Logical Reasoning

PT141 · S4 · Q18 So far this summer

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So far this summer there has been no rain in the valley.

Conclusion (probably)

It will probably rain in the valley within the next week.

Evidence (since)

There are usually a few inches of rain each summer.

Only one week of summer is left, and so far there's been no rain.

Evaluate

There isn't any conditional logic here, but there are some repeating ideas:

"rain / summer / last week" are mentioned a couple times, so we could potentially assign them symbols.

The author is predicting rain in the coming week because we normally have rain each summer, we haven't so far, and there's only one week of summer left. This is a Math-y flaw where an author interprets the concept of average or probability too literally.

The conclusion has a "probably" strength, so we can start reading each answer by verifying it has the same type of conclusion.

Goal

Let's look for something like - We usually see X happen by marker Y. - X hasn't happened yet and we're almost at marker Y. - Thus, X will probably happen in the remaining time before we get to marker Y.

Or more conversationally, .

18.

The flawed pattern of reasoning in the argument above is most similar to that in which one of the following arguments?

  1. Aisha has finished proofreading all

    Weak Conclusion/Premise Match

    The original argument played off the idea that there is usually rain by time X, so there will probably be rain in the remaining time leading up to time X. This argument is saying there are sometimes a few errors, so there may be errors we find before we're done. Probably/usually are of a different strength than sometimes/may (the former means it's likely, the latter means it's possible). It's possible this answer would turn out to be the best available, and we would have to forgive that difference, but on a first pass we wouldn't be receptive to it.

    16% picked this

  2. There are generally few errors

    Bad Premise Match

    This is fairly tempting, but to match the original we would want to hear, "There usually are a few errors. We haven't found any so far, so there will probably be some in the remaining pages." In the original argument, there is a mismatch between the usual (there's usually a few inches of rain each summer) and the observed (there hasn't been any rain so far). In this argument, there isn't a mismatch. The usual (there are usually few errors) and the observed (there haven't been errors so far) are aligned.

    4% picked this

  3. Correct

    On average, there are a

    Why this is right

    There is usually a few inches of rain each summer. There are a few errors in every issue, on average. One week left, and no rain so far this summer. Two pages left, and no errors so far. Thus, it will probably rain in the next week. Thus, there will probably be errors in the last two pages.

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

    75% picked this

  4. Aisha has proofread several issues

    Bad Premise Match

    Just like (B), there's no mismatch here between the usual and the observed. The original argument was saying, "Since something we usually see occur hasn't yet occurred, it will probably occur soon". This argument is saying, "We usually don't see errors in this journal. And Aisha hasn't seen errors in this journal".

    4% picked this

  5. There usually are errors in

    Bad Conclusion Match

    The conclusion has to be related to the "usual" thing we see. In the original argument, there usually is rain during the summer, and so the conclusion is predicting there will probably be rain (during the remaining week of summer). Here, there are usually errors in each issue of the journal, so the conclusion should be predicting that there will be an error in the remaining part of the journal. Instead, the conclusion is saying that Aisha probably messed up.

    1% picked this

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