Logical Reasoning

PT130 · S3 · Q5 Motor oil serves to lubricate engines

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Motor oil serves to lubricate engines and thus retard engine wear.

Conclusion

Cheaper brands of oil are the best buys

Evidence

(It doesn’t seem like there’s any benefit to buying the more expensive stuff), since in this study of taxis that drove 6000 miles all brands of oil did equally well at their goal of retarding engine wear.

Evaluation

Given that all the brands did equally well at their job, how could we still argue that more expensive brands of oil do give you some extra value?

We might think about other good things motor oil can provide, like

However, it seems like the argument restricted us to caring only about X (retarding engine wear). Could we say that the sample tested is misleading? Maybe there’s an important difference between taxis and regular consumer vehicles. Maybe there’s an important difference to how these oils would perform if we judged them at longer intervals, of 15,000 miles, 30,000 miles, etc.

Goal

Find an answer that would allow you argue that even though all the oils did equally well in this study, there is still a compelling reason to buy a higher priced motor oil.

5.

Which one of the following, if true, most weakens the argument?

  1. Cheaper brands of motor oil

    Opposite

    This strengthens the argument, by saying that potential experts in the field of motor oil agree with the author.

    1% picked this

  2. Tests other than of the

    Too Weak

    The key word also takes any punch out of this one. If the test we did was a reliable way to gauge the quality of motor oil, then it doesn’t matter that there are other reliable ways. Reliable ways will tend to all arrive at the same conclusion.

    8% picked this

  3. The lubricating properties of all

    Applies to Both

    Since this fact applies to all motor oils, it is useless to our goal of highlighting some advantage of using the pricier motor oils.

    4% picked this

  4. The engines of some individual

    Unclear Impact / Too Weak

    This is too weak to be correct, as it applies to “at least one” individual car. But this answer also doesn’t specify whether we’re talking about a cheaper or pricier oil, so it’s impact is doomed to be unclear.

    6% picked this

  5. Correct

    Ability to retard engine wear

    Why this is right

    If there are other important properties of motor oil besides retarding wear, then we can’t judge various brands of oil by looking only at how they retard wear. This opens the door for a line of objection such as, “Sure the cheaper brands are just as good at retarding engine wear. But the more expensive brands are better at doing X, which is also important to the running of an engine.”

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

    81% picked this

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