Logical Reasoning

PT152 · S1 · Q23 Male boto dolphins often carry objects

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Male boto dolphins often carry objects such as weeds or sticks.

Conclusion

The behavior males exhibit of carrying weeds or sticks is probably a mating display.

Evidence

If it were play, rather than mating, we would expect females and kids to do it too.

But only adult males do it.

Evaluate

This argument has the general feel of a Curious Fact / Explanation type argument. The conclusion arrives at the more probable explanation (it's mating behavior) by ruling out an alternative explanation (it's not play).

What's important, structurally, though, is that the evidence used a conditional statement and then triggered its contrapositive.

Goal

We want a Conclusion that's making a probable-strength claim, "X is probably Y".

We want two premises, one conditional and one factual (triggering the contrapositive of the conditional).

conditional premise If X were Z rather than Y, then W would be true.

factual premise But W isn't true.

23.

The pattern of reasoning in the argument above is most similar to that in which one of the following arguments?

  1. If there is a lot

    Bad Premise/Conclusion Match

    The first premise is a conditional If X, then W. The other premise should be a fact that triggers the contrapositive: W is not the case. The 2nd sentence + Conclusion should have said "But Phyliis won't be late to the meeting. Thus, there probably isn't a lot of traffic today."

    6% picked this

  2. I expect the arborist to

    Bad Premise Match

    In (A), they gave us a conditional, and then the fact was the opposite of the trigger. In (B), they give us a conditional, and then the fact confirms the trigger. What we want is a conditional, and then the fact is the opposite of the outcome. Given the conditional, arborist finds tree is diseased ? tree will be cut down we would want a factual premise saying "but the tree will not be cut down".

    5% picked this

  3. If the weather forecast called

    Bad Premise Match

    In (A), they gave us a conditional, and then the fact was the opposite of the trigger. In (B), they gave us a conditional, and then the fact confirmed the trigger. In (C), they give us a conditional, and then the fact confirms the outcome. What we want is a conditional, and then the fact is the opposite of the outcome. Given the conditional, forecast called for big snow ? Roy cancels trip we would want a factual premise saying "Roy will not cancel his trip".

    18% picked this

  4. Correct

    If construction of that building

    Why this is right

    Given the conditional, construction on schedule ? foundation done we would want a factual premise saying "but the foundation isn't done". That's what we get. Then the conclusion should be the opposite of the trigger, "so the construction isn't on schedule" and that's what saying "construction is behind schedule" means. They preserved the probable strength of the conclusion: "probably behind schedule" = "more likely mating display" They didn't preserve the idea of ruling out an alternative, so some people may have started off not liking this answer because it doesn't replicate all the features of the original. But it turns out they're just replicating the contrapositive argument structure: Premise 1: X ? Y Premise 2: ~Y. Conclusion: ~X.

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

    70% picked this

  5. If Tamika makes a big

    Bad Premise Match

    In (A), they gave us a conditional, and then the fact was the opposite of the trigger. In (B), they gave us a conditional, and then the fact confirmed the trigger. In (C), they gave us a conditional, and then the fact confirmed the outcome. In (E), they give us a conditional, and then the fact confirms the trigger. What we want is a conditional, and then the fact is the opposite of the outcome. Given the conditional, big sale ? celebrate we would want a factual premise saying "She will not celebrate". Instead we get "She probably will make big sale".

    2% picked this

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