Logical Reasoning

PT157 · S3 · Q15 Ants sometimes live in hollow places

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Ants sometimes live in hollow places in the roots of a certain orchid species.

Curious Fact

Why are the ant-hosting orchids of a given species healthier than the orchids that don't host ants?

Provided Explanation

The ants store organic matter in the orchids' roots, which provides the orchids with additional nutrients, which makes them healthier?

Goal

Our task is to get an alternate explanation for why there's this correlation between hosting ants and being a healthier orchid.

Whenever we're seeking an alternate explanation for a correlation, we consider two things: Reverse Causality -- Maybe the orchid's superior health comes first, and that causes ants to shelter there.

Third Factor -- Maybe some factor that is associated with the presence of ants (for example, a water supply) is also causing those orchids to grow better.

It's also possible that we just get an alternate explanation where the ants are the cause of the orchid's health, but not because they're putting extra nutrients in the orchid's roots.

15.

Which one of the following, if true, is an alternative explanation for the better health of orchids that house the ants?

Microscopic organisms that are present
No Impact
Microscopic organisms breaking down the organic matter addresses the mechanism of the provided explanation, not an alternative one. We need a different causal story, not more detail about the existing one.
3% picked this
The nutrients present in the
No Impact
If the ant-deposited nutrients are the same as those in the surrounding soil, this weakens the provided explanation but does not offer an alternative. We need a different reason for the health correlation, not a reason to doubt the current one.
8% picked this
Correct
The ants that live in
Why this is right
This provides a completely different causal explanation. The ants prey on insects that eat orchid roots. If the ants protect the orchids from root-eating insects, orchids with ants would be healthier — not because of extra nutrients, but because their roots are not being eaten. This is a different mechanism connecting ants to orchid health: pest control rather than nutrient supplementation.
Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.
87% picked this
The ants that live in
No Impact
The ants not playing a role in pollination has no causal power. We need an explanation where ants do something beneficial. Saying the ants do not do something provides no alternative explanation for the health correlation.
0% picked this
Most plant species whose roots,
Opposite, if anything
If most insect-harboring plants are more prone to disease, this suggests ants should make orchids less healthy, not more. This deepens the puzzle rather than explaining it, and potentially weakens any explanation involving ants benefiting orchids.
1% picked this

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