Logical Reasoning

PT140 · S2 · Q8 Mark: The decongestant drug

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Mark: The decongestant drug Zokaz was discontinued by its manufacturer because long-term studies revealed that it increased the risk of heart attack.

Mark's Conclusion (So)

Qualzan probably increases the risk of heart attack.

Mark's Evidence

Zokaz increased the risk of heart attack, and Qualzan is also a decongestant and works by essentially the same physiological mechanism as does Zokaz.

Kathy's Response

Yes, but they're different chemically, so they probably have different side effects.

Evaluate

Kathy acknowledges that Mark's premise is true (they do operate by the same physiological mechanism), calls into question his conclusion (Q probably doesn't have the same side effect of increasing heart attack risk), and bases this on a premise that offers a distinction (Q and Z are putting different chemicals into our bodies).

Goal

Let's look for something like, .

8.

Which one of the following is a technique of reasoning used in Kathy's response to Mark?

  1. using a product's overall record

    Bad Evidence Match

    Using X as evidence that Y means that X should match the evidence and Y should match the conclusion. Did Kathy's evidence refer to "a product's overall record of safety"? Nope. It referred to "the different chemical compositions of the two drugs".

    1% picked this

  2. attempting to discredit an argument

    Bad Evidence Match

    Attempting to do X by doing Y means that Y should match the evidence and X should match the conclusion. Did Kathy's evidence make an argument that is parallel to Mark's argument and demonstrates its flaw? Nope. It referred to "the different chemical compositions of the two drugs". This answer is describing a response that would sound like this: "Mark, that would be like saying chocolate and broccoli have the same effect on your body, since both of them enter the body through the same chewing mechanism."

    3% picked this

  3. arguing against a conclusion by

    Bad Evidence Match

    Arguing X by raising Y means that Y should match the evidence and X should match the conclusion. Did Kathy's evidence raise questions about the validity of a scientific study? Nope. It just said, "these two drugs have different chemical compositions ".

    2% picked this

  4. attempting to undermine an argument

    Bad Evidence Match

    Attempting to do X by doing Y means that Y should match the evidence and X should match the conclusion. Did Kathy's evidence say that Mark's argument contradicted a fundamental principle of medicine? Nope. It just said, "the two drugs are chemically different".

    14% picked this

  5. Correct

    challenging an argument from analogy

    Why this is right

    Doing X by doing Y means that Y should match the evidence and X should match the conclusion. Did Kathy's evidence focus on a dissimilarity between things being compared? Yes. It said that the two drugs being compared were chemically dissimilar. Was Kathy challenging an argument from analogy? Yes. She was challenging Mark's argument. And his argument is based on an analogy. An argument by analogy is saying, "Thing X and Thing Y have trait A in common. Since Thing X has trait B, Thing Y probably has trait B too". "Z and Q are both decongestants and work by essentially the same physiological mechanism. Since Z increases the risk of heart attack, Q probably also increases the risk of heart attack".

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

    80% picked this

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