Logical Reasoning

PT121 · S4 · Q8 This stamp is probably highly valuable

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This stamp is probably highly valuable, since it exhibits a printing error.

Conclusion

This stamp is probably highly valuable.

Evidence

The most important factors in determining value are - it's in good condition - it's rare - it's old

This stamp is in good condition, and it's quite old, and it has a printing error.

Evaluate

The conclusion we need to prove is that "Stamp X" is probably very valuable.

The main criteria for value were established 1. good condition 2. rare 3. old

We were told explicitly that Stamp X is in good condition and quite old, so the only possible wiggle room here is whether or not it's rare.

The closest thing we know to whether it's rare is that it exhibits a printing error.

Goal

Look for something saying, .

The conclusion is properly inferred if which one of the following is assumed?

The older a stamp is,
Nothing New
This seems to tell us what we already knew. We knew that one of the most important factors in determining value is age. Did we take that to mean older is more valuable or more recent is more valuable? There's no common sense way to think we mean "more recent is more valuable", because the most recent stamps are the ones you can currently buy at the post office, for 50 cents. So it was already implied by common sense that if "age is one of the most important factors in determining value" that we mean the older it is, the more valuable. Granted, this is Sufficient Assumption, so we should need to establish everything from the ground up, but if we're thinking about what the test writers thought was most missing from the evidence, when it comes to 1. condition 2. age 3. rarity we explicitly covered #1 and #2. We need an answer to address #3.
8% picked this
Correct
Printing errors are always confined
Why this is right
The strength of this "always" guarantees that if printing error, then rare Since every printing error only happens on 3 or 4 individual stamps, they are bound to be rare. Again, this plays off the common sense that WAY MORE than 3 or 4 stamps of any kind are ultimately produced. It's weird for this Sufficient Assumption question to be leaning on so much common sense and thus be squishier in terms of "logical proof" than what is normally the case.
Skill tested: Sufficient Assumption · how this choice captures the argument's function is the move to repeat next time.
72% picked this
Most stamps with printing errors
Out of Scope: owned by collectors
Who this stamp is owned by is completely irrelevant to whether or not it's highly valuable.
2% picked this
Rarity and age are of
No Impact
Given that we still have no idea if this stamp is rare or not, we aren't really helped or hurt by learning that rarity = age, in terms of importance.
10% picked this
Even old and rare stamps
Nothing New
This seems to say something we already knew. The 3 big factors in value were 1. condition 2. age 3. rarity We're probably assuming that when something only has 2 out of 3, it's not very valuable. If I have a very old stamp in sparkling condition, it won't be that valuable if it doesn't have much rarity (if 1,000 other people have the same thing). Similarly, as this answer is saying, if I have something old and rare, it won't be that valuable if it's in crappy condition. This answer provides no additional information about "THIS stamp", the one we're trying to investigate.
8% picked this

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