WTF: LR Explanation makes no sense to me! HELP! Forum

[youknowryan]

Here's the statement I am confused about:

Biologist:
If the forest continues to disappear at its present pace, the koala will approach extinction.

Isn't the sufficient condition: forest disappears and the necessary condition koala extinct?
FD->KE

Kaplan says this:
The biologist makes a statement of necessary cause: “it is necessary to slow deforestation if the koala is not to approach extinction.”

[3|ink]

Here's the statement I am confused about:

Biologist:
If the forest continues to disappear at its present pace, the koala will approach extinction.

Isn't the sufficient condition: forest disappears and the necessary condition koala extinct?
FD->KE

Kaplan says this:
The biologist makes a statement of necessary cause: “it is necessary to slow deforestation if the koala is not to approach extinction.”

They're giving you the contrapositive.

If the forest continues to disappear at its present pace, the koala will approach extinction.
FD->KE
If the Koala does not approach extinction, then it must be the case that deforestation did not maintain its pace (it slowed down).
KE->FD

[fosterp]

I don't buy it. The rate of deforestation only needs to change if koala does not approach extinction. Says nothing about needing it to be slowed.

[Unshake]

I don't buy it. The rate of deforestation only needs to change if koala does not approach extinction. Says nothing about needing it to be slowed.

Haha

Rate of deforestation is increasing ---> Koala does not approach extinction.

Call PETA, they have it backwards.

[3|ink]

I don't buy it. The rate of deforestation only needs to change if koala does not approach extinction. Says nothing about needing it to be slowed.

The LSAC does expect you to make some contextual judgments. I've learned this the hard way.

[tomwatts]

Just to elaborate on the point in the previous post: There definitely are some moments when you have to know things like "water puts out fire" or "poisoning the air is bad" or the like. The LSAT doesn't require specialized knowledge, but the instructions specifically say that you should not make assumptions that are "by commonsense standards" implausible or incompatible with the information you're given. That is, they imagine that you possess at least a modicum of "common sense," whatever that means, which might be the relevant point here.

[Sandro]

But that runs into problems because of the realm of possibilities ..... I hate when LSAC makes you make these jumps because we are always looking for necessary ones and have to judge if LSAC is making that jump implied or not..

[gdane]

youre overanalyzing. Not every formal logic question needs to be diagrammed into its mistaken revesal, negation, contrapostive, etc etc. Just answer the question.

Good luck!

[tomwatts]

But that runs into problems because of the realm of possibilities ..... I hate when LSAC makes you make these jumps because we are always looking for necessary ones and have to judge if LSAC is making that jump implied or not..

Well, if it's any comfort, these are pretty rare.

[Saltqjibo]

edit: nm (was thinking of wrong question)