Logical Reasoning

PT125 · S2 · Q21 Most people who become migraine

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Most people who become migraine sufferers as adults were prone to bouts of depression as children.

Conclusion

Children prone to depression are likely to suffer migraines as adults.

Evidence

Most people who suffer migraines as adults were prone to depression as kids.

Evaluation

You can’t reverse Most statements. If we know that Most A’s are B, we can say that , but we cannot say . If we know “Most Senators are male”, we can say but we can’t say .

Goal

We want something that has this same flawed structure of inferring backwards via a Most claim. PREMISE 1: Most things that are A were once B. CONCLUSION: Thus, things that are B will likely turn out to be A.

21.

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

  1. Correct

    Most good-tempered dogs were vaccinated

    Why this is right

    Most GTD’s were vaccinated as puppies. Thus, if you’re vaccinated as puppy, you’ll likely be a GTD.

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

    88% picked this

  2. Most vicious dogs were ill-treated

    Valid / Bad Conclusion Match

    This does not reverse the Most statement. It actually correctly reasons that if someone is A, they’re likely B. Most vicious were ill-treated when young. Thus, if vicious then probably ill-treated when young.

    7% picked this

  3. Most well-behaved dogs have undergone

    Bad Conclusion Match

    The conclusion of the original said, “Thus if you’re B, you’re likely to be A”. The conclusion of this is saying, “Thus, if you’re not-B, then you’re not-A”. Most well behaved had training. Thus, if you didn’t have training, you won’t be well behaved.

    1% picked this

  4. Most of the pets taken

    Bad Conclusion Match

    Out Of Scope: "prone to illness or accident"The conclusion of the original said, “thus if you’re B, you’re likely to be A”. This conclusion is saying, “if you’re B, then you’re C”. Instead of looping back to the idea of “taken to veterinarians”, it introduces a third (albeit related) concept of “prone to illness or accident”.

    1% picked this

  5. Most puppies are taken from

    Valid / Bad Conclusion Match

    The conclusion does not reverse the original claim. Instead of saying, “Thus, if you were taken from your mother at eight weeks, you’re probably a puppy”, it begins by saying “Thus, if you’re a puppy older than eight weeks”. This argument is actually valid. If we say “Most American children know their alphabet by age 5”, then we’d be allowed to infer “If you’re an American child older than 5, then you probably already know your alphabet”.

    3% picked this

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