#11 - If the forest continues to disappear at its present

[clairewhited]

I am a little confused about the differentiation between slowing deforestation and stopping. I understand the biologist to be claiming that deforestation couldn't continue at the same rate but the politician to say that the only way to save the koala was to stop deforestation. I selected D because I thought it showed another possibility for saving the koala without "stopping" deforestation (ie. slowing it) which would be inconsistent with the politician's statement but could be consistent with the biologist's (the koala did not approach extinction and the forest did not continue to disappear at the present pace). Is there a different way I should be approaching this question or the wording?

Thank you in advance!

[Robert Carroll]

Claire,

The politician's statement shouldn't be read as claiming that something more extreme is necessary to stop the extinction of koalas. The politician is saying "all that is needed" is to stop deforestation. The contrapositive of the biologist's statement is something like:

koala survives deforestation slowed

The politician isn't saying that more is necessary, but instead erroneously inferring the Mistaken Reversal of what the biologist said:

deforestation slowed koala survives

Now, it's true that the politician switches how extreme the language is, talking about stopping deforestation rather than merely slowing the rate of it. But the point of the politician's statement isn't to say that we need to do more. The politician is saying that all we need to do is stop deforestation - that nothing else is necessary, so that stopping deforestation is sufficient to save the koala.

Robert Carroll

[ogbrandojay]

@steve, isn't the claim that something is needed mean it's necessary, not sufficient. In that case the logic would be
saveK --> (needs) ~Deforestation.

from there we could say that the correct answer choice, AC B, is correct since:
~deforestation --> ~saveK

this is consistent with claims for the bio, but a mess for the politician.

[Jeff Wren]

Hi ogbrandojay,

The politician's statement can be tricky to diagram, and this question gives many people trouble.

The politician states "All that is needed to save the koala is to stop deforestation."

While you're right that the words "is needed" on their own would convey the idea of necessity but here they are being used in the context of the word "all" which conveys the ideas of sufficiency. In this context, the word "all" dominates in terms of the meaning.

For example, if I said "All that is needed to pass this test is to study for 1 hour" that would mean that studying for 1 hour would be sufficient to guarantee that you would pass (according to the original statement).

On the other hand, if I said "If you want to pass this test, you will need to study for at least an hour" the studying would be necessary but not sufficient to guarantee that you will pass.

So here, the diagram for the politician would be:

SD (for Stop Deforestation) -> SK (for Save Koala)

Now the one thing that cannot happen according to this conditional statement is the sufficient occurring without the necessary, which would be that we Stop Deforestation, but we don't Save the Koala. This is exactly what happens in Answer B. Notice that Answer B is not a conditional statement. It is simply stating that the Deforestation stopped and the Koala went extinct. In other words, it's showing the sufficient condition happening without the necessary, which directly contradicts the politician's claim.

[Dancingbambarina]

Hi Dave, I trust you are well.

How do we know Deforestation is not the necessary condition here. I am struggling to piece what is what when the indicators are not presetn. Please may you help me. Thanks so much.

[Dave Killoran]

Eric makes a great explanation of this earlier in this thread:

The phrase "all that is needed" is a tricky one. It includes a sufficient term, "all", as well as a necessary term, "needed." But if you take a step back and think about what that phrase really means, it really equates to "enough" or "sufficient. The other trick is that phrase is modifying "stop deforestation" NOT "save the koala." So here:

"All that is needed to save the koala is to stop deforestation"

is like saying:

"Stopping deforestation is sufficient to save the koala."

So that rule would be diagrammed:

Stop deforestation Save Koala

Thanks!