Logical Reasoning

PT133 · S2 · Q18 The flagellum, which bacteria

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The flagellum, which bacteria use to swim, requires many parts before it can propel a bacterium at all.

Evidence

The flagellum, which bacteria use to SW → MP swim, requires many parts before it (~MP → ~SW) can propel a bacterium at all.

Conclusion

Therefore, an evolutionary ancestor of ~MP → ~SA bacteria that had only a few of these parts would gain no survival advantage from them.

Evaluate

The argument assumes that if the ~SW → ~SA flagellum would not have been able to help the bacteria swim, the flagellum would not have conferred a survival advantage.

18.

Which one of the following is an assumption on which the argument depends?

  1. Any of bacteria's evolutionary ancestors

    Irrelevant Comparison

    The comparison should be between bacteria with all of the parts of the flagellum and bacteria which do not have all of the parts.

    8% picked this

  2. Correct

    For parts now incorporated into

    Why this is right

    This bridges the gap between SA → SW providing a survival advantage and helping the bacteria swim.

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

    61% picked this

  3. All parts of the flagellum

    Supports a Premise

    This supports the premise in SW → MP the argument.

    17% picked this

  4. No evolutionary ancestor of bacteria

    Out of Scope

    The conclusion is hypothetical, so it does not matter whether such an evolutionary ancestor existed.

    3% picked this

  5. Any of bacteria's evolutionary ancestors

    Negation

    This negates the premise of the F → SW argument, which says that bacteria use the flagellum to swim.

    12% picked this

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