Self-study
“If the forest continues to disappear at its present pace, the koala will approach extinction,” said the biologist.
█████ ███ ████ ██ ██████ ██ ████ ███ █████ ██ ██ ████ █████████████████ ████ ███ ███████████
Conditional Claims & Inconsistency
This stimulus provides two conditional claims and asks us for a single statement that’s consistent with the biologist’s and inconsistent with the politician’s. Here are their claims:
Biologist: If deforestation continues apace, the koala will go extinct.
Politician: If we stop deforestation, the koala will survive.*
The thing about conditional statements is that they’re consistent with almost everything, and they’re inconsistent with just one specific state of affairs. The Politician’s claim, for example, is consistent with every imaginable scenario except the one in which we stopped deforestation but the koala went extinct anyway.
That literally hands us the correct answer – to be inconsistent with the politician’s claim, we need a scenario in which deforestation stopped but the koala went extinct.
*For more on why the politician’s claim translates in this direction and not the other way around (or both ways), see (D).
11.
Which one of the following ██████████ ██ ██████████ ████ ███ █████████████ █████ ███ ███ ████ ███ ██████████████ ██████
a
Deforestation continues and ███ █████ ███████ ████████
Consistent with the biologist: “Deforestation continues” triggers the sufficient condition, which means the koala better go extinct! (And it does.)
Consistent with the politician: in this scenario, the politician can say “alas, if only we had stopped deforestation we could have saved the koala.”
b
Deforestation is stopped ███ ███ █████ ███████ ████████
Consistent with the biologist: Their claim is about what happens if deforestation continues – it’s silent on (and therefore consistent with) whatever happens if deforestation stops.
Inconsistent with the politician: “Hey politician! Didn’t you say we would for sure save the koala if we stopped deforestation? But we literally just stopped deforestation and the koala went extinct anyway, you absolute clown!”
c
Reforestation begins and ███ █████ █████████
There are reasons to dislike (C) based on how it interfaces with the conditional statements, but really you should dismiss it because reforestation is an entirely different concept from deforestation. They aren’t even mutually exclusive – there’s a possible world where we’re deforesting one part of the forest and reforesting another.
d
Deforestation is slowed ███ ███ █████ █████████
(D) is wrong because the phrase “all that is needed” means stopping deforestation is sufficient, not necessary, to save the koala.
That might feel crazy looking at the wording – like doesn’t it literally say it’s needed?!? But English is crazy sometimes. Here are some other examples where “all we need is [blah]” just means [blah] is sufficient, not necessary:
All that's needed to look cool is wearing a fedora.
All that's needed to drive fast is a souped up Honda Civic.
All that's needed to fill up on dinner is some beans and rice.
In all these scenarios, there are other methods of [looking cool / driving fast / being full]. Really what these claims are saying is “You’d be surprised to learn that [a fedora / a Civic / beans n’ rice] suffices to meet your goal!”
e
Deforestation is slowed ███ ███ █████ ██████████ ███████████
Consistent with the biologist: Their claim is about what happens if deforestation continues – it’s silent on (and therefore consistent with) whatever happens if deforestation slows or stops.
Consistent with the politician: Their claim is about what happens if we stop deforestation. If we’ve only slowed deforestation, the politician makes no guarantees.