Logical Reasoning

PT140 · S1 · Q9 Records from 1850 to 1900

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Records from 1850 to 1900 show that in a certain region, babies' birth weights each year varied with the success of the previous year's crops: the more successful the crops, the higher the birth weights.

Conclusion

The health of a newborn depends to a large extent on the amount of food available to the mother during pregnancy.

Evidence

From 1850 to 1900, babies' birth weights varied with the success of the previous year's crops: more successful crops were associated with higher birth weights.

Evaluate

Our job on Method questions isn't to evaluate the soundness of the argument, so if you're thinking, , you're correct, but call off your dogs. We're not here to fight the logic, just to describe it.

Hopefully, though, our familiarity with causal arguments provides us with some mental vocabulary for describing the move from evidence to conclusion.

The evidence provides a correlation (X varies with Y ... the more X, the more Y). And the conclusion posits some causal relationship (X depends to a large extent on Y).

Goal

We just want an answer that descriptively matches what we saw. We can anticipate that the answer might sound something like .

9.

The argument proceeds by

  1. Correct

    inferring from a claimed correlation

    Why this is right

    When answers say "inferring from Y that X", the Y would be the Evidence and the thing inferred, X, would be the Conclusion. So, was the Evidence a "claimed correlation between two phenomena"? Yes. The evidence claimed a correlation between birth weight and success of crops. Does the conclusion say that two other phenomena are causally connected? Yes. It says that health of a newborn depends strongly on food available to mother. In a weird way, noticing those language shifts from Evidence to Conclusion (i.e. going from talking about "birth weight" to "health of a newborn", or from "success of crops" to "food available to mom") is helping us to understand in this answer choice why it says two other phenomena. If we can match it up, it's correct. And we can match this up.

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

    51% picked this

  2. inferring from the claim that

    Bad Conclusion Match

    We can match this Premise half of this answer up with the Evidence, since "the more successful the crops, the higher the birth weights" is claiming that two phenomena have fluctuated together. But that would mean, according to this answer choice, that our conclusion said, "Therefore, birth weight is caused solely by the success of crops". Not only did the conclusion actually introduce different concepts, not the same two phenomena from the evidence, it also hedges its wording and says "X depends to a large extent on Y", not "Y is the sole cause of X".

    19% picked this

  3. inferring from records concerning a

    Bad Conclusion Match

    We can latch on to the Premise half of this answer choice; there were records concerning a past correlation between "birth weight" and "crop success". But then, according to this answer choice, the conclusion should have sounded like, "This indicates that birth weight and crop success are still associated with each other". That's not a good match for our actual conclusion, which is making a causal (not correlative) claim, and which is talking about things beyond "birth weight" and "crop success".

    11% picked this

  4. inferring from records concerning two

    Bad Conclusion Match

    The evidence definitely had records concerning two phenomena: birth weight / crop success. Does the conclusion say that there is some thing that is causing both birth weight and crop success? No. So we can eliminate from here. Bizarrely, this answer choice goes on to describe yet another Conclusion. This answer acts like the argument had a Premise -> Intermediate Conclusion -> Main Conclusion structure, which it didn't.

    12% picked this

  5. inferring the existence of one

    Bad Premise Match

    If an answer says that we "infer X from Y", then the thing being inferred, X, is a Conclusion and Y is its Evidence. Did we conclude a causal connection? Yes. We concluded that "newborn's health is causally connected to amount of food available to mom during pregnancy". Did the evidence give us another causal connection? No. It just gave us a correlation. Two things "varied" with each other. This is enough to eliminate this answer, but it also goes on to act like there's yet another conclusion, one that says "Here is why X and Y are causally connected and why A and B are causally connected."

    7% picked this

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