Q8 - According to the "bottom-up" theory

[hilarykustoff]

I'm so lost. Can someone go through this one step by step? Thanks!

[maryadkins]

We're trying to weaken bottom-up theory.

Bottom-up theory is an argument with a core:

number of edible plants determines how many herbivores the ecosystem can support -->

number of herbivores determines how many predators it can support -->

the number of edible plants primarily determines an ecosystem's characteristics AND reducing # of predators wouldn't make a big impact on the ecosystem

(B) tells us the opposite--the number of predators went down, and it changed the whole ecosystem. This is CORRECT.


(A) tells us about an unsuccessful attempt to influence an ecosystem, but it's unsuccessful because of a lack of plants. That's consistent with the theory.

(C) also presents a situation that's consistent with the theory.

(D) replaces one plant with another, which is fine for the herbivores. This is also consistent with the argument.

(E) great, so the population hasn't changed at all? What does this tell us about anything?

[shirando21]

can we sort this problem like this:

The argument tells us Plants-->(influences) Herbivores-->Predators, not vice versa.

A: Plants-->Herbivores =consistent

B: Predators-->Herbivores-->Plants =opposite

C: Plants-->Herbivores-->Predators=consistent

D: Plants-->Herbivores=consistent

E: Plants Herbivores Hunting, not logically linked and hunting is out of scope.

So, B is what we are looking for.

[alandman]

I see this as a casual argument friends.

The conclusion is the first sentence: the availability of edible plants is what primarily determines an ecosystem's characteristic.

Cause: availability of edible plants

Effect: ecosystem's characteristic

So to weaken a causal argument we would need to do one of 3 things:

1) Show that the cause exists but the effect does not
2) Show that the the effect exists but the cause doesn't
3) Show that there's an alternate cause (including reverse causation)

Answer choice B does number 3 -- it reverses the causal relationship:

Cause: ecosystem's characteristic (increased population of herbivore species)

Effect: Decrease in availability of edible plants

[maryadkins]

Good discussion guys! You're thinking about it correctly, yes.

[cgrosinger]

hi

i would appreciate if someone could explain why exactly (a) is wrong?

i am missing the point what needs to be done in order to recognize the right answer.