Logical Reasoning

PT140 · S1 · Q16 At the end of 1997

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At the end of 1997 several nations stated that their oil reserves had not changed since the end of 1996.

Conclusion

Most of the nations claiming their oil reserves are unchanged are wrong (their oil reserves have changed).

Intermediate Conclusion

Oil reserves are unlikely to remain unchanged from one year to the next.

Evidence

Oil reserves drop, when old fields are drained, and rise, when new fields are discovered.

Evaluate

We can use the keywords to interpret the structure. Claim 1. (counterpoint) But Claim 2. (author's arg starting) Therefore Claim 3. (intermed conc) So Claim 4. (main conc)

But here the intermediate conclusion and the main conclusion are pretty similar, so thinking about them will not require two separate thought processes.

If the author thinks is unlikely that any country's oil reserves would stay the same from one year to the next, she must be thinking that most of the time, you have a oil field drained or a new one discovered.

"Oil reserves" are kind of like a country's oil bank account. They can see how much oil they have. Draining oil is like spending money. Discovering a new field is like adding money to the account.

It's theoretically possible that a country drains 100 barrels of oil from an old field and then discovers a new field with 100 barrels of oil in it. That would end up leaving the oil reserves unchanged by the end of the year. So the author is also assuming that it's unlikely that the oil a country drains would cancel out with the oil a country discovers, within a given year.

In terms of the move from Intermediate to Final conclusion, the author is thinking,

This ignores the possibility that the countries saying that X is true are in the minority of all countries but still telling the truth.

After all, we could say , but I wouldn't necessarily conclude that .

Maybe they did get fired twice! "Unlikely" doesn't mean never, so there is some minority of people to whom this might happen.

Similarly, the nations saying that their oil reserves are unchanged might be telling the truth; they might just be the exceptional cases.

Goal

Look for an answer saying , "those effects usually don't cancel out", or .

16.

Which one of the following is an assumption the argument requires?

  1. For any nation with oil

    Unknown Comparison

    The argument was only about the countries who claimed their oil reserves stayed the same. This answer requires ideas about countries who claimed their oil reserves went up or went down. We have no idea whether our author thinks that most of the other countries accurately reported changes to their oil reserves or whether many of those countries were mistaken. (f.e. maybe some countries said their oil reserves went up, when in reality they went down) Since the author never addressed whether other nations are accurate / inaccurate in their oil reserve reporting, we have no way to say she's assuming anything about them, specifically that the probability of being wrong about your reserves is higher than the probability of having unchanged reserves. We could fix this answer by saying, For any nation that claimed its oil reserves were unchanged, it is more likely that the nation was mistaken than that their oil reserves remained unchanged. But this "fixed" version would essentially just be a rephrasing of the conclusion, not an assumption that got our author there.

    20% picked this

  2. Correct

    It is likely that in

    Why this is right

    Our author's conclusion is "they're probably wrong", which translates into "their oil reserves probably changed". How do oil reserves change? Either an old field is drained, a new one is discovered, or both. So the author is assuming that in these nations that are wrong about their supposedly unchanged reserves, either an old field was drained, a new one was discovered, or both.

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

    54% picked this

  3. During the course of 1997,

    Too Specific

    Gradual drops occur when old fields are drained, and sudden rises occur when new fields are discovered. So this answer is essentially saying, "in at least one country, they drained an old field and discovered a new one". Even though that seems like a very plausible speculation, it's not necessary for the author's logic. If we negated this and got, "No nation had both a drain and a discovery in 1997", the author could still make her argument: Sure, none of them had both. But none of them had neither. They all either drained a field or discovered a field, so everybody's reserves changed.

    7% picked this

  4. If a nation incorrectly stated

    If "Conclusion"

    With conditional answers, we want to think about how they look and consider whether they match a "If this is true, then that is true" move that the author made. Did the author go from "we know that they incorrectly stated unchanged" to concluding "thus, they must have had a drain and a discovery"? No. This answer actually has the always-wrong format of "If conclusion". Since the conclusion is "these nations probably incorrectly stated their reserves were unchanged", we would never want an answer that looks like, IF they incorrectly stated their reserves were unchanged ....

    13% picked this

  5. If a nation's oil reserves

    Out of Scope: obligated

    This answer also starts off "If [conclusion], ..." in a disguised way. The author's conclusion is, "The nations saying unchanged are wrong", which means her conclusion is "these nations' oil reserves did change". More easy to spot as a dealbreaker would be the brand new concept of obligated to report the change correctly. This argument is only discussing whether nations are / aren't reporting change correctly (descriptive), not whether nations are obligated / not obligated to do so (normative).

    6% picked this

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