Logical Reasoning

PT137 · S3 · Q19 Ecologist: One theory attributes

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Ecologist: One theory attributes the ability of sea butterflies to avoid predation to their appearance, while another attributes this ability to various chemical compounds they produce.

Conclusion

The compounds the sea butterflies make aren't the reason they are able to avoid predation.

Evidence

In a study, they added one compound per pellet to see if predators would eat it. For each of the compounds, the predator still ate the pellet with the added compound.

Evaluation

Given that the predators ate each pellet with the added compound, how could we still say that the compounds really are the reason predators avoid these butterflies?

The loophole seems to be that maybe the compounds have to all be present at the same time. After all, if we just felt hydrogen atoms and just felt oxygen atoms, neither one of them would feel "wet". It's only once you put the 2 hydrogen atoms and the oxygen atom together that you get water and its properties. So maybe we can argue that the compounds only work to fend off predators when they are all consumed together (the recipe that predators hate is not triggered by just one compound at a time).

Goal

We could actually call this the famous flaw, Part vs. Whole, since the author is saying, 'Since each compound does not deter predators, the group of compounds together does not deter predators".

19.

The reasoning in the ecologist's argument is flawed in that the argument

  1. presumes, without providing justification, that

    Irrelevant

    The other theory has nothing to do with our analysis. No one said it has to be only one of these theories, or even that it has to be at least one of these theories (there could be another possible explanation as well). The reasoning is simply, "If each compound individually failed to deter the predators, then we know that the compounds collectively don't deter the predators".

    13% picked this

  2. draws a conclusion about a

    Bad Premise Match

    Is the conclusion about a cause? Yes, in the anti-causal sense. It concludes that compounds are not the cause of butterflies' ability to avoid predation. Is the premise a correlation? Nope. It's a study in which they put one compound at a time onto pellets.

    6% picked this

  3. treats a condition sufficient for

    No Conditional Logic

    This describes the Famous Flaw Necessary vs. Sufficient, which is when the author messes up conditional logic. There was no conditional logic in this, no condition that guaranteed that butterflies could avoid predators. This answer would describe an argument that sounds like, "Any sea butterfly with these compounds will be able to avoid predators. However, the Caspian sea butterflies don't have those compounds. Thus, they cannot avoid predation."

    12% picked this

  4. Correct

    infers, from the claim that

    Why this is right

    Does the conclusion make an inference about whether a set of things has an effect? Yes, it concludes that the set of compounds does not have the effect of deterring predators. Is the evidence saying that no single compound has the effect of deterring predators? Yes, they tried each compound individually on a food pellet and it didn't deter.

    Skill tested: Flaw · how this choice captures the argument's function is the move to repeat next time.

    67% picked this

  5. draws a conclusion that merely

    Not Circular

    This describes Circular Reasoning, which is almost always a wrong answer. The conclusion says that the compounds (collectively) are not helping the butterfly avoid predation. No premise said that.

    1% picked this

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