On some hot days the

Answer choices

1. A

   Not Necessary vs. Sufficient25% picked this

   mistakes a condition that sometimes accompanies unsafe levels of smog for a condition that necessarily accompanies

   This sounds like the #1 famous flaw Necessary vs. Sufficient, in which the author presents a conditional rule in the evidence, and then illegally uses that rule (by reversing it or negating it) in tandem with some other fact to derive the conclusion. There were no conditional claims anywhere in this argument, so there's no chance the author was thinking about anything that "necessarily accompanies unsafe levels of smog". We were told that the condition of "hot days" sometimes accompanies unsafe levels of smog. For the rest of this answer to be true, the argument would have had to argue, "On Day X, there was unsafe smog. Thus, on Day X it must have been hot" or argue "On Day X, it wasn't hot. So therefore on Day X there wasn't unsafe smog."

   25%
2. B

   Correct55% picked this

   fails to recognize that one set might have some members in common with each of two others even though those two other sets have

   Why this is right

   This is a historically funny-hard answer. It's normal to think, "Wha?" on a first pass, but it's 170 behavior to defer on a confusing answer rather than eliminating it just because we don't understand it. Given that our complaint with the argument was something like, "Heyyyy --- you can't prove an overlap between east wind and unsafe smog!", it should somewhat please us to see that this answer is talking about whether or not two sets overlap. What it's saying is that we can have one set, which is the set of "Hot Days in Hillview": {July 15, 19, 22, 30, Aug 1, 3, 9, 14, 20, 25} It has some member in common with two other sets. Here's the set of "Eastern wind days in Hillview": {July 19, 20, 21, Aug 3, 4, 20, 21} Here's the set of "Unsafe Smog days in Hillview": {July 4, 15, Aug 9, 10} We can see that some hot days had unsafe smog: July 15 and Aug 9 Some hot days had wind from the east: July 19, Aug 3, and Aug 20 But there are no dates in common between the set of "unsafe smog" days and the set of "eastern wind" days. In other words, they don't have to overlap.

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

   55%
3. C

   Not Equivocation0% picked this

   uses the key term “unsafe” in one sense in a premise and in another sense

   This describes one of the ten famous flaws, Equivocation, in which the author uses the same term or concept twice but to mean two very different things. That didn't happen here. "Unsafe" meant the same thing every time it was used. Equivocation is almost never the correct answer.

   0%
4. D

   Not Circular1% picked this

   contains a premise that is implausible unless the conclusion is presumed

   This describes one of the ten famous flaws, Circular Reasoning, in which the author's evidence restates the conclusion or presumes the truth of the conclusion. The conclusion was that on some days with eastern wind there is unsafe smog. There definitely was no premise that repeated that. Did either of the two premises presume that? In order to say, "on some hot days the smog is unsafe", do you need to assume that "some days with eastern wind have unsafe smog"? Of course not. Nor do you need to presume the conclusion in order to say the other premise. Answers that describe Circular Reasoning are almost always wrong: - conclusion restates the premise - assumes what it sets out to prove - presumes the truth of the conclusion - presupposes what it seeks to establish

   1%
5. E

   Not Causal19% picked this

   infers a particular causal relation from a correlation that could be explained in a variety

   This describes one of the ten famous flaws, Causal Overconfidence, in which the author overconfidently concludes one potential causal explanation for a curious fact when other possible explanations still exist. Any Flaw answer phrased like infers X from Y means that X should match the conclusion and Y should match the evidence. Is the conclusion talking about "a particular causal relation"? No. There's no causal verb in the conclusion. I can say, "On some days when I go to church, I want NFL football." That does not imply that going to church caused me to watch football.

   19%