Logical Reasoning

PT148 · S4 · Q1 Community organizer: Before last year's

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Community organizer: Before last year's community cleanup, only 77 of the local residents signed up to participate, but then well over 100 actually participated.

Conclusion

We can be confident that this year's cleanup will be a success.

Evidence

Before last year's community cleanup, only 77 of the local residents signed up to participate.

Well over 100 actually participated.

This year, 85 residents have signed up to participate.

Our community cleanup will be a success if we have at least 100 participants.

Evaluate

This argument makes a very "confident" prediction about this year's cleanup: it will be a success. That seems to be based on the conditional "if 100+ → success." But do we have enough information to actually trigger that conditional? No way. We only have 85 people signed up. Just because more people showed up than signed up last year doesn't mean that will happen again this year.

Goal

A correct answer might describe this as a type of sampling error: basing a prediction on too small of a sample. It also might point out what we sometimes call a "predictive flaw": predicting the future based on what happened in the past or what's happening in the present. Beware of answers that sound relevant but describe things that don't actually happen in the argument. Also beware of answers that describe other famous flaws which do not occur in this argument.

1.

The reasoning in the community organizer's argument is most vulnerable to criticism on the grounds that the argument

  1. Correct

    generalizes about the outcome of

    Why this is right

    This is definitely an example of a simple flaw run through the dreaded complicator. Did the argument "generalize about the outcome of an event"? Well, the argument claims that this year's cleanup will be a success, which is a decent enough match to keep reading. Is the conclusion "based on a single observation of a similar situation"? Definitely: last year's cleanup. Going back to that first iffier part, I think we can say that the argument generalizes because it assumes that the situation last year is representative. In other words, it treats that instance as though that's what generally happens.

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

    91% picked this

  2. takes for granted that people

    Irrelevant Comparison

    "Takes for granted" means this answer should describe something that the argument assumes. The argument does assume a similarity between last year and this year: that more folks will show up than signed up. But it doesn't assume that the same individuals who showed up last year will show up this year.

    4% picked this

  3. confuses a condition that is

    Necessary vs. Sufficient

    This is describing a conditional logic flaw that does not appear in this argument. The argument does describe a condition that is sufficient (at least 100 participants) for an outcome (the cleanup being a success). But it doesn't take a condition that is required and confuse it with this sufficient condition. For this answer to be correct, the argument would look something like this: If we have at least 100 participants, the community cleanup is going to succeed. We had a successful cleanup, therefore we must have had at least 100 participants.

    4% picked this

  4. overlooks the possibility that the

    Bad Objection

    "Overlooks the possibility" means the answer choice should describe a potential objection, something that will weaken the argument. But the rest of this answer does not describe an objection. If the cleanup attracts participants from outside the community, that could be a good thing for the argument! It might help us reach the 100 participants that we need.

    0% picked this

  5. defines a term in such

    Bad Description

    Sometimes a Flaw answer is wrong because it just doesn't describe what happened in the argument. This argument doesn't define any terms, and what would it even mean to define a term so it always puts a positive spin on the situation? Don't be tempted by the opaqueness of this answer! This is a trap for people who overlooked correct answer A on their first pass. They're hoping you'll think "this answer sounds really technical and hard to understand, therefore this answer is smarter than me, therefore this answer is correct." Don't be fooled!

    0% picked this

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