LR Supplement problem set #1

[lorein21]

In this supplement question 11.

I think I set up the s/n wrong here but I don't really know how to set it up the right way if that is the case.

to me the stimulus read:

Biologist: FD (present pace) -->KAE
Not KAE ---> Not FD

Politician: Not KAE ---> Not FD
FD ---> KAE


I got answer D which I saw as

Not FD ---> Not KAE
I see that i chose one that is a mistaken reversal but I dont see why B is right for this question.

Not FD ---> KAE
is it because the KAE is present as the N in the biologist claim and neither seem exact in the politician claim. if so therese questions I guess i should always diagram even though it takes more time?

[Jon Denning]

Hi lorein - thanks for the question. You're diagram for the biologist is correct, although I'm going to phrase it as "Deforestation --> Not Save Koala" (D --> Not SK). But your diagram for the politician is actually reversed. What the politician is saying is If we can stop deforestation then we will save the koala (Not D --> SK). The phrase "all that is needed" introduces a sufficient condition here because it is the equivalent of "enough" ("Stopping deforestation is enough/sufficient/all we need to save the koala"). The problem with that of course is that it's a mistaken negation of the biologist's point, and represents a misunderstanding on the part of the politician.

Where this question really gets interesting is in the question stem. We are asked to find an answer that is both consistent with the biologist, and inconsistent with the politician. Consistency is actually a REALLY broad idea simply meaning anything that doesn't directly contradict the original statement, so to be consistent with the biologist's argument an answer could say literally anything except for a direct contradiction of D --> Not SK. For instance, "deforestation indicates that pandas will die," "pollution is also a serious threat to koala's survival," "the sky is blue," or "I'm wearing brown shoes" are all consistent with the biologist.

What's going to be much narrower is the idea of inconsistency. For an answer to be inconsistent with the politician's statement, it needs to contradict Not D --> SK. So it should say "No deforestation and the koala is NOT saved (goes extinct)." Answer choice B does exactly that and is therefore correct.

So a really good question here that tests your understanding of conditionality (particularly with that weird "all that is needed" phrase), as well as your understanding of the idea of consistent/inconsistent.

Hope that helps!

Jon

[lorein21]

so lets say I wanted to contradict the Biologist claim my answer would be :

D --> Sk (If Deforestation continues and the koalas survive)

or

This would be the negation of the original statements contrapositive
Sk --> D (If Koalas survive then deforestation continues)


can both of those answers exist. that looks odd to me.

and also to be clear consistency applies to anything in the world that is not a direct contradiction to the condition. even if it weakens the condition by adding another necessary?

thanks again

Lorein