Logical Reasoning

PT137 · S3 · Q23 A species in which mutations

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A species in which mutations frequently occur will develop new evolutionary adaptations in each generation.

Conclusion

A species in which mutations frequently occur will survive dramatic environmental changes.

Evidence

A species in which mutations frequently occur will develop new adaptions every generation. + Only species that develop new adaptions every generation can survive dramatic environmental changes

Evaluation

Because we see conditional logic triggers (will, only if, will) and repeating ideas ("survive dramatic" / "frequent mutations" / "adaptations each generation" are all mentioned twice), we should try to diagram this.

Frequent Mutations → New A's each gen A → B Survive Dramatic → New A's each gen C → B ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ Freq Mutations → Survive Dramatic A → C

Goal

This is making a Necessary vs. Sufficient error with the second premise, thinking that it goes B → C.

How can we make some quick eliminations? We can look for 2 conditional premises and 1 conditional conclusion. We can verify that both conditional premises have the same outcome (right side).

23.

The flawed pattern of reasoning in which one of the following is most closely parallel to that in the argument above?

  1. In a stone wall that

    Bad Premise Match Valid Argument

    The two conditional premises don't have a matching outcome, so we can bail after the 2nd claim. Prop built ? Each S supports other S A ? B Sturdy ? Prop built C ? A This would allow us to infer C ? B, Sturdy ? Each S supports other S, which is exactly what the (valid) conclusion does.

    14% picked this

  2. A play that is performed

    Bad Premise Match Valid Argument

    This is identical to (A). The quickest reason to bail is that the two conditional premises don't end in the same outcome. If we choose to study it further, we'll also see it's another valid argument. performed before a different audience ? Unique reaction A ? B Play ? performed before a different audience C ? A This would allow us to infer C ? B, All plays get a unique reaction, just as the (valid) conclusion does.

    6% picked this

  3. Correct

    A person who is perfectly

    Why this is right

    Perfectly Honest ? Always Tell Truth A ? B Morally Upright ? Always Tell Truth C ? B ??????????????????????????????????????????? Perfectly Honest ? Morally Upright A ? C

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

    65% picked this

  4. An herb garden is productive

    Bad Premise Match Valid Argument

    This is the same as (A) and (B). We could get rid of this as soon as we see that the two premises don't have matching outcomes. Productive ? Well Drained Soil A ? B Well Drained ? Good Soil B ? C We could infer A ? C, which would be Productive ? Good Soil, which is just what this (valid) conclusion says.

    10% picked this

  5. A diet that is healthful

    Bad Premise Match

    This is almost identical to the other three trap answers. We could bail as soon as we saw the two conditional premises didn't have the same outcome. If we choose to keep analyzing, we'd see the conclusion is almost valid. Healthful ? Well balanced A ? B Well balanced ? Fruits & Vegetables B ? C We could infer A ? C, which sounds like Healthful ? Fruits & Vegetables This conclusion is close to doing that, but it has some fuzzy term shifts that keep it from being airtight. Healthful diet vs. healthy, for example.

    4% picked this

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