Logical Reasoning

PT127 · S3 · Q1 Anna: Did you know that rainbows

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Anna: Did you know that rainbows always occur opposite the sun, appearing high in the sky when the sun is low, and low in the sky when the sun is high?

Conclusion

Pliny can't be right about claiming that rainbows always occur opposite the sun.

Evidence

Pliny said a lot of crazy stuff (dog-headed people, shoulder-eyes, curing headaches with snails)

Evaluation

Hey, William, a broken clock is still right twice a day. Just because Pliny has said some patently false stuff before, that doesn't mean we get to assume that every time he claims something it's false. You'd be within reason to conclude that , based on that previous rap sheet. But you can't assume that just because someone has lied / been wrong before, that they must be lying / incorrect in this case.

Goal

This is a form of Ad Hominem, attacking the source of the argument rather than the legitimacy of the ideas. When authors invalidate a point of view based on the source, it's almost always because the source has some ulterior motive / vested interest, or, as it is with this question, because the source's previous claims/behavior somehow undermine their present claim/behavior.

1.

William's argument against Anna's claims about rainbows is most vulnerable to criticism because it

  1. inappropriately distorts Anna's conclusion, making

    Bad Conclusion Match / Not Straw Man

    William doesn't distort Anna's conclusion. He doesn't really even take it head-on. He just tries to invalidate Pliny as a source of true beliefs, given that he has previously been a source of false beliefs. This answer choice describes a flaw people call Straw Man. Karen: The minimum wage hasn't risen in the past ten years, while cost of living goes up 2% per year. Thus, we should raise the minimum wage. Patrick: Well, I don't think we should just give free money to everyone. People need to be encouraged to work their way past entry level jobs that pay minimum wages.

    1% picked this

  2. takes for granted that Pliny

    Trap

    Too Strong / Out of Scope: "bad faith" William is assuming that Pliny was incorrect when he reported about unheard-of creatures, but he doesn't need to assume that Pliny was acting in bad faith, i.e. lying about them. Pliny might be a guy that hears bad info, genuinely believes it, and passes it on in good faith. William would still say, "His track record sucks. Let's not believe him when it comes to rainbows."

    1% picked this

  3. Correct

    illicitly infers that, because Pliny

    Why this is right

    When a Flaw answer choice is structured in two parts, representing the Premise to Conclusion/Assumption move, we can just try matching it up. The author infers that, because [premise], [conclusion]. Is the premise that Pliny made some incorrect assertions? Yes, essentially. Is the conclusion that Pliny's assertions about rainbows are also wrong? Yes.

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

    97% picked this

  4. accepts the assertions of an

    Bad Premise Match

    William does not accept the assertions of Pliny as being valid. He is presenting them as obviously-false ideas, so we're not mad at William for failing to get contemporary science to sign off on Pliny's crazy ideas.

    0% picked this

  5. implies that Pliny the Eider's

    Bad Premise Match

    The author isn't saying, "Don't listen to Pliny, he's too old to be valuable." He's saying, "Don't listen to Pliny, he's said too many crazy things to be trusted."

    0% picked this

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