Logical Reasoning

PT150 · S3 · Q8 Of the many works in a collection

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Of the many works in a collection from Japan's Tokugawa period that the museum will soon put on display, those that are most sensitive to light, as well as the most valuable pieces, will be on display for two weeks only.

Conclusion (so / clearly)

Hoitsu's Spring and Autumn Maples is among the most valuable pieces in the collection.

Evidence

It will be on display for two weeks only.

The works that are most sensitive to light and the works that are the most valuable pieces will be on display for two weeks only.

Evaluate

Our immediate reaction to this might be, valuable" category rather than the "sensitive to light" category.

But the argument is also making an Illegal Reversal by going from the fact that Hoitsu's work will be on display for 2 weeks only to either of those trigger ideas. It's possible that his work will be on display for 2 weeks only for some other reason we haven't even mentioned yet. The argument never said that these are the only two categories of things that are 2 weeks only displays.

Goal

Since there are multiple flaws, the correct answer will probably exhibit both of them. If we wanted to think about this symbolically, we could say:

Prem 1: A or B → C Prem 2: Thing X is C. Conc: Thing X is B.

That has both the illegal reversal from the outcome, C, to the trigger. And it also has the arbitrary choice of concluding B, when A would be just as valid a choice.

8.

The flawed pattern of reasoning in the argument above most closely parallels that in which one of the following?

  1. The city council will soon

    Bad Premise/Conclusion Match

    This gives us a conditional that could match up with our "A or B → C". If existing structure → on the map or planned development So, looking at our recipe, what would the next ingredient need to sound like? Premise 1: A or B → C Premise 2: Thing X is C. Conclusion: Thing X is B. We'd need to hear, "Thing X is on the map". And then the conclusion would arbitrarily pick one or the other trigger idea. "Thus, Thing X is an existing structure", or "Thus, Thing X is a planned development".

    4% picked this

  2. The city map was recently

    Bad Premise Match

    This fails to give us any conditional that could match up with our "A or B → C". We basically get two separate conditionals. If new map and purple dot → public building If old map and blue dot → public building So, looking at our recipe, what would the next ingredient need to sound like? Prem 1: A or B → C Prem 2: Thing X is C. Conc: Thing X is B. We'd need to hear, "Thing X is a public building", in order for the author to perform an illegal reversal. Instead, the premise is talking about a "blue dot on the new map", which isn't a trigger or outcome we even have.

    8% picked this

  3. I have just purchased the

    Bad Premise Match

    This fails to give us any conditional that could match up with our "A or B → C". We basically get two separate conditionals. If thoroughfare → solid line If dotted line → one-way street Those don't have the same outcome, so we can't match up with the original: if most sensitive to light → 2 weeks only if most valuable → 2 weeks only

    2% picked this

  4. On this city map, a

    Bad Premise Match

    This fails to give us any conditional that could match up with our "A or B → C". We basically get a simple trigger with a compound outcome. If solid line → city limits or major thoroughfare This argument also doesn't have enough premises. It goes straight from these conditionals into the conclusion.

    1% picked this

  5. Correct

    The legend on this city

    Why this is right

    We can match this up with the original argument. Premise 1: A or B → C Historical monument → purple dot or hospital Premise 2: Thing X is C. This thing on Wilson Street is purple dot. Conclusion: Thing X is B. This thing on Wilson Street is a hospital. This replicates both the illegal reversal and the arbitrary choice between two options.

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

    85% picked this

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