Scientists analyzing air bubbles that had been trapped in Antarctic ice during the Earth's last ice age found that th...

Naz December 4, 2014

Answer choice (C) is irrelevant. As mentioned in the explanation in the other thread posted to this question, the scientists' hypothesis is: "the ferrous material which was contained in atmospheric dust, had promoted a great increase in the population of Antarctic algae such as diatoms."

There being other minerals, in addition to the ferrous material, doesn't undermine the scientists' hypothesis. We want to undermine the theory that the presence of unusually large amounts of ferrous material caused the growth in diatom population. Just because there are other materials, does not mean that the ferrous material was not the cause.

Make sure to refer to the other explanation to see how we approach weakening a cause and effect argument.

Hope that clears things up! Please let us know if you have any other questions.

wills March 13, 2019

Is showing that there are other materials that could have caused a decrease in carbon dioxide not an alternate cause that could weaken the hypothesis?

Jacob-R March 15, 2019

I assume you are referring to answer C? The problem is that this answer doesn’t suggest that the other minerals that the dust contained had any impact on the low level of carbon dioxide. We can’t insert that possibility if the answer doesn’t say that.

I hope that helps. Let us know if you have further questions.

hochakin September 22, 2020

In the lecture, we learned to weaken the argument by having alternative cause, for example:

smoke => lung cancer
not smoke => lung cancer

so does the reasoning behind answer C being incorrect means:

not smoke => lung cancer is not enough
not smoke but live near nuclear plant => lung cancer is enough?

that means not only we need an alternative cause, but also that alternative cause needs to provide details that would lead to the stated effect for that alternative cause to be valid?