotheticals do truly seem to be .01%, even if that. Curious to hear how others saw this one and if I'm missing something obvious.

[Rachael Wilkenfeld]

Hi Cornflakes,

You can think of this like ruling out a potential weakness in the argument. If the opposite was true, that nonamphibian species that had UV-B protection were declinding at the same rate or faster than the amphibian species, it would attack our causal relationship. We'd have no cause, but we'd still have the same effect of the decline.

Answer choice (B) removes that no cause, still effect possibility. It says that in cases without the cause, we don't have the effect of the rapid decline. That would strengthen the causal relationship by showing that it's working as expected. It strengthens it the same way that eliminating an alternate cause would. We are removing potential objections to the argument.

While it's true that it doesn't prove the argument, it does still strengthen. Eliminating potential attacks are a completely valid way to strengthen an argument. We aren't trying to justify it here, just help. Causal arguments are inherently weak, and they need all the help they can get.

Hope that helps!

[teddykim100]

Hi Rachel,

could you explain why answer choice B be a no cause? Isn't the cause ozone depletion? Answer choice B is talking about nonamphibians being exposed to ozone depletion (by highlighting how nonamphibians have protection to UVB), and having no effect as a result.

Could you elaborate on what the "cause" here would be?

[teddykim100]

to elaborate on the above,

The first answer on this thread, by "administrator", also said that answer choice B shows how a "absence of cause, shows that effect does not occur", but if the cause is ozone depletion (taken from the author's conclusion), how does B show an absence of ozone depletion?


Thank you!!

[Robert Carroll]

teddykim,

There's a mediating cause, though. The depletion of the ozone layer doesn't hurt amphibians per se, it hurts them because they lack protection against UV-B. So there's really a combination of causes - depleted ozone PLUS UV-B MINUS protection leads to declining population. Depletion in ozone wouldn't lead to population declines in organisms that have protection against UV, or, theoretically, organisms that thrive on UV. Answer choice (B) shows that - remove one of the causes (lack of protection) and the effect (decline in population) also disappears.

Robert Carroll