Logical Reasoning

PT136 · S2 · Q5 Bacteria that benefit human beings

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Bacteria that benefit human beings when they are present in the body are called commensals.

Opposing Evidence

Bacteria that benefit human beings when they are present in the body are called commensals.

Stomach ulcers occur in less than 10 percent of those harboring H. pylori.

H. pylori allegedly strengthens immune response.

Opposing Point

Many scientists now consider H. pylori a commensal.

Evidence

Only about 10 percent of the people who harbor Mycobacter tuberculosis—a bacterium that can cause tuberculosis—get sick from it.

No one would call M. tuberculosis a commensal.

Conclusion

The view that H. pylori is a commensal is misguided.

Evaluate

The argument assumes that if M. tuberculosis is not a commensal, that H. pylori is also not a commensal. However, if H. pylori provides more benefit to human beings when present in the body than M. tuberculosis, then the comparison may not be valid.

5.

Which one of the following, if true, most seriously undermines the argument's reasoning?

  1. Stomach ulcers caused by H.

    Strengthen

    This supports the comparison between M. tuberculosis and H. pylori.

    2% picked this

  2. Cases of tuberculosis usually last

    Too Weak

    While this provides a difference between H. pylori and M. tuberculosis, it does not do so on the key point of providing a benefit.

    2% picked this

  3. Correct

    People who harbor M. tuberculosis

    Why this is right

    This weakens the comparison by distinguishing M. tuberculosis from H. pylori in that M. tuberculosis would not benefit people, while H. pylori is known to strengthen the immune system.

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

    88% picked this

  4. There are more people who

    Too Weak

    While this provides a difference between H. pylori and M. tuberculosis, it does not do so on the key point of providing a benefit.

    4% picked this

  5. There are more people who

    Too Weak

    While this provides a difference between H. pylori and M. tuberculosis, it does not do so on the key point of providing a benefit.

    5% picked this

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