Logical Reasoning

PT6 · S3 · Q3 Fire ants from Brazil now

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Fire ants from Brazil now infest the southern United States.

Conclusion

Importing predator insects from Brazil would benefit the U.S. environment by stopping the increase of the fire-ant population.

Evidence (since)

Fire ants from Brazil are infesting the southern United States. Unlike in Brazil, U.S. fire ants have nests shared by two queens, leading to more aggressive ants that decimate local insect populations, allowing them unopposed access to resources. This causes their population to skyrocket.

Certain predator insects in Brazil limit the fire-ant population.

Evaluate

This argument has a Plan / Goal vibe, so we could organize our thinking that way:

GOAL: overall benefit the US environment PLAN: import the predator insects of Brazilian fire ants.

With plans we go through several formulaic reactions

Is it feasible? Could we really import the Brazilian predators and would they be able to actually subdue the fire-ants in the U.S.?

Will things cooperate? Will the predator insects actually go after the fire-ants or will they find it easier to find a different prey species?

Could it backfire? Is it possible that these insects might do fine in terms of controlling the fire ants but create some new environmental issue that ends up being a net negative?

Goal

Get rid of the four answers that describe necessary assumptions.

Each of the following is an assumption made in the argument except:

The imported insects would not
Assumed
This has the classic defender "not". The argument stands on the assumption that the Brazilian predator insects won’t cause more damage than the fire ants. If they turned out to be more damaging, that would basically contradict our goal. Negating this gives us the "plan will backfire" objection.
9% picked this
The predator insects from Brazil
Assumed
This is necessary because if the predators can't survive, they obviously can't fulfill their role in controlling the ant population. Negating this gives us the "plan isn't feasible" objection.
5% picked this
The especially aggressive fire ants
Assumed
Again, we see the Defender "not", so we negate and ask if it would weaken if "the fire ants ARE able to destroy the predator insects". Of course, that would mean the Plan failed. This negation gives us a "plan isn't feasible" objection.
10% picked this
Correct
The predator insects would stop
Why this is right
This choice is different from the others as it introduces a specific prediction about geographic spread. Whether or not the ants are stopped before spreading further north isn’t necessary to claim that importing predators would benefit the environment overall. The statement is thus not necessarily required for the argument. If we negate this and say that "the ants would manage to spread farther north before the predators could stop them", it does sound bad, but not hopeless. The predators could still eventually stop the increase. We might just have to bring them to the north also.
Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.
69% picked this
The rate of increase of
Assumed
If the fire ants multiply faster than they are controlled by predators, the plan fails. The predators wouldn't actually be able to subdue the ants, because the ants' population would be ever-growing.
7% picked this

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