Logical Reasoning

PT153 · S2 · Q18 Some killer whales eat fish exclusively

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Some killer whales eat fish exclusively, but others also eat seals.

Hypothesis

Young harbor seals start off with an aversion to all killer whales but then learn to ignore those that do not eat seals.

Evaluate

When we see the word hypothesis in the question stem, we know that we can use a Curious Fact / Explanation mindset to think about the paragraph (hypothesis = causal explanation). We don't know whether we'll see a typical argument format in which the hypothesis is supported by some evidence or whether it'll just be a hypothesis thrown out there without any particular support.

This one is the latter. We can use the hypothesis to figure out what would be the Curious Question that this hypothesis would be answering.

Curious Question How is it that seals distinguish between the harmful killer-whales and the harmless killer-whales?

Hypothesis They start off afraid of all killer whales but then learn to ignore the harmless ones.

We can evaluate hypotheses through two lenses: - is there some other way to explain this? - how plausible is the author's way?

What could be a different storyline for how the seals distinguish between harmful / harmless killer whales? - maybe they're just born with a genetic ability to differentiate it - maybe they start out being unafraid of all killer-whales and then learn to avoid the ones that are harmful

Goal

Since we're doing Strengthen, a correct answer could rule out one of these alternative hypotheses, but it's more likely that the correct answer gives us a way to help the plausibility of the author's hypothesis.

We would want to see baby seals afraid of all killer whales and then once they learn the dialect of the harmless whales, no longer being afraid of them.

A common Strengthen answer form is No Cause / No Effect, which could sound something like .

18.

Which one of the following, if true, provides the strongest support for the biologists' hypothesis?

  1. Killer whales that eat seals

    Out of Scope: other marine mammals

    The fact that the harmful whales also eat other big mammals doesn't tell us anything about how seals acquire their ability to distinguish between harmful / harmless whales.

    1% picked this

  2. Unlike harbor seals, which can

    Out of Scope: most fish

    We really don't care whether other aquatic animals do / don't have good hearing. The seal has good enough hearing to distinguish between the harmful / harmless whales. We already know that from the evidence. We don't need to be reassured that they have good enough hearing. We want new information that helps us judge the means by which they figure out the difference between harmful / harmless dialects.

    2% picked this

  3. Correct

    When mature harbor seals first

    Why this is right

    This is a No Cause, No Effect answer in the sense that the story we're being sold is this: 1st 2nd 3rd seals are seals learn seals start born scared of dialects of ignoring the all k-whales harmful vs harmless ones harmless This answer is emphasizing that "until they learn to distinguish dialects, they are scared by the sound of k-whales". The fact that this is a mature seal makes the answer harder to compute, but it's establishing that a seal's default position to an unknown whale is "I'm afraid". Over time, the seal can be convinced that a given dialect is associated with harmless behavior, but it ain't takin' any chances at first. So "if a seal hasn't learned a harmless k-whale's dialect" (No Cause) "it has not yet learned to ignore it (it is still in the initial state of aversion)" (No Effect)

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

    59% picked this

  4. Young harbor seals show no

    Weakens, slightly

    This makes the author's hypothesis less plausible. If seals are born with innate aversions to this predator (killer whales), then why wouldn't they have innate aversions to other predators?

    10% picked this

  5. If a fish-eating killer whale

    Unclear Impact

    According to this story, "being attacked" is the causal difference-maker that explains the difference between the attacked seal and all the other seals. Does it help the author's hypothesis to say that "being attacked > having a supposedly harmless dialect"? No, not at all. If anything, the fact that an attacked seal starts avoiding all whales with that dialect makes it seem like actions (attacks) speak louder than words (dialect). But more importantly, this answer says nothing regarding whether seals are being born with fear and acquire partial-trust, or whether they're being born with trust and acquire partial-fear.

    28% picked this

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